[PATCH v4 00/10] drm/i915: use ref_tracker library for tracking wakerefs

[PATCH v4 00/10] drm/i915: use ref_tracker library for tracking wakerefs

[Andrzej Hajda]

This is revived patchset improving ref_tracker library and converting
i915 internal tracker to ref_tracker.
The old thread ended without consensus about small kernel allocations,
which are performed under spinlock.
I have tried to solve the problem by splitting the calls, but it results
in complicated API, so I went back to original solution.
If there are better solutions I am glad to discuss them.
Meanwhile I send original patchset with addressed remaining comments.

To: Jani Nikula <jani.nikula@linux.intel.com>
To: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
To: Rodrigo Vivi <rodrigo.vivi@intel.com>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: David Airlie <airlied@gmail.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: linux-kernel@vger.kernel.org
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: netdev@vger.kernel.org
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>

---
Changes in v4:
- split "Separate wakeref tracking" to smaller parts
- fixed typos,
- Link to v1-v3: https://patchwork.freedesktop.org/series/100327/

---
Andrzej Hajda (7):
      lib/ref_tracker: add unlocked leak print helper
      lib/ref_tracker: __ref_tracker_dir_print improve printing
      lib/ref_tracker: add printing to memory buffer
      lib/ref_tracker: remove warnings in case of allocation failure
      drm/i915: Separate wakeref tracking types from rpm
      drm/i915: Correct type of wakeref variable
      drm/i915: replace Intel internal tracker with kernel core ref_tracker

Chris Wilson (3):
      drm/i915: Separate wakeref tracking
      drm/i915: Track leaked gt->wakerefs
      drm/i915/gt: Hold a wakeref for the active VM

 drivers/gpu/drm/i915/Kconfig.debug                 |  19 ++
 drivers/gpu/drm/i915/Makefile                      |   1 +
 drivers/gpu/drm/i915/display/intel_display_power.c |   2 +-
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c     |   7 +-
 .../drm/i915/gem/selftests/i915_gem_coherency.c    |  10 +-
 drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c |  14 +-
 drivers/gpu/drm/i915/gt/intel_breadcrumbs.c        |  13 +-
 drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h  |   3 +-
 drivers/gpu/drm/i915/gt/intel_context.h            |  15 +-
 drivers/gpu/drm/i915/gt/intel_context_types.h      |   2 +
 drivers/gpu/drm/i915/gt/intel_engine_pm.c          |  10 +-
 drivers/gpu/drm/i915/gt/intel_engine_types.h       |   2 +
 .../gpu/drm/i915/gt/intel_execlists_submission.c   |   2 +-
 drivers/gpu/drm/i915/gt/intel_gt_pm.c              |  12 +-
 drivers/gpu/drm/i915/gt/intel_gt_pm.h              |  38 +++-
 drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c      |   4 +-
 drivers/gpu/drm/i915/gt/selftest_engine_cs.c       |  20 +-
 drivers/gpu/drm/i915/gt/selftest_gt_pm.c           |   5 +-
 drivers/gpu/drm/i915/gt/selftest_reset.c           |  10 +-
 drivers/gpu/drm/i915/gt/selftest_rps.c             |  17 +-
 drivers/gpu/drm/i915/gt/selftest_slpc.c            |   5 +-
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c  |  11 +-
 drivers/gpu/drm/i915/i915_driver.c                 |   2 +-
 drivers/gpu/drm/i915/i915_pmu.c                    |  16 +-
 drivers/gpu/drm/i915/intel_runtime_pm.c            | 221 ++-------------------
 drivers/gpu/drm/i915/intel_runtime_pm.h            |  11 +-
 drivers/gpu/drm/i915/intel_wakeref.c               |   7 +-
 drivers/gpu/drm/i915/intel_wakeref.h               | 112 ++++++++++-
 include/linux/ref_tracker.h                        |  31 ++-
 lib/ref_tracker.c                                  | 179 ++++++++++++++---
 30 files changed, 469 insertions(+), 332 deletions(-)
---
base-commit: 1ddc2effff762c6a109af52f3c39534c7115aebe
change-id: 20230224-track_gt-1b3da8bdacd7

Best regards,
-- 
Andrzej Hajda <andrzej.hajda@intel.com>

[PATCH v4 01/10] lib/ref_tracker: add unlocked leak print helper

[Andrzej Hajda]

To have reliable detection of leaks, caller must be able to check under the same
lock both: tracked counter and the leaks. dir.lock is natural candidate for such
lock and unlocked print helper can be called with this lock taken.
As a bonus we can reuse this helper in ref_tracker_dir_exit.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 include/linux/ref_tracker.h |  8 ++++++
 lib/ref_tracker.c           | 66 ++++++++++++++++++++++++++-------------------
 2 files changed, 46 insertions(+), 28 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 9ca353ab712b5e..3e9e9df2a41f5f 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -36,6 +36,9 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
 
 void ref_tracker_dir_exit(struct ref_tracker_dir *dir);
 
+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+			   unsigned int display_limit);
+
 void ref_tracker_dir_print(struct ref_tracker_dir *dir,
 			   unsigned int display_limit);
 
@@ -56,6 +59,11 @@ static inline void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
 {
 }
 
+static inline void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+					   unsigned int display_limit)
+{
+}
+
 static inline void ref_tracker_dir_print(struct ref_tracker_dir *dir,
 					 unsigned int display_limit)
 {
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index dc7b14aa3431e2..5e9f90bbf771b0 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -14,6 +14,38 @@ struct ref_tracker {
 	depot_stack_handle_t	free_stack_handle;
 };
 
+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+			   unsigned int display_limit)
+{
+	struct ref_tracker *tracker;
+	unsigned int i = 0;
+
+	lockdep_assert_held(&dir->lock);
+
+	list_for_each_entry(tracker, &dir->list, head) {
+		if (i < display_limit) {
+			pr_err("leaked reference.\n");
+			if (tracker->alloc_stack_handle)
+				stack_depot_print(tracker->alloc_stack_handle);
+			i++;
+		} else {
+			break;
+		}
+	}
+}
+EXPORT_SYMBOL(__ref_tracker_dir_print);
+
+void ref_tracker_dir_print(struct ref_tracker_dir *dir,
+			   unsigned int display_limit)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&dir->lock, flags);
+	__ref_tracker_dir_print(dir, display_limit);
+	spin_unlock_irqrestore(&dir->lock, flags);
+}
+EXPORT_SYMBOL(ref_tracker_dir_print);
+
 void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
 {
 	struct ref_tracker *tracker, *n;
@@ -27,13 +59,13 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
 		kfree(tracker);
 		dir->quarantine_avail++;
 	}
-	list_for_each_entry_safe(tracker, n, &dir->list, head) {
-		pr_err("leaked reference.\n");
-		if (tracker->alloc_stack_handle)
-			stack_depot_print(tracker->alloc_stack_handle);
+	if (!list_empty(&dir->list)) {
+		__ref_tracker_dir_print(dir, 16);
 		leak = true;
-		list_del(&tracker->head);
-		kfree(tracker);
+		list_for_each_entry_safe(tracker, n, &dir->list, head) {
+			list_del(&tracker->head);
+			kfree(tracker);
+		}
 	}
 	spin_unlock_irqrestore(&dir->lock, flags);
 	WARN_ON_ONCE(leak);
@@ -42,28 +74,6 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
 }
 EXPORT_SYMBOL(ref_tracker_dir_exit);
 
-void ref_tracker_dir_print(struct ref_tracker_dir *dir,
-			   unsigned int display_limit)
-{
-	struct ref_tracker *tracker;
-	unsigned long flags;
-	unsigned int i = 0;
-
-	spin_lock_irqsave(&dir->lock, flags);
-	list_for_each_entry(tracker, &dir->list, head) {
-		if (i < display_limit) {
-			pr_err("leaked reference.\n");
-			if (tracker->alloc_stack_handle)
-				stack_depot_print(tracker->alloc_stack_handle);
-			i++;
-		} else {
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&dir->lock, flags);
-}
-EXPORT_SYMBOL(ref_tracker_dir_print);
-
 int ref_tracker_alloc(struct ref_tracker_dir *dir,
 		      struct ref_tracker **trackerp,
 		      gfp_t gfp)

-- 
2.34.1

[PATCH v4 02/10] lib/ref_tracker: __ref_tracker_dir_print improve printing

[Andrzej Hajda]

To improve readability of ref_tracker printing following changes
have been performed:
- reports are printed per stack_handle - log is more compact,
- added display name for ref_tracker_dir,
- stack trace is printed indented, in the same printk call,
- total number of references is printed every time,
- print info about dropped references.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 include/linux/ref_tracker.h | 15 ++++++--
 lib/ref_tracker.c           | 90 +++++++++++++++++++++++++++++++++++++++------
 2 files changed, 91 insertions(+), 14 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 3e9e9df2a41f5f..a2cf1f6309adb2 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -17,12 +17,19 @@ struct ref_tracker_dir {
 	bool			dead;
 	struct list_head	list; /* List of active trackers */
 	struct list_head	quarantine; /* List of dead trackers */
+	char			name[32];
 #endif
 };
 
 #ifdef CONFIG_REF_TRACKER
-static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
-					unsigned int quarantine_count)
+
+// Temporary allow two and three arguments, until consumers are converted
+#define ref_tracker_dir_init(_d, _q, args...) _ref_tracker_dir_init(_d, _q, ##args, #_d)
+#define _ref_tracker_dir_init(_d, _q, _n, ...) __ref_tracker_dir_init(_d, _q, _n)
+
+static inline void __ref_tracker_dir_init(struct ref_tracker_dir *dir,
+					unsigned int quarantine_count,
+					const char *name)
 {
 	INIT_LIST_HEAD(&dir->list);
 	INIT_LIST_HEAD(&dir->quarantine);
@@ -31,6 +38,7 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
 	dir->dead = false;
 	refcount_set(&dir->untracked, 1);
 	refcount_set(&dir->no_tracker, 1);
+	strlcpy(dir->name, name, sizeof(dir->name));
 	stack_depot_init();
 }
 
@@ -51,7 +59,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
 #else /* CONFIG_REF_TRACKER */
 
 static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
-					unsigned int quarantine_count)
+					unsigned int quarantine_count,
+					...)
 {
 }
 
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 5e9f90bbf771b0..ab1253fde244ea 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -1,11 +1,16 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
+
+#define pr_fmt(fmt) "ref_tracker: " fmt
+
 #include <linux/export.h>
+#include <linux/list_sort.h>
 #include <linux/ref_tracker.h>
 #include <linux/slab.h>
 #include <linux/stacktrace.h>
 #include <linux/stackdepot.h>
 
 #define REF_TRACKER_STACK_ENTRIES 16
+#define STACK_BUF_SIZE 1024
 
 struct ref_tracker {
 	struct list_head	head;   /* anchor into dir->list or dir->quarantine */
@@ -14,24 +19,87 @@ struct ref_tracker {
 	depot_stack_handle_t	free_stack_handle;
 };
 
-void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
-			   unsigned int display_limit)
+struct ref_tracker_dir_stats {
+	int total;
+	int count;
+	struct {
+		depot_stack_handle_t stack_handle;
+		unsigned int count;
+	} stacks[];
+};
+
+static struct ref_tracker_dir_stats *
+ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
 {
+	struct ref_tracker_dir_stats *stats;
 	struct ref_tracker *tracker;
-	unsigned int i = 0;
 
-	lockdep_assert_held(&dir->lock);
+	stats = kmalloc(struct_size(stats, stacks, limit),
+			GFP_NOWAIT | __GFP_NOWARN);
+	if (!stats)
+		return ERR_PTR(-ENOMEM);
+	stats->total = 0;
+	stats->count = 0;
 
 	list_for_each_entry(tracker, &dir->list, head) {
-		if (i < display_limit) {
-			pr_err("leaked reference.\n");
-			if (tracker->alloc_stack_handle)
-				stack_depot_print(tracker->alloc_stack_handle);
-			i++;
-		} else {
-			break;
+		depot_stack_handle_t stack = tracker->alloc_stack_handle;
+		int i;
+
+		++stats->total;
+		for (i = 0; i < stats->count; ++i)
+			if (stats->stacks[i].stack_handle == stack)
+				break;
+		if (i >= limit)
+			continue;
+		if (i >= stats->count) {
+			stats->stacks[i].stack_handle = stack;
+			stats->stacks[i].count = 0;
+			++stats->count;
 		}
+		++stats->stacks[i].count;
+	}
+
+	return stats;
+}
+
+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+			   unsigned int display_limit)
+{
+	struct ref_tracker_dir_stats *stats;
+	unsigned int i = 0, skipped;
+	depot_stack_handle_t stack;
+	char *sbuf;
+
+	lockdep_assert_held(&dir->lock);
+
+	if (list_empty(&dir->list))
+		return;
+
+	stats = ref_tracker_get_stats(dir, display_limit);
+	if (IS_ERR(stats)) {
+		pr_err("%s@%pK: couldn't get stats, error %pe\n",
+		       dir->name, dir, stats);
+		return;
 	}
+
+	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
+
+	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
+		stack = stats->stacks[i].stack_handle;
+		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
+			sbuf[0] = 0;
+		pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
+		       stats->stacks[i].count, stats->total, sbuf);
+		skipped -= stats->stacks[i].count;
+	}
+
+	if (skipped)
+		pr_err("%s@%pK skipped reports about %d/%d users.\n",
+		       dir->name, dir, skipped, stats->total);
+
+	kfree(sbuf);
+
+	kfree(stats);
 }
 EXPORT_SYMBOL(__ref_tracker_dir_print);
 

-- 
2.34.1

[PATCH v4 03/10] lib/ref_tracker: add printing to memory buffer

[Andrzej Hajda]

In case one wants to show stats via debugfs.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 include/linux/ref_tracker.h |  8 +++++++
 lib/ref_tracker.c           | 56 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index a2cf1f6309adb2..2fdbfd2e14797a 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -50,6 +50,8 @@ void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
 void ref_tracker_dir_print(struct ref_tracker_dir *dir,
 			   unsigned int display_limit);
 
+int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size);
+
 int ref_tracker_alloc(struct ref_tracker_dir *dir,
 		      struct ref_tracker **trackerp, gfp_t gfp);
 
@@ -78,6 +80,12 @@ static inline void ref_tracker_dir_print(struct ref_tracker_dir *dir,
 {
 }
 
+static inline int ref_tracker_dir_snprint(struct ref_tracker_dir *dir,
+					  char *buf, size_t size)
+{
+	return 0;
+}
+
 static inline int ref_tracker_alloc(struct ref_tracker_dir *dir,
 				    struct ref_tracker **trackerp,
 				    gfp_t gfp)
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index ab1253fde244ea..2ef4596b6b36f5 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -62,8 +62,27 @@ ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
 	return stats;
 }
 
-void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
-			   unsigned int display_limit)
+struct ostream {
+	char *buf;
+	int size, used;
+};
+
+#define pr_ostream(stream, fmt, args...) \
+({ \
+	struct ostream *_s = (stream); \
+\
+	if (!_s->buf) { \
+		pr_err(fmt, ##args); \
+	} else { \
+		int ret, len = _s->size - _s->used; \
+		ret = snprintf(_s->buf + _s->used, len, pr_fmt(fmt), ##args); \
+		_s->used += min(ret, len); \
+	} \
+})
+
+static void
+__ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
+			     unsigned int display_limit, struct ostream *s)
 {
 	struct ref_tracker_dir_stats *stats;
 	unsigned int i = 0, skipped;
@@ -77,8 +96,8 @@ void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
 
 	stats = ref_tracker_get_stats(dir, display_limit);
 	if (IS_ERR(stats)) {
-		pr_err("%s@%pK: couldn't get stats, error %pe\n",
-		       dir->name, dir, stats);
+		pr_ostream(s, "%s@%pK: couldn't get stats, error %pe\n",
+			   dir->name, dir, stats);
 		return;
 	}
 
@@ -88,19 +107,27 @@ void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
 		stack = stats->stacks[i].stack_handle;
 		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
 			sbuf[0] = 0;
-		pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
-		       stats->stacks[i].count, stats->total, sbuf);
+		pr_ostream(s, "%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
+			   stats->stacks[i].count, stats->total, sbuf);
 		skipped -= stats->stacks[i].count;
 	}
 
 	if (skipped)
-		pr_err("%s@%pK skipped reports about %d/%d users.\n",
-		       dir->name, dir, skipped, stats->total);
+		pr_ostream(s, "%s@%pK skipped reports about %d/%d users.\n",
+			   dir->name, dir, skipped, stats->total);
 
 	kfree(sbuf);
 
 	kfree(stats);
 }
+
+void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
+			   unsigned int display_limit)
+{
+	struct ostream os = {};
+
+	__ref_tracker_dir_pr_ostream(dir, display_limit, &os);
+}
 EXPORT_SYMBOL(__ref_tracker_dir_print);
 
 void ref_tracker_dir_print(struct ref_tracker_dir *dir,
@@ -114,6 +141,19 @@ void ref_tracker_dir_print(struct ref_tracker_dir *dir,
 }
 EXPORT_SYMBOL(ref_tracker_dir_print);
 
+int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)
+{
+	struct ostream os = { .buf = buf, .size = size };
+	unsigned long flags;
+
+	spin_lock_irqsave(&dir->lock, flags);
+	__ref_tracker_dir_pr_ostream(dir, 16, &os);
+	spin_unlock_irqrestore(&dir->lock, flags);
+
+	return os.used;
+}
+EXPORT_SYMBOL(ref_tracker_dir_snprint);
+
 void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
 {
 	struct ref_tracker *tracker, *n;

-- 
2.34.1

[PATCH v4 04/10] lib/ref_tracker: remove warnings in case of allocation failure

[Andrzej Hajda]

Library can handle allocation failures. To avoid allocation warnings
__GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been
replaced with GFP_NOWAIT in case of stack allocation on tracker free
call.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 lib/ref_tracker.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 2ef4596b6b36f5..cae4498fcfd701 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -189,7 +189,7 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
 	unsigned long entries[REF_TRACKER_STACK_ENTRIES];
 	struct ref_tracker *tracker;
 	unsigned int nr_entries;
-	gfp_t gfp_mask = gfp;
+	gfp_t gfp_mask = gfp | __GFP_NOWARN;
 	unsigned long flags;
 
 	WARN_ON_ONCE(dir->dead);
@@ -237,7 +237,8 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
 		return -EEXIST;
 	}
 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
-	stack_handle = stack_depot_save(entries, nr_entries, GFP_ATOMIC);
+	stack_handle = stack_depot_save(entries, nr_entries,
+					GFP_NOWAIT | __GFP_NOWARN);
 
 	spin_lock_irqsave(&dir->lock, flags);
 	if (tracker->dead) {

-- 
2.34.1

[PATCH v4 05/10] drm/i915: Separate wakeref tracking types from rpm

[Andrzej Hajda]

These structs will be used by other subsystems.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/intel_runtime_pm.c      | 14 +++++++-------
 drivers/gpu/drm/i915/intel_runtime_pm.h      | 10 +---------
 drivers/gpu/drm/i915/intel_wakeref.h         |  4 ++--
 drivers/gpu/drm/i915/intel_wakeref_tracker.h | 24 ++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 129746713d072f..1901eedb6704a2 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -164,7 +164,7 @@ static int cmphandle(const void *_a, const void *_b)
 
 static void
 __print_intel_runtime_pm_wakeref(struct drm_printer *p,
-				 const struct intel_runtime_pm_debug *dbg)
+				 const struct intel_wakeref_tracker *dbg)
 {
 	unsigned long i;
 	char *buf;
@@ -202,8 +202,8 @@ __print_intel_runtime_pm_wakeref(struct drm_printer *p,
 }
 
 static noinline void
-__untrack_all_wakerefs(struct intel_runtime_pm_debug *debug,
-		       struct intel_runtime_pm_debug *saved)
+__untrack_all_wakerefs(struct intel_wakeref_tracker *debug,
+		       struct intel_wakeref_tracker *saved)
 {
 	*saved = *debug;
 
@@ -213,7 +213,7 @@ __untrack_all_wakerefs(struct intel_runtime_pm_debug *debug,
 }
 
 static void
-dump_and_free_wakeref_tracking(struct intel_runtime_pm_debug *debug)
+dump_and_free_wakeref_tracking(struct intel_wakeref_tracker *debug)
 {
 	if (debug->count) {
 		struct drm_printer p = drm_debug_printer("i915");
@@ -227,7 +227,7 @@ dump_and_free_wakeref_tracking(struct intel_runtime_pm_debug *debug)
 static noinline void
 __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 {
-	struct intel_runtime_pm_debug dbg = {};
+	struct intel_wakeref_tracker dbg = {};
 	unsigned long flags;
 
 	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
@@ -244,7 +244,7 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 static noinline void
 untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
 {
-	struct intel_runtime_pm_debug dbg = {};
+	struct intel_wakeref_tracker dbg = {};
 	unsigned long flags;
 
 	spin_lock_irqsave(&rpm->debug.lock, flags);
@@ -257,7 +257,7 @@ untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
 void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
 				    struct drm_printer *p)
 {
-	struct intel_runtime_pm_debug dbg = {};
+	struct intel_wakeref_tracker dbg = {};
 
 	do {
 		unsigned long alloc = dbg.count;
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
index e592e8d6499a1f..a8dc2baf79844f 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.h
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
@@ -83,15 +83,7 @@ struct intel_runtime_pm {
 	 * paired rpm_put) we can remove corresponding pairs of and keep
 	 * the array trimmed to active wakerefs.
 	 */
-	struct intel_runtime_pm_debug {
-		spinlock_t lock;
-
-		depot_stack_handle_t last_acquire;
-		depot_stack_handle_t last_release;
-
-		depot_stack_handle_t *owners;
-		unsigned long count;
-	} debug;
+	struct intel_wakeref_tracker debug;
 #endif
 };
 
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index 71b8a63f6f104d..583fdaadd9912c 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -17,6 +17,8 @@
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 
+#include "intel_wakeref_tracker.h"
+
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
 #define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
 #else
@@ -26,8 +28,6 @@
 struct intel_runtime_pm;
 struct intel_wakeref;
 
-typedef depot_stack_handle_t intel_wakeref_t;
-
 struct intel_wakeref_ops {
 	int (*get)(struct intel_wakeref *wf);
 	int (*put)(struct intel_wakeref *wf);
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.h b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
new file mode 100644
index 00000000000000..74e6261fb31260
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef INTEL_WAKEREF_TRACKER_H
+#define INTEL_WAKEREF_TRACKER_H
+
+#include <linux/spinlock.h>
+#include <linux/stackdepot.h>
+
+typedef depot_stack_handle_t intel_wakeref_t;
+
+struct intel_wakeref_tracker {
+	spinlock_t lock;
+
+	depot_stack_handle_t last_acquire;
+	depot_stack_handle_t last_release;
+
+	depot_stack_handle_t *owners;
+	unsigned long count;
+};
+
+#endif /* INTEL_WAKEREF_TRACKER_H */

-- 
2.34.1

[PATCH v4 06/10] drm/i915: Separate wakeref tracking

[Andrzej Hajda]

From: Chris Wilson <chris@chris-wilson.co.uk>

Extract the callstack tracking of intel_runtime_pm.c into its own
utility so that that we can reuse it for other online debugging of
scoped wakerefs.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/Kconfig.debug           |   9 ++
 drivers/gpu/drm/i915/Makefile                |   4 +
 drivers/gpu/drm/i915/intel_runtime_pm.c      | 222 +++----------------------
 drivers/gpu/drm/i915/intel_wakeref.h         |   2 +-
 drivers/gpu/drm/i915/intel_wakeref_tracker.c | 234 +++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_wakeref_tracker.h |  52 ++++++
 6 files changed, 319 insertions(+), 204 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index 93dfb7ed970547..5fde52107e3b44 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -25,6 +25,7 @@ config DRM_I915_DEBUG
 	select PREEMPT_COUNT
 	select I2C_CHARDEV
 	select STACKDEPOT
+	select STACKTRACE
 	select DRM_DP_AUX_CHARDEV
 	select X86_MSR # used by igt/pm_rpm
 	select DRM_VGEM # used by igt/prime_vgem (dmabuf interop checks)
@@ -37,6 +38,7 @@ config DRM_I915_DEBUG
 	select DRM_I915_DEBUG_GEM
 	select DRM_I915_DEBUG_GEM_ONCE
 	select DRM_I915_DEBUG_MMIO
+	select DRM_I915_TRACK_WAKEREF
 	select DRM_I915_DEBUG_RUNTIME_PM
 	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
 	select DRM_I915_SELFTEST
@@ -227,11 +229,18 @@ config DRM_I915_DEBUG_VBLANK_EVADE
 
 	  If in doubt, say "N".
 
+config DRM_I915_TRACK_WAKEREF
+	depends on STACKDEPOT
+	depends on STACKTRACE
+	bool
+
 config DRM_I915_DEBUG_RUNTIME_PM
 	bool "Enable extra state checking for runtime PM"
 	depends on DRM_I915
 	default n
 	select STACKDEPOT
+	select STACKTRACE
+	select DRM_I915_TRACK_WAKEREF
 	help
 	  Choose this option to turn on extra state checking for the
 	  runtime PM functionality. This may introduce overhead during
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index b2f91a1f826858..42daff6d575a82 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -81,6 +81,10 @@ i915-$(CONFIG_DEBUG_FS) += \
 	i915_debugfs_params.o \
 	display/intel_display_debugfs.o \
 	display/intel_pipe_crc.o
+
+i915-$(CONFIG_DRM_I915_TRACK_WAKEREF) += \
+	intel_wakeref_tracker.o
+
 i915-$(CONFIG_PERF_EVENTS) += i915_pmu.o
 
 # "Graphics Technology" (aka we talk to the gpu)
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 1901eedb6704a2..43149cf12dc864 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -52,182 +52,37 @@
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
 
-#include <linux/sort.h>
-
-#define STACKDEPTH 8
-
-static noinline depot_stack_handle_t __save_depot_stack(void)
-{
-	unsigned long entries[STACKDEPTH];
-	unsigned int n;
-
-	n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
-	return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
-}
-
 static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
-	spin_lock_init(&rpm->debug.lock);
-	stack_depot_init();
+	intel_wakeref_tracker_init(&rpm->debug);
 }
 
-static noinline depot_stack_handle_t
+static intel_wakeref_t
 track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
-	depot_stack_handle_t stack, *stacks;
-	unsigned long flags;
-
-	if (rpm->no_wakeref_tracking)
-		return -1;
-
-	stack = __save_depot_stack();
-	if (!stack)
+	if (!rpm->available || rpm->no_wakeref_tracking)
 		return -1;
 
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-
-	if (!rpm->debug.count)
-		rpm->debug.last_acquire = stack;
-
-	stacks = krealloc(rpm->debug.owners,
-			  (rpm->debug.count + 1) * sizeof(*stacks),
-			  GFP_NOWAIT | __GFP_NOWARN);
-	if (stacks) {
-		stacks[rpm->debug.count++] = stack;
-		rpm->debug.owners = stacks;
-	} else {
-		stack = -1;
-	}
-
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	return stack;
+	return intel_wakeref_tracker_add(&rpm->debug);
 }
 
 static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
-					     depot_stack_handle_t stack)
+					     intel_wakeref_t wakeref)
 {
-	struct drm_i915_private *i915 = container_of(rpm,
-						     struct drm_i915_private,
-						     runtime_pm);
-	unsigned long flags, n;
-	bool found = false;
-
-	if (unlikely(stack == -1))
-		return;
-
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-	for (n = rpm->debug.count; n--; ) {
-		if (rpm->debug.owners[n] == stack) {
-			memmove(rpm->debug.owners + n,
-				rpm->debug.owners + n + 1,
-				(--rpm->debug.count - n) * sizeof(stack));
-			found = true;
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	if (drm_WARN(&i915->drm, !found,
-		     "Unmatched wakeref (tracking %lu), count %u\n",
-		     rpm->debug.count, atomic_read(&rpm->wakeref_count))) {
-		char *buf;
-
-		buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-		if (!buf)
-			return;
-
-		stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-		DRM_DEBUG_DRIVER("wakeref %x from\n%s", stack, buf);
-
-		stack = READ_ONCE(rpm->debug.last_release);
-		if (stack) {
-			stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-			DRM_DEBUG_DRIVER("wakeref last released at\n%s", buf);
-		}
-
-		kfree(buf);
-	}
+	intel_wakeref_tracker_remove(&rpm->debug, wakeref);
 }
 
-static int cmphandle(const void *_a, const void *_b)
+static void untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
 {
-	const depot_stack_handle_t * const a = _a, * const b = _b;
+	struct drm_printer p = drm_debug_printer("i915");
 
-	if (*a < *b)
-		return -1;
-	else if (*a > *b)
-		return 1;
-	else
-		return 0;
-}
-
-static void
-__print_intel_runtime_pm_wakeref(struct drm_printer *p,
-				 const struct intel_wakeref_tracker *dbg)
-{
-	unsigned long i;
-	char *buf;
-
-	buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-	if (!buf)
-		return;
-
-	if (dbg->last_acquire) {
-		stack_depot_snprint(dbg->last_acquire, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last acquired:\n%s", buf);
-	}
-
-	if (dbg->last_release) {
-		stack_depot_snprint(dbg->last_release, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last released:\n%s", buf);
-	}
-
-	drm_printf(p, "Wakeref count: %lu\n", dbg->count);
-
-	sort(dbg->owners, dbg->count, sizeof(*dbg->owners), cmphandle, NULL);
-
-	for (i = 0; i < dbg->count; i++) {
-		depot_stack_handle_t stack = dbg->owners[i];
-		unsigned long rep;
-
-		rep = 1;
-		while (i + 1 < dbg->count && dbg->owners[i + 1] == stack)
-			rep++, i++;
-		stack_depot_snprint(stack, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
-	}
-
-	kfree(buf);
-}
-
-static noinline void
-__untrack_all_wakerefs(struct intel_wakeref_tracker *debug,
-		       struct intel_wakeref_tracker *saved)
-{
-	*saved = *debug;
-
-	debug->owners = NULL;
-	debug->count = 0;
-	debug->last_release = __save_depot_stack();
-}
-
-static void
-dump_and_free_wakeref_tracking(struct intel_wakeref_tracker *debug)
-{
-	if (debug->count) {
-		struct drm_printer p = drm_debug_printer("i915");
-
-		__print_intel_runtime_pm_wakeref(&p, debug);
-	}
-
-	kfree(debug->owners);
+	intel_wakeref_tracker_reset(&rpm->debug, &p);
 }
 
 static noinline void
 __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 {
-	struct intel_wakeref_tracker dbg = {};
+	struct intel_wakeref_tracker saved;
 	unsigned long flags;
 
 	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
@@ -235,60 +90,21 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 					 flags))
 		return;
 
-	__untrack_all_wakerefs(&rpm->debug, &dbg);
+	saved = __intel_wakeref_tracker_reset(&rpm->debug);
 	spin_unlock_irqrestore(&rpm->debug.lock, flags);
 
-	dump_and_free_wakeref_tracking(&dbg);
-}
-
-static noinline void
-untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
-{
-	struct intel_wakeref_tracker dbg = {};
-	unsigned long flags;
-
-	spin_lock_irqsave(&rpm->debug.lock, flags);
-	__untrack_all_wakerefs(&rpm->debug, &dbg);
-	spin_unlock_irqrestore(&rpm->debug.lock, flags);
+	if (saved.count) {
+		struct drm_printer p = drm_debug_printer("i915");
 
-	dump_and_free_wakeref_tracking(&dbg);
+		__intel_wakeref_tracker_show(&saved, &p);
+		intel_wakeref_tracker_fini(&saved);
+	}
 }
 
 void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
 				    struct drm_printer *p)
 {
-	struct intel_wakeref_tracker dbg = {};
-
-	do {
-		unsigned long alloc = dbg.count;
-		depot_stack_handle_t *s;
-
-		spin_lock_irq(&rpm->debug.lock);
-		dbg.count = rpm->debug.count;
-		if (dbg.count <= alloc) {
-			memcpy(dbg.owners,
-			       rpm->debug.owners,
-			       dbg.count * sizeof(*s));
-		}
-		dbg.last_acquire = rpm->debug.last_acquire;
-		dbg.last_release = rpm->debug.last_release;
-		spin_unlock_irq(&rpm->debug.lock);
-		if (dbg.count <= alloc)
-			break;
-
-		s = krealloc(dbg.owners,
-			     dbg.count * sizeof(*s),
-			     GFP_NOWAIT | __GFP_NOWARN);
-		if (!s)
-			goto out;
-
-		dbg.owners = s;
-	} while (1);
-
-	__print_intel_runtime_pm_wakeref(p, &dbg);
-
-out:
-	kfree(dbg.owners);
+	intel_wakeref_tracker_show(&rpm->debug, p);
 }
 
 #else
@@ -297,14 +113,14 @@ static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
 }
 
-static depot_stack_handle_t
+static intel_wakeref_t
 track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
 	return -1;
 }
 
 static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
-					     intel_wakeref_t wref)
+					     intel_wakeref_t wakeref)
 {
 }
 
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index 583fdaadd9912c..20720fbcc28d46 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -19,7 +19,7 @@
 
 #include "intel_wakeref_tracker.h"
 
-#if IS_ENABLED(CONFIG_DRM_I915_DEBUG)
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 #define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
 #else
 #define INTEL_WAKEREF_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.c b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
new file mode 100644
index 00000000000000..c92035030a75cc
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/slab.h>
+#include <linux/stackdepot.h>
+#include <linux/stacktrace.h>
+#include <linux/sort.h>
+
+#include <drm/drm_print.h>
+
+#include "intel_wakeref_tracker.h"
+
+#define STACKDEPTH 8
+
+static noinline depot_stack_handle_t __save_depot_stack(void)
+{
+	unsigned long entries[STACKDEPTH];
+	unsigned int n;
+
+	n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
+	return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
+}
+
+static void __print_depot_stack(depot_stack_handle_t stack,
+				char *buf, int sz, int indent)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(stack, &entries);
+	stack_trace_snprint(buf, sz, entries, nr_entries, indent);
+}
+
+static int cmphandle(const void *_a, const void *_b)
+{
+	const depot_stack_handle_t * const a = _a, * const b = _b;
+
+	if (*a < *b)
+		return -1;
+	else if (*a > *b)
+		return 1;
+	else
+		return 0;
+}
+
+void
+__intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
+			     struct drm_printer *p)
+{
+	unsigned long i;
+	char *buf;
+
+	buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
+	if (!buf)
+		return;
+
+	if (w->last_acquire) {
+		__print_depot_stack(w->last_acquire, buf, PAGE_SIZE, 2);
+		drm_printf(p, "Wakeref last acquired:\n%s", buf);
+	}
+
+	if (w->last_release) {
+		__print_depot_stack(w->last_release, buf, PAGE_SIZE, 2);
+		drm_printf(p, "Wakeref last released:\n%s", buf);
+	}
+
+	drm_printf(p, "Wakeref count: %lu\n", w->count);
+
+	sort(w->owners, w->count, sizeof(*w->owners), cmphandle, NULL);
+
+	for (i = 0; i < w->count; i++) {
+		depot_stack_handle_t stack = w->owners[i];
+		unsigned long rep;
+
+		rep = 1;
+		while (i + 1 < w->count && w->owners[i + 1] == stack)
+			rep++, i++;
+		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
+		drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
+	}
+
+	kfree(buf);
+}
+
+void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
+				struct drm_printer *p)
+{
+	struct intel_wakeref_tracker tmp = {};
+
+	do {
+		unsigned long alloc = tmp.count;
+		depot_stack_handle_t *s;
+
+		spin_lock_irq(&w->lock);
+		tmp.count = w->count;
+		if (tmp.count <= alloc)
+			memcpy(tmp.owners, w->owners, tmp.count * sizeof(*s));
+		tmp.last_acquire = w->last_acquire;
+		tmp.last_release = w->last_release;
+		spin_unlock_irq(&w->lock);
+		if (tmp.count <= alloc)
+			break;
+
+		s = krealloc(tmp.owners,
+			     tmp.count * sizeof(*s),
+			     GFP_NOWAIT | __GFP_NOWARN);
+		if (!s)
+			goto out;
+
+		tmp.owners = s;
+	} while (1);
+
+	__intel_wakeref_tracker_show(&tmp, p);
+
+out:
+	intel_wakeref_tracker_fini(&tmp);
+}
+
+intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
+{
+	depot_stack_handle_t stack, *stacks;
+	unsigned long flags;
+
+	stack = __save_depot_stack();
+	if (!stack)
+		return -1;
+
+	spin_lock_irqsave(&w->lock, flags);
+
+	if (!w->count)
+		w->last_acquire = stack;
+
+	stacks = krealloc(w->owners,
+			  (w->count + 1) * sizeof(*stacks),
+			  GFP_NOWAIT | __GFP_NOWARN);
+	if (stacks) {
+		stacks[w->count++] = stack;
+		w->owners = stacks;
+	} else {
+		stack = -1;
+	}
+
+	spin_unlock_irqrestore(&w->lock, flags);
+
+	return stack;
+}
+
+void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
+				  intel_wakeref_t stack)
+{
+	unsigned long flags, n;
+	bool found = false;
+
+	if (unlikely(stack == -1))
+		return;
+
+	spin_lock_irqsave(&w->lock, flags);
+	for (n = w->count; n--; ) {
+		if (w->owners[n] == stack) {
+			memmove(w->owners + n,
+				w->owners + n + 1,
+				(--w->count - n) * sizeof(stack));
+			found = true;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&w->lock, flags);
+
+	if (WARN(!found,
+		 "Unmatched wakeref %x, tracking %lu\n",
+		 stack, w->count)) {
+		char *buf;
+
+		buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
+		if (!buf)
+			return;
+
+		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
+		pr_err("wakeref %x from\n%s", stack, buf);
+
+		stack = READ_ONCE(w->last_release);
+		if (stack && !w->count) {
+			__print_depot_stack(stack, buf, PAGE_SIZE, 2);
+			pr_err("wakeref last released at\n%s", buf);
+		}
+
+		kfree(buf);
+	}
+}
+
+struct intel_wakeref_tracker
+__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
+{
+	struct intel_wakeref_tracker saved;
+
+	lockdep_assert_held(&w->lock);
+
+	saved = *w;
+
+	w->owners = NULL;
+	w->count = 0;
+	w->last_release = __save_depot_stack();
+
+	return saved;
+}
+
+void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
+				 struct drm_printer *p)
+{
+	struct intel_wakeref_tracker tmp;
+
+	spin_lock_irq(&w->lock);
+	tmp = __intel_wakeref_tracker_reset(w);
+	spin_unlock_irq(&w->lock);
+
+	if (tmp.count)
+		__intel_wakeref_tracker_show(&tmp, p);
+
+	intel_wakeref_tracker_fini(&tmp);
+}
+
+void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w)
+{
+	memset(w, 0, sizeof(*w));
+	spin_lock_init(&w->lock);
+	stack_depot_init();
+}
+
+void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w)
+{
+	kfree(w->owners);
+}
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.h b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
index 74e6261fb31260..61df68e28c0fbf 100644
--- a/drivers/gpu/drm/i915/intel_wakeref_tracker.h
+++ b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
@@ -6,11 +6,14 @@
 #ifndef INTEL_WAKEREF_TRACKER_H
 #define INTEL_WAKEREF_TRACKER_H
 
+#include <linux/kconfig.h>
 #include <linux/spinlock.h>
 #include <linux/stackdepot.h>
 
 typedef depot_stack_handle_t intel_wakeref_t;
 
+struct drm_printer;
+
 struct intel_wakeref_tracker {
 	spinlock_t lock;
 
@@ -21,4 +24,53 @@ struct intel_wakeref_tracker {
 	unsigned long count;
 };
 
+#if IS_ENABLED(CONFIG_DRM_I915_TRACK_WAKEREF)
+
+void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w);
+void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w);
+
+intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w);
+void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
+			   intel_wakeref_t handle);
+
+struct intel_wakeref_tracker
+__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w);
+void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
+				 struct drm_printer *p);
+
+void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
+				  struct drm_printer *p);
+void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
+				struct drm_printer *p);
+
+#else
+
+static inline void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w) {}
+static inline void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w) {}
+
+static inline intel_wakeref_t
+intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
+{
+	return -1;
+}
+
+static inline void
+intel_wakeref_untrack_remove(struct intel_wakeref_tracker *w, intel_wakeref_t handle) {}
+
+static inline struct intel_wakeref_tracker
+__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
+{
+	return (struct intel_wakeref_tracker){};
+}
+
+static inline void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
+					       struct drm_printer *p)
+{
+}
+
+static inline void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w, struct drm_printer *p) {}
+static inline void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w, struct drm_printer *p) {}
+
+#endif
+
 #endif /* INTEL_WAKEREF_TRACKER_H */

-- 
2.34.1

[PATCH v4 07/10] drm/i915: Track leaked gt->wakerefs

[Andrzej Hajda]

From: Chris Wilson <chris.p.wilson@intel.com>

Track every intel_gt_pm_get() until its corresponding release in
intel_gt_pm_put() by returning a cookie to the caller for acquire that
must be passed by on rleased. When there is an imbalance, we can see who
either tried to free a stale wakeref, or who forgot to free theirs.

v2: Rebase from backporting wakeref leak (Umesh)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/Kconfig.debug                 | 15 ++++++++
 drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c     |  7 ++--
 .../drm/i915/gem/selftests/i915_gem_coherency.c    | 10 +++---
 drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c | 14 ++++----
 drivers/gpu/drm/i915/gt/intel_breadcrumbs.c        | 13 ++++---
 drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h  |  3 +-
 drivers/gpu/drm/i915/gt/intel_engine_pm.c          |  4 +--
 drivers/gpu/drm/i915/gt/intel_engine_types.h       |  2 ++
 .../gpu/drm/i915/gt/intel_execlists_submission.c   |  2 +-
 drivers/gpu/drm/i915/gt/intel_gt_pm.c              | 10 +++---
 drivers/gpu/drm/i915/gt/intel_gt_pm.h              | 38 +++++++++++++++-----
 drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c      |  4 +--
 drivers/gpu/drm/i915/gt/selftest_engine_cs.c       | 20 ++++++-----
 drivers/gpu/drm/i915/gt/selftest_gt_pm.c           |  5 +--
 drivers/gpu/drm/i915/gt/selftest_reset.c           | 10 +++---
 drivers/gpu/drm/i915/gt/selftest_rps.c             | 17 +++++----
 drivers/gpu/drm/i915/gt/selftest_slpc.c            |  5 +--
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c  |  9 ++---
 drivers/gpu/drm/i915/i915_pmu.c                    | 16 +++++----
 drivers/gpu/drm/i915/intel_wakeref.c               |  4 +++
 drivers/gpu/drm/i915/intel_wakeref.h               | 42 ++++++++++++++++++++++
 21 files changed, 180 insertions(+), 70 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index 5fde52107e3b44..63b77dc48d4394 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -40,6 +40,7 @@ config DRM_I915_DEBUG
 	select DRM_I915_DEBUG_MMIO
 	select DRM_I915_TRACK_WAKEREF
 	select DRM_I915_DEBUG_RUNTIME_PM
+	select DRM_I915_DEBUG_WAKEREF
 	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
 	select DRM_I915_SELFTEST
 	select BROKEN # for prototype uAPI
@@ -249,3 +250,17 @@ config DRM_I915_DEBUG_RUNTIME_PM
 	  Recommended for driver developers only.
 
 	  If in doubt, say "N"
+
+config DRM_I915_DEBUG_WAKEREF
+	bool "Enable extra tracking for wakerefs"
+	depends on DRM_I915
+	default n
+	select STACKDEPOT
+	select STACKTRACE
+	select DRM_I915_TRACK_WAKEREF
+	help
+	  Choose this option to turn on extra state checking and usage
+	  tracking for the wakerefPM functionality. This may introduce
+	  overhead during driver runtime.
+
+	  If in doubt, say "N"
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 9dce2957b4e5ae..65abcd82b6de93 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -253,6 +253,7 @@ struct i915_execbuffer {
 	struct intel_gt *gt; /* gt for the execbuf */
 	struct intel_context *context; /* logical state for the request */
 	struct i915_gem_context *gem_context; /** caller's context */
+	intel_wakeref_t wakeref;
 
 	/** our requests to build */
 	struct i915_request *requests[MAX_ENGINE_INSTANCE + 1];
@@ -2713,7 +2714,7 @@ eb_select_engine(struct i915_execbuffer *eb)
 
 	for_each_child(ce, child)
 		intel_context_get(child);
-	intel_gt_pm_get(ce->engine->gt);
+	eb->wakeref = intel_gt_pm_get(ce->engine->gt);
 
 	if (!test_bit(CONTEXT_ALLOC_BIT, &ce->flags)) {
 		err = intel_context_alloc_state(ce);
@@ -2752,7 +2753,7 @@ eb_select_engine(struct i915_execbuffer *eb)
 	return err;
 
 err:
-	intel_gt_pm_put(ce->engine->gt);
+	intel_gt_pm_put(ce->engine->gt, eb->wakeref);
 	for_each_child(ce, child)
 		intel_context_put(child);
 	intel_context_put(ce);
@@ -2765,7 +2766,7 @@ eb_put_engine(struct i915_execbuffer *eb)
 	struct intel_context *child;
 
 	i915_vm_put(eb->context->vm);
-	intel_gt_pm_put(eb->gt);
+	intel_gt_pm_put(eb->context->engine->gt, eb->wakeref);
 	for_each_child(eb->context, child)
 		intel_context_put(child);
 	intel_context_put(eb->context);
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
index 3bef1beec7cbb5..3fd68a099a85ef 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -85,6 +85,7 @@ static int cpu_get(struct context *ctx, unsigned long offset, u32 *v)
 
 static int gtt_set(struct context *ctx, unsigned long offset, u32 v)
 {
+	intel_wakeref_t wakeref;
 	struct i915_vma *vma;
 	u32 __iomem *map;
 	int err = 0;
@@ -99,7 +100,7 @@ static int gtt_set(struct context *ctx, unsigned long offset, u32 v)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	intel_gt_pm_get(vma->vm->gt);
+	wakeref = intel_gt_pm_get(vma->vm->gt);
 
 	map = i915_vma_pin_iomap(vma);
 	i915_vma_unpin(vma);
@@ -112,12 +113,13 @@ static int gtt_set(struct context *ctx, unsigned long offset, u32 v)
 	i915_vma_unpin_iomap(vma);
 
 out_rpm:
-	intel_gt_pm_put(vma->vm->gt);
+	intel_gt_pm_put(vma->vm->gt, wakeref);
 	return err;
 }
 
 static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
 {
+	intel_wakeref_t wakeref;
 	struct i915_vma *vma;
 	u32 __iomem *map;
 	int err = 0;
@@ -132,7 +134,7 @@ static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	intel_gt_pm_get(vma->vm->gt);
+	wakeref = intel_gt_pm_get(vma->vm->gt);
 
 	map = i915_vma_pin_iomap(vma);
 	i915_vma_unpin(vma);
@@ -145,7 +147,7 @@ static int gtt_get(struct context *ctx, unsigned long offset, u32 *v)
 	i915_vma_unpin_iomap(vma);
 
 out_rpm:
-	intel_gt_pm_put(vma->vm->gt);
+	intel_gt_pm_put(vma->vm->gt, wakeref);
 	return err;
 }
 
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
index 56279908ed305b..f6f36a85688814 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c
@@ -630,14 +630,14 @@ static bool assert_mmap_offset(struct drm_i915_private *i915,
 static void disable_retire_worker(struct drm_i915_private *i915)
 {
 	i915_gem_driver_unregister__shrinker(i915);
-	intel_gt_pm_get(to_gt(i915));
+	intel_gt_pm_get_untracked(to_gt(i915));
 	cancel_delayed_work_sync(&to_gt(i915)->requests.retire_work);
 }
 
 static void restore_retire_worker(struct drm_i915_private *i915)
 {
 	igt_flush_test(i915);
-	intel_gt_pm_put(to_gt(i915));
+	intel_gt_pm_put_untracked(to_gt(i915));
 	i915_gem_driver_register__shrinker(i915);
 }
 
@@ -778,6 +778,7 @@ static int igt_mmap_offset_exhaustion(void *arg)
 
 static int gtt_set(struct drm_i915_gem_object *obj)
 {
+	intel_wakeref_t wakeref;
 	struct i915_vma *vma;
 	void __iomem *map;
 	int err = 0;
@@ -786,7 +787,7 @@ static int gtt_set(struct drm_i915_gem_object *obj)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	intel_gt_pm_get(vma->vm->gt);
+	wakeref = intel_gt_pm_get(vma->vm->gt);
 	map = i915_vma_pin_iomap(vma);
 	i915_vma_unpin(vma);
 	if (IS_ERR(map)) {
@@ -798,12 +799,13 @@ static int gtt_set(struct drm_i915_gem_object *obj)
 	i915_vma_unpin_iomap(vma);
 
 out:
-	intel_gt_pm_put(vma->vm->gt);
+	intel_gt_pm_put(vma->vm->gt, wakeref);
 	return err;
 }
 
 static int gtt_check(struct drm_i915_gem_object *obj)
 {
+	intel_wakeref_t wakeref;
 	struct i915_vma *vma;
 	void __iomem *map;
 	int err = 0;
@@ -812,7 +814,7 @@ static int gtt_check(struct drm_i915_gem_object *obj)
 	if (IS_ERR(vma))
 		return PTR_ERR(vma);
 
-	intel_gt_pm_get(vma->vm->gt);
+	wakeref = intel_gt_pm_get(vma->vm->gt);
 	map = i915_vma_pin_iomap(vma);
 	i915_vma_unpin(vma);
 	if (IS_ERR(map)) {
@@ -828,7 +830,7 @@ static int gtt_check(struct drm_i915_gem_object *obj)
 	i915_vma_unpin_iomap(vma);
 
 out:
-	intel_gt_pm_put(vma->vm->gt);
+	intel_gt_pm_put(vma->vm->gt, wakeref);
 	return err;
 }
 
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
index ecc990ec1b9526..d650beb8ed22f6 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs.c
@@ -28,11 +28,14 @@ static void irq_disable(struct intel_breadcrumbs *b)
 
 static void __intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b)
 {
+	intel_wakeref_t wakeref;
+
 	/*
 	 * Since we are waiting on a request, the GPU should be busy
 	 * and should have its own rpm reference.
 	 */
-	if (GEM_WARN_ON(!intel_gt_pm_get_if_awake(b->irq_engine->gt)))
+	wakeref = intel_gt_pm_get_if_awake(b->irq_engine->gt);
+	if (GEM_WARN_ON(!wakeref))
 		return;
 
 	/*
@@ -41,7 +44,7 @@ static void __intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b)
 	 * which we can add a new waiter and avoid the cost of re-enabling
 	 * the irq.
 	 */
-	WRITE_ONCE(b->irq_armed, true);
+	WRITE_ONCE(b->irq_armed, wakeref);
 
 	/* Requests may have completed before we could enable the interrupt. */
 	if (!b->irq_enabled++ && b->irq_enable(b))
@@ -61,12 +64,14 @@ static void intel_breadcrumbs_arm_irq(struct intel_breadcrumbs *b)
 
 static void __intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b)
 {
+	intel_wakeref_t wakeref = b->irq_armed;
+
 	GEM_BUG_ON(!b->irq_enabled);
 	if (!--b->irq_enabled)
 		b->irq_disable(b);
 
-	WRITE_ONCE(b->irq_armed, false);
-	intel_gt_pm_put_async(b->irq_engine->gt);
+	WRITE_ONCE(b->irq_armed, 0);
+	intel_gt_pm_put_async(b->irq_engine->gt, wakeref);
 }
 
 static void intel_breadcrumbs_disarm_irq(struct intel_breadcrumbs *b)
diff --git a/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h b/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h
index 72dfd3748c4c33..bdf09fd67b6e70 100644
--- a/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 
 #include "intel_engine_types.h"
+#include "intel_wakeref.h"
 
 /*
  * Rather than have every client wait upon all user interrupts,
@@ -43,7 +44,7 @@ struct intel_breadcrumbs {
 	spinlock_t irq_lock; /* protects the interrupt from hardirq context */
 	struct irq_work irq_work; /* for use from inside irq_lock */
 	unsigned int irq_enabled;
-	bool irq_armed;
+	intel_wakeref_t irq_armed;
 
 	/* Not all breadcrumbs are attached to physical HW */
 	intel_engine_mask_t	engine_mask;
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index e971b153fda976..7db9229d28639c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -63,7 +63,7 @@ static int __engine_unpark(struct intel_wakeref *wf)
 
 	ENGINE_TRACE(engine, "\n");
 
-	intel_gt_pm_get(engine->gt);
+	engine->wakeref_track = intel_gt_pm_get(engine->gt);
 
 	/* Discard stale context state from across idling */
 	ce = engine->kernel_context;
@@ -276,7 +276,7 @@ static int __engine_park(struct intel_wakeref *wf)
 		engine->park(engine);
 
 	/* While gt calls i915_vma_parked(), we have to break the lock cycle */
-	intel_gt_pm_put_async(engine->gt);
+	intel_gt_pm_put_async(engine->gt, engine->wakeref_track);
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index 0a071e5da1a85d..2791d487ab114c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -431,7 +431,9 @@ struct intel_engine_cs {
 	unsigned long serial;
 
 	unsigned long wakeref_serial;
+	intel_wakeref_t wakeref_track;
 	struct intel_wakeref wakeref;
+
 	struct file *default_state;
 
 	struct {
diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
index 3c573d41d40468..80d90aa305f1ea 100644
--- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
+++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
@@ -630,7 +630,7 @@ static void __execlists_schedule_out(struct i915_request * const rq,
 	execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT);
 	if (engine->fw_domain && !--engine->fw_active)
 		intel_uncore_forcewake_put(engine->uncore, engine->fw_domain);
-	intel_gt_pm_put_async(engine->gt);
+	intel_gt_pm_put_async_untracked(engine->gt);
 
 	/*
 	 * If this is part of a virtual engine, its next request may
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index cef3d6f5c34e01..302f908b37fb2e 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -49,19 +49,20 @@ static void mtl_media_idle(struct intel_gt *gt)
 static void user_forcewake(struct intel_gt *gt, bool suspend)
 {
 	int count = atomic_read(&gt->user_wakeref);
+	intel_wakeref_t wakeref;
 
 	/* Inside suspend/resume so single threaded, no races to worry about. */
 	if (likely(!count))
 		return;
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	if (suspend) {
 		GEM_BUG_ON(count > atomic_read(&gt->wakeref.count));
 		atomic_sub(count, &gt->wakeref.count);
 	} else {
 		atomic_add(count, &gt->wakeref.count);
 	}
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 }
 
 static void runtime_begin(struct intel_gt *gt)
@@ -248,6 +249,7 @@ int intel_gt_resume(struct intel_gt *gt)
 {
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	int err;
 
 	err = intel_gt_has_unrecoverable_error(gt);
@@ -264,7 +266,7 @@ int intel_gt_resume(struct intel_gt *gt)
 	 */
 	gt_sanitize(gt, true);
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 
 	intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);
 	intel_rc6_sanitize(&gt->rc6);
@@ -307,7 +309,7 @@ int intel_gt_resume(struct intel_gt *gt)
 
 out_fw:
 	intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 	return err;
 
 err_wedged:
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
index 6c9a4645236467..2ae5fbbede6ca8 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
@@ -16,19 +16,28 @@ static inline bool intel_gt_pm_is_awake(const struct intel_gt *gt)
 	return intel_wakeref_is_active(&gt->wakeref);
 }
 
-static inline void intel_gt_pm_get(struct intel_gt *gt)
+static inline void intel_gt_pm_get_untracked(struct intel_gt *gt)
 {
 	intel_wakeref_get(&gt->wakeref);
 }
 
+static inline intel_wakeref_t intel_gt_pm_get(struct intel_gt *gt)
+{
+	intel_gt_pm_get_untracked(gt);
+	return intel_wakeref_track(&gt->wakeref);
+}
+
 static inline void __intel_gt_pm_get(struct intel_gt *gt)
 {
 	__intel_wakeref_get(&gt->wakeref);
 }
 
-static inline bool intel_gt_pm_get_if_awake(struct intel_gt *gt)
+static inline intel_wakeref_t intel_gt_pm_get_if_awake(struct intel_gt *gt)
 {
-	return intel_wakeref_get_if_active(&gt->wakeref);
+	if (!intel_wakeref_get_if_active(&gt->wakeref))
+		return 0;
+
+	return intel_wakeref_track(&gt->wakeref);
 }
 
 static inline void intel_gt_pm_might_get(struct intel_gt *gt)
@@ -36,12 +45,18 @@ static inline void intel_gt_pm_might_get(struct intel_gt *gt)
 	intel_wakeref_might_get(&gt->wakeref);
 }
 
-static inline void intel_gt_pm_put(struct intel_gt *gt)
+static inline void intel_gt_pm_put_untracked(struct intel_gt *gt)
 {
 	intel_wakeref_put(&gt->wakeref);
 }
 
-static inline void intel_gt_pm_put_async(struct intel_gt *gt)
+static inline void intel_gt_pm_put(struct intel_gt *gt, intel_wakeref_t handle)
+{
+	intel_wakeref_untrack(&gt->wakeref, handle);
+	intel_gt_pm_put_untracked(gt);
+}
+
+static inline void intel_gt_pm_put_async_untracked(struct intel_gt *gt)
 {
 	intel_wakeref_put_async(&gt->wakeref);
 }
@@ -51,9 +66,14 @@ static inline void intel_gt_pm_might_put(struct intel_gt *gt)
 	intel_wakeref_might_put(&gt->wakeref);
 }
 
-#define with_intel_gt_pm(gt, tmp) \
-	for (tmp = 1, intel_gt_pm_get(gt); tmp; \
-	     intel_gt_pm_put(gt), tmp = 0)
+static inline void intel_gt_pm_put_async(struct intel_gt *gt, intel_wakeref_t handle)
+{
+	intel_wakeref_untrack(&gt->wakeref, handle);
+	intel_gt_pm_put_async_untracked(gt);
+}
+
+#define with_intel_gt_pm(gt, wf) \
+	for (wf = intel_gt_pm_get(gt); wf; intel_gt_pm_put(gt, wf), wf = 0)
 
 /**
  * with_intel_gt_pm_if_awake - if GT is PM awake, get a reference to prevent
@@ -64,7 +84,7 @@ static inline void intel_gt_pm_might_put(struct intel_gt *gt)
  * @wf: pointer to a temporary wakeref.
  */
 #define with_intel_gt_pm_if_awake(gt, wf) \
-	for (wf = intel_gt_pm_get_if_awake(gt); wf; intel_gt_pm_put_async(gt), wf = 0)
+	for (wf = intel_gt_pm_get_if_awake(gt); wf; intel_gt_pm_put_async(gt, wf), wf = 0)
 
 static inline int intel_gt_pm_wait_for_idle(struct intel_gt *gt)
 {
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
index 83df4cd5e06cb9..0f5ba4491e4de8 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c
@@ -27,7 +27,7 @@
 void intel_gt_pm_debugfs_forcewake_user_open(struct intel_gt *gt)
 {
 	atomic_inc(&gt->user_wakeref);
-	intel_gt_pm_get(gt);
+	intel_gt_pm_get_untracked(gt);
 	if (GRAPHICS_VER(gt->i915) >= 6)
 		intel_uncore_forcewake_user_get(gt->uncore);
 }
@@ -36,7 +36,7 @@ void intel_gt_pm_debugfs_forcewake_user_release(struct intel_gt *gt)
 {
 	if (GRAPHICS_VER(gt->i915) >= 6)
 		intel_uncore_forcewake_user_put(gt->uncore);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put_untracked(gt);
 	atomic_dec(&gt->user_wakeref);
 }
 
diff --git a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
index 542ce6d2de1922..f3d21bdfd7f639 100644
--- a/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/selftest_engine_cs.c
@@ -21,20 +21,22 @@ static int cmp_u32(const void *A, const void *B)
 	return *a - *b;
 }
 
-static void perf_begin(struct intel_gt *gt)
+static intel_wakeref_t perf_begin(struct intel_gt *gt)
 {
-	intel_gt_pm_get(gt);
+	intel_wakeref_t wakeref = intel_gt_pm_get(gt);
 
 	/* Boost gpufreq to max [waitboost] and keep it fixed */
 	atomic_inc(&gt->rps.num_waiters);
 	schedule_work(&gt->rps.work);
 	flush_work(&gt->rps.work);
+
+	return wakeref;
 }
 
-static int perf_end(struct intel_gt *gt)
+static int perf_end(struct intel_gt *gt, intel_wakeref_t wakeref)
 {
 	atomic_dec(&gt->rps.num_waiters);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	return igt_flush_test(gt->i915);
 }
@@ -133,12 +135,13 @@ static int perf_mi_bb_start(void *arg)
 	struct intel_gt *gt = arg;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	if (GRAPHICS_VER(gt->i915) < 4) /* Any CS_TIMESTAMP? */
 		return 0;
 
-	perf_begin(gt);
+	wakeref = perf_begin(gt);
 	for_each_engine(engine, gt, id) {
 		struct intel_context *ce = engine->kernel_context;
 		struct i915_vma *batch;
@@ -207,7 +210,7 @@ static int perf_mi_bb_start(void *arg)
 		pr_info("%s: MI_BB_START cycles: %u\n",
 			engine->name, trifilter(cycles));
 	}
-	if (perf_end(gt))
+	if (perf_end(gt, wakeref))
 		err = -EIO;
 
 	return err;
@@ -260,12 +263,13 @@ static int perf_mi_noop(void *arg)
 	struct intel_gt *gt = arg;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	if (GRAPHICS_VER(gt->i915) < 4) /* Any CS_TIMESTAMP? */
 		return 0;
 
-	perf_begin(gt);
+	wakeref = perf_begin(gt);
 	for_each_engine(engine, gt, id) {
 		struct intel_context *ce = engine->kernel_context;
 		struct i915_vma *base, *nop;
@@ -364,7 +368,7 @@ static int perf_mi_noop(void *arg)
 		pr_info("%s: 16K MI_NOOP cycles: %u\n",
 			engine->name, trifilter(cycles));
 	}
-	if (perf_end(gt))
+	if (perf_end(gt, wakeref))
 		err = -EIO;
 
 	return err;
diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
index b46425aeb2f048..23bd3ab9ddeea1 100644
--- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
@@ -81,6 +81,7 @@ static int live_gt_clocks(void *arg)
 	struct intel_gt *gt = arg;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	if (!gt->clock_frequency) { /* unknown */
@@ -91,7 +92,7 @@ static int live_gt_clocks(void *arg)
 	if (GRAPHICS_VER(gt->i915) < 4) /* Any CS_TIMESTAMP? */
 		return 0;
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	intel_uncore_forcewake_get(gt->uncore, FORCEWAKE_ALL);
 
 	for_each_engine(engine, gt, id) {
@@ -128,7 +129,7 @@ static int live_gt_clocks(void *arg)
 	}
 
 	intel_uncore_forcewake_put(gt->uncore, FORCEWAKE_ALL);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	return err;
 }
diff --git a/drivers/gpu/drm/i915/gt/selftest_reset.c b/drivers/gpu/drm/i915/gt/selftest_reset.c
index a9e0a91bc0e026..ab464cd72b8c39 100644
--- a/drivers/gpu/drm/i915/gt/selftest_reset.c
+++ b/drivers/gpu/drm/i915/gt/selftest_reset.c
@@ -257,11 +257,12 @@ static int igt_atomic_reset(void *arg)
 {
 	struct intel_gt *gt = arg;
 	const typeof(*igt_atomic_phases) *p;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	/* Check that the resets are usable from atomic context */
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	igt_global_reset_lock(gt);
 
 	/* Flush any requests before we get started and check basics */
@@ -292,7 +293,7 @@ static int igt_atomic_reset(void *arg)
 
 unlock:
 	igt_global_reset_unlock(gt);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	return err;
 }
@@ -303,6 +304,7 @@ static int igt_atomic_engine_reset(void *arg)
 	const typeof(*igt_atomic_phases) *p;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	/* Check that the resets are usable from atomic context */
@@ -313,7 +315,7 @@ static int igt_atomic_engine_reset(void *arg)
 	if (intel_uc_uses_guc_submission(&gt->uc))
 		return 0;
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	igt_global_reset_lock(gt);
 
 	/* Flush any requests before we get started and check basics */
@@ -361,7 +363,7 @@ static int igt_atomic_engine_reset(void *arg)
 
 out_unlock:
 	igt_global_reset_unlock(gt);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	return err;
 }
diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c
index 6755bbc4ebdac0..7052a52e44d74e 100644
--- a/drivers/gpu/drm/i915/gt/selftest_rps.c
+++ b/drivers/gpu/drm/i915/gt/selftest_rps.c
@@ -223,6 +223,7 @@ int live_rps_clock_interval(void *arg)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 	struct igt_spinner spin;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	if (!intel_rps_is_enabled(rps) || GRAPHICS_VER(gt->i915) < 6)
@@ -235,7 +236,7 @@ int live_rps_clock_interval(void *arg)
 	saved_work = rps->work.func;
 	rps->work.func = dummy_rps_work;
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	intel_rps_disable(&gt->rps);
 
 	intel_gt_check_clock_frequency(gt);
@@ -354,7 +355,7 @@ int live_rps_clock_interval(void *arg)
 	}
 
 	intel_rps_enable(&gt->rps);
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	igt_spinner_fini(&spin);
 
@@ -375,6 +376,7 @@ int live_rps_control(void *arg)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 	struct igt_spinner spin;
+	intel_wakeref_t wakeref;
 	int err = 0;
 
 	/*
@@ -397,7 +399,7 @@ int live_rps_control(void *arg)
 	saved_work = rps->work.func;
 	rps->work.func = dummy_rps_work;
 
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	for_each_engine(engine, gt, id) {
 		struct i915_request *rq;
 		ktime_t min_dt, max_dt;
@@ -487,7 +489,7 @@ int live_rps_control(void *arg)
 			break;
 		}
 	}
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 
 	igt_spinner_fini(&spin);
 
@@ -1022,6 +1024,7 @@ int live_rps_interrupt(void *arg)
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
 	struct igt_spinner spin;
+	intel_wakeref_t wakeref;
 	u32 pm_events;
 	int err = 0;
 
@@ -1032,9 +1035,9 @@ int live_rps_interrupt(void *arg)
 	if (!intel_rps_has_interrupts(rps) || GRAPHICS_VER(gt->i915) < 6)
 		return 0;
 
-	intel_gt_pm_get(gt);
-	pm_events = rps->pm_events;
-	intel_gt_pm_put(gt);
+	pm_events = 0;
+	with_intel_gt_pm(gt, wakeref)
+		pm_events = rps->pm_events;
 	if (!pm_events) {
 		pr_err("No RPS PM events registered, but RPS is enabled?\n");
 		return -ENODEV;
diff --git a/drivers/gpu/drm/i915/gt/selftest_slpc.c b/drivers/gpu/drm/i915/gt/selftest_slpc.c
index bd44ce73a5044e..81fa891eac19fc 100644
--- a/drivers/gpu/drm/i915/gt/selftest_slpc.c
+++ b/drivers/gpu/drm/i915/gt/selftest_slpc.c
@@ -241,6 +241,7 @@ static int run_test(struct intel_gt *gt, int test_type)
 	struct intel_rps *rps = &gt->rps;
 	struct intel_engine_cs *engine;
 	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
 	struct igt_spinner spin;
 	u32 slpc_min_freq, slpc_max_freq;
 	int err = 0;
@@ -278,7 +279,7 @@ static int run_test(struct intel_gt *gt, int test_type)
 	}
 
 	intel_gt_pm_wait_for_idle(gt);
-	intel_gt_pm_get(gt);
+	wakeref = intel_gt_pm_get(gt);
 	for_each_engine(engine, gt, id) {
 		struct i915_request *rq;
 		u32 max_act_freq;
@@ -365,7 +366,7 @@ static int run_test(struct intel_gt *gt, int test_type)
 	if (igt_flush_test(gt->i915))
 		err = -EIO;
 
-	intel_gt_pm_put(gt);
+	intel_gt_pm_put(gt, wakeref);
 	igt_spinner_fini(&spin);
 	intel_gt_pm_wait_for_idle(gt);
 
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index be495e657d66bd..978820f8697059 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -1106,7 +1106,7 @@ static void scrub_guc_desc_for_outstanding_g2h(struct intel_guc *guc)
 			if (deregister)
 				guc_signal_context_fence(ce);
 			if (destroyed) {
-				intel_gt_pm_put_async(guc_to_gt(guc));
+				intel_gt_pm_put_async_untracked(guc_to_gt(guc));
 				release_guc_id(guc, ce);
 				__guc_context_destroy(ce);
 			}
@@ -1302,6 +1302,7 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now)
 	unsigned long flags;
 	u32 reset_count;
 	bool in_reset;
+	intel_wakeref_t wakeref;
 
 	spin_lock_irqsave(&guc->timestamp.lock, flags);
 
@@ -1324,7 +1325,7 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now)
 	 * start_gt_clk is derived from GuC state. To get a consistent
 	 * view of activity, we query the GuC state only if gt is awake.
 	 */
-	if (!in_reset && intel_gt_pm_get_if_awake(gt)) {
+	if (!in_reset && (wakeref = intel_gt_pm_get_if_awake(gt))) {
 		stats_saved = *stats;
 		gt_stamp_saved = guc->timestamp.gt_stamp;
 		/*
@@ -1333,7 +1334,7 @@ static ktime_t guc_engine_busyness(struct intel_engine_cs *engine, ktime_t *now)
 		 */
 		guc_update_engine_gt_clks(engine);
 		guc_update_pm_timestamp(guc, now);
-		intel_gt_pm_put_async(gt);
+		intel_gt_pm_put_async(gt, wakeref);
 		if (i915_reset_count(gpu_error) != reset_count) {
 			*stats = stats_saved;
 			guc->timestamp.gt_stamp = gt_stamp_saved;
@@ -4545,7 +4546,7 @@ int intel_guc_deregister_done_process_msg(struct intel_guc *guc,
 		intel_context_put(ce);
 	} else if (context_destroyed(ce)) {
 		/* Context has been destroyed */
-		intel_gt_pm_put_async(guc_to_gt(guc));
+		intel_gt_pm_put_async_untracked(guc_to_gt(guc));
 		release_guc_id(guc, ce);
 		__guc_context_destroy(ce);
 	}
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 52531ab28c5f55..737d45d11d9f1f 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -168,19 +168,19 @@ static u64 get_rc6(struct intel_gt *gt)
 {
 	struct drm_i915_private *i915 = gt->i915;
 	struct i915_pmu *pmu = &i915->pmu;
+	intel_wakeref_t wakeref;
 	unsigned long flags;
-	bool awake = false;
 	u64 val;
 
-	if (intel_gt_pm_get_if_awake(gt)) {
+	wakeref = intel_gt_pm_get_if_awake(gt);
+	if (wakeref) {
 		val = __get_rc6(gt);
-		intel_gt_pm_put_async(gt);
-		awake = true;
+		intel_gt_pm_put_async(gt, wakeref);
 	}
 
 	spin_lock_irqsave(&pmu->lock, flags);
 
-	if (awake) {
+	if (wakeref) {
 		pmu->sample[__I915_SAMPLE_RC6].cur = val;
 	} else {
 		/*
@@ -373,12 +373,14 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns)
 	struct drm_i915_private *i915 = gt->i915;
 	struct i915_pmu *pmu = &i915->pmu;
 	struct intel_rps *rps = &gt->rps;
+	intel_wakeref_t wakeref;
 
 	if (!frequency_sampling_enabled(pmu))
 		return;
 
 	/* Report 0/0 (actual/requested) frequency while parked. */
-	if (!intel_gt_pm_get_if_awake(gt))
+	wakeref = intel_gt_pm_get_if_awake(gt);
+	if (!wakeref)
 		return;
 
 	if (pmu->enable & config_mask(I915_PMU_ACTUAL_FREQUENCY)) {
@@ -409,7 +411,7 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns)
 				period_ns / 1000);
 	}
 
-	intel_gt_pm_put_async(gt);
+	intel_gt_pm_put_async(gt, wakeref);
 }
 
 static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
index dfd87d08221807..db4887e33ea607 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.c
+++ b/drivers/gpu/drm/i915/intel_wakeref.c
@@ -108,6 +108,10 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
 	INIT_DELAYED_WORK(&wf->work, __intel_wakeref_put_work);
 	lockdep_init_map(&wf->work.work.lockdep_map,
 			 "wakeref.work", &key->work, 0);
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
+	intel_wakeref_tracker_init(&wf->debug);
+#endif
 }
 
 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index 20720fbcc28d46..f2de4ccb7f5377 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -43,6 +43,10 @@ struct intel_wakeref {
 	const struct intel_wakeref_ops *ops;
 
 	struct delayed_work work;
+
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
+	struct intel_wakeref_tracker debug;
+#endif
 };
 
 struct intel_wakeref_lockclass {
@@ -261,6 +265,44 @@ __intel_wakeref_defer_park(struct intel_wakeref *wf)
  */
 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
 
+#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
+
+static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
+{
+	return intel_wakeref_tracker_add(&wf->debug);
+}
+
+static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
+					 intel_wakeref_t handle)
+{
+	intel_wakeref_tracker_remove(&wf->debug, handle);
+}
+
+static inline void intel_wakeref_show(struct intel_wakeref *wf,
+				      struct drm_printer *p)
+{
+	intel_wakeref_tracker_show(&wf->debug, p);
+}
+
+#else
+
+static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
+{
+	return -1;
+}
+
+static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
+					 intel_wakeref_t handle)
+{
+}
+
+static inline void intel_wakeref_show(struct intel_wakeref *wf,
+				      struct drm_printer *p)
+{
+}
+
+#endif
+
 struct intel_wakeref_auto {
 	struct intel_runtime_pm *rpm;
 	struct timer_list timer;

-- 
2.34.1

[PATCH v4 08/10] drm/i915: Correct type of wakeref variable

[Andrzej Hajda]

Wakeref has dedicated type. Assumption it will be int
compatible forever is incorrect.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index 978820f8697059..c35f551193c9ad 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -3235,7 +3235,7 @@ static void destroyed_worker_func(struct work_struct *w)
 	struct intel_guc *guc = container_of(w, struct intel_guc,
 					     submission_state.destroyed_worker);
 	struct intel_gt *gt = guc_to_gt(guc);
-	int tmp;
+	intel_wakeref_t tmp;
 
 	with_intel_gt_pm(gt, tmp)
 		deregister_destroyed_contexts(guc);

-- 
2.34.1

[PATCH v4 09/10] drm/i915: replace Intel internal tracker with kernel core ref_tracker

[Andrzej Hajda]

Beside reusing existing code, the main advantage of ref_tracker is
tracking per instance of wakeref. It allows also to catch double
put.
On the other side we lose information about the first acquire and
the last release, but the advantages outweigh it.

v2: Call ref_tracker_dir_exit() only at driver shutdown not during
    suspend so add intel_runtime_pm_driver_last_release (Nirmoy)

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/Kconfig.debug                 |  11 +-
 drivers/gpu/drm/i915/Makefile                      |   3 -
 drivers/gpu/drm/i915/display/intel_display_power.c |   2 +-
 drivers/gpu/drm/i915/gt/intel_engine_pm.c          |   2 +-
 drivers/gpu/drm/i915/gt/intel_gt_pm.c              |   2 +-
 drivers/gpu/drm/i915/i915_driver.c                 |   2 +-
 drivers/gpu/drm/i915/intel_runtime_pm.c            |  27 ++-
 drivers/gpu/drm/i915/intel_runtime_pm.h            |   3 +-
 drivers/gpu/drm/i915/intel_wakeref.c               |   5 +-
 drivers/gpu/drm/i915/intel_wakeref.h               |  72 ++++++-
 drivers/gpu/drm/i915/intel_wakeref_tracker.c       | 234 ---------------------
 drivers/gpu/drm/i915/intel_wakeref_tracker.h       |  76 -------
 12 files changed, 89 insertions(+), 350 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index 63b77dc48d4394..d26fb4569873ea 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -24,6 +24,7 @@ config DRM_I915_DEBUG
 	select DEBUG_FS
 	select PREEMPT_COUNT
 	select I2C_CHARDEV
+	select REF_TRACKER
 	select STACKDEPOT
 	select STACKTRACE
 	select DRM_DP_AUX_CHARDEV
@@ -38,7 +39,6 @@ config DRM_I915_DEBUG
 	select DRM_I915_DEBUG_GEM
 	select DRM_I915_DEBUG_GEM_ONCE
 	select DRM_I915_DEBUG_MMIO
-	select DRM_I915_TRACK_WAKEREF
 	select DRM_I915_DEBUG_RUNTIME_PM
 	select DRM_I915_DEBUG_WAKEREF
 	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
@@ -230,18 +230,13 @@ config DRM_I915_DEBUG_VBLANK_EVADE
 
 	  If in doubt, say "N".
 
-config DRM_I915_TRACK_WAKEREF
-	depends on STACKDEPOT
-	depends on STACKTRACE
-	bool
-
 config DRM_I915_DEBUG_RUNTIME_PM
 	bool "Enable extra state checking for runtime PM"
 	depends on DRM_I915
 	default n
+	select REF_TRACKER
 	select STACKDEPOT
 	select STACKTRACE
-	select DRM_I915_TRACK_WAKEREF
 	help
 	  Choose this option to turn on extra state checking for the
 	  runtime PM functionality. This may introduce overhead during
@@ -255,9 +250,9 @@ config DRM_I915_DEBUG_WAKEREF
 	bool "Enable extra tracking for wakerefs"
 	depends on DRM_I915
 	default n
+	select REF_TRACKER
 	select STACKDEPOT
 	select STACKTRACE
-	select DRM_I915_TRACK_WAKEREF
 	help
 	  Choose this option to turn on extra state checking and usage
 	  tracking for the wakerefPM functionality. This may introduce
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 42daff6d575a82..8d64846430f8aa 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -82,9 +82,6 @@ i915-$(CONFIG_DEBUG_FS) += \
 	display/intel_display_debugfs.o \
 	display/intel_pipe_crc.o
 
-i915-$(CONFIG_DRM_I915_TRACK_WAKEREF) += \
-	intel_wakeref_tracker.o
-
 i915-$(CONFIG_PERF_EVENTS) += i915_pmu.o
 
 # "Graphics Technology" (aka we talk to the gpu)
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 743b919bb2cfd7..56c0a443f45c75 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -403,7 +403,7 @@ print_async_put_domains_state(struct i915_power_domains *power_domains)
 						     struct drm_i915_private,
 						     display.power.domains);
 
-	drm_dbg(&i915->drm, "async_put_wakeref %u\n",
+	drm_dbg(&i915->drm, "async_put_wakeref %lu\n",
 		power_domains->async_put_wakeref);
 
 	print_power_domains(power_domains, "async_put_domains[0]",
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index 7db9229d28639c..7063dea2112943 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -289,7 +289,7 @@ void intel_engine_init__pm(struct intel_engine_cs *engine)
 {
 	struct intel_runtime_pm *rpm = engine->uncore->rpm;
 
-	intel_wakeref_init(&engine->wakeref, rpm, &wf_ops);
+	intel_wakeref_init(&engine->wakeref, rpm, &wf_ops, engine->name);
 	intel_engine_init_heartbeat(engine);
 
 	intel_gsc_idle_msg_enable(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index 302f908b37fb2e..7f92aa02b2a013 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -166,7 +166,7 @@ void intel_gt_pm_init_early(struct intel_gt *gt)
 	 * runtime_pm is per-device rather than per-tile, so this is still the
 	 * correct structure.
 	 */
-	intel_wakeref_init(&gt->wakeref, &gt->i915->runtime_pm, &wf_ops);
+	intel_wakeref_init(&gt->wakeref, &gt->i915->runtime_pm, &wf_ops, "GT");
 	seqcount_mutex_init(&gt->stats.lock, &gt->wakeref.mutex);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index e3244972521cb1..e971670f4a0e98 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -1017,7 +1017,7 @@ void i915_driver_shutdown(struct drm_i915_private *i915)
 	intel_power_domains_driver_remove(i915);
 	enable_rpm_wakeref_asserts(&i915->runtime_pm);
 
-	intel_runtime_pm_driver_release(&i915->runtime_pm);
+	intel_runtime_pm_driver_last_release(&i915->runtime_pm);
 }
 
 static bool suspend_to_idle(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 43149cf12dc864..7e05098e5d3276 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -54,7 +54,7 @@
 
 static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
-	intel_wakeref_tracker_init(&rpm->debug);
+	ref_tracker_dir_init(&rpm->debug, INTEL_REFTRACK_DEAD_COUNT, dev_name(rpm->kdev));
 }
 
 static intel_wakeref_t
@@ -63,26 +63,26 @@ track_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 	if (!rpm->available || rpm->no_wakeref_tracking)
 		return -1;
 
-	return intel_wakeref_tracker_add(&rpm->debug);
+	return intel_ref_tracker_alloc(&rpm->debug);
 }
 
 static void untrack_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
 					     intel_wakeref_t wakeref)
 {
-	intel_wakeref_tracker_remove(&rpm->debug, wakeref);
+	if (!rpm->available || rpm->no_wakeref_tracking)
+		return;
+
+	intel_ref_tracker_free(&rpm->debug, wakeref);
 }
 
 static void untrack_all_intel_runtime_pm_wakerefs(struct intel_runtime_pm *rpm)
 {
-	struct drm_printer p = drm_debug_printer("i915");
-
-	intel_wakeref_tracker_reset(&rpm->debug, &p);
+	ref_tracker_dir_exit(&rpm->debug);
 }
 
 static noinline void
 __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 {
-	struct intel_wakeref_tracker saved;
 	unsigned long flags;
 
 	if (!atomic_dec_and_lock_irqsave(&rpm->wakeref_count,
@@ -90,15 +90,8 @@ __intel_wakeref_dec_and_check_tracking(struct intel_runtime_pm *rpm)
 					 flags))
 		return;
 
-	saved = __intel_wakeref_tracker_reset(&rpm->debug);
+	__ref_tracker_dir_print(&rpm->debug, INTEL_REFTRACK_PRINT_LIMIT);
 	spin_unlock_irqrestore(&rpm->debug.lock, flags);
-
-	if (saved.count) {
-		struct drm_printer p = drm_debug_printer("i915");
-
-		__intel_wakeref_tracker_show(&saved, &p);
-		intel_wakeref_tracker_fini(&saved);
-	}
 }
 
 void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
@@ -455,7 +448,11 @@ void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm)
 		 "i915 raw-wakerefs=%d wakelocks=%d on cleanup\n",
 		 intel_rpm_raw_wakeref_count(count),
 		 intel_rpm_wakelock_count(count));
+}
 
+void intel_runtime_pm_driver_last_release(struct intel_runtime_pm *rpm)
+{
+	intel_runtime_pm_driver_release(rpm);
 	untrack_all_intel_runtime_pm_wakerefs(rpm);
 }
 
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.h b/drivers/gpu/drm/i915/intel_runtime_pm.h
index a8dc2baf79844f..2f81d685bdb4d1 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.h
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.h
@@ -83,7 +83,7 @@ struct intel_runtime_pm {
 	 * paired rpm_put) we can remove corresponding pairs of and keep
 	 * the array trimmed to active wakerefs.
 	 */
-	struct intel_wakeref_tracker debug;
+	struct ref_tracker_dir debug;
 #endif
 };
 
@@ -187,6 +187,7 @@ void intel_runtime_pm_init_early(struct intel_runtime_pm *rpm);
 void intel_runtime_pm_enable(struct intel_runtime_pm *rpm);
 void intel_runtime_pm_disable(struct intel_runtime_pm *rpm);
 void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm);
+void intel_runtime_pm_driver_last_release(struct intel_runtime_pm *rpm);
 
 intel_wakeref_t intel_runtime_pm_get(struct intel_runtime_pm *rpm);
 intel_wakeref_t intel_runtime_pm_get_if_in_use(struct intel_runtime_pm *rpm);
diff --git a/drivers/gpu/drm/i915/intel_wakeref.c b/drivers/gpu/drm/i915/intel_wakeref.c
index db4887e33ea607..61f974d97a3757 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.c
+++ b/drivers/gpu/drm/i915/intel_wakeref.c
@@ -96,7 +96,8 @@ static void __intel_wakeref_put_work(struct work_struct *wrk)
 void __intel_wakeref_init(struct intel_wakeref *wf,
 			  struct intel_runtime_pm *rpm,
 			  const struct intel_wakeref_ops *ops,
-			  struct intel_wakeref_lockclass *key)
+			  struct intel_wakeref_lockclass *key,
+			  const char *name)
 {
 	wf->rpm = rpm;
 	wf->ops = ops;
@@ -110,7 +111,7 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
 			 "wakeref.work", &key->work, 0);
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
-	intel_wakeref_tracker_init(&wf->debug);
+	ref_tracker_dir_init(&wf->debug, INTEL_REFTRACK_DEAD_COUNT, name);
 #endif
 }
 
diff --git a/drivers/gpu/drm/i915/intel_wakeref.h b/drivers/gpu/drm/i915/intel_wakeref.h
index f2de4ccb7f5377..cf6828f13943d7 100644
--- a/drivers/gpu/drm/i915/intel_wakeref.h
+++ b/drivers/gpu/drm/i915/intel_wakeref.h
@@ -7,17 +7,24 @@
 #ifndef INTEL_WAKEREF_H
 #define INTEL_WAKEREF_H
 
+#include <drm/drm_print.h>
+
 #include <linux/atomic.h>
 #include <linux/bitfield.h>
 #include <linux/bits.h>
 #include <linux/lockdep.h>
 #include <linux/mutex.h>
 #include <linux/refcount.h>
+#include <linux/ref_tracker.h>
+#include <linux/slab.h>
 #include <linux/stackdepot.h>
 #include <linux/timer.h>
 #include <linux/workqueue.h>
 
-#include "intel_wakeref_tracker.h"
+typedef unsigned long intel_wakeref_t;
+
+#define INTEL_REFTRACK_DEAD_COUNT 16
+#define INTEL_REFTRACK_PRINT_LIMIT 16
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 #define INTEL_WAKEREF_BUG_ON(expr) BUG_ON(expr)
@@ -45,7 +52,7 @@ struct intel_wakeref {
 	struct delayed_work work;
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
-	struct intel_wakeref_tracker debug;
+	struct ref_tracker_dir debug;
 #endif
 };
 
@@ -57,11 +64,12 @@ struct intel_wakeref_lockclass {
 void __intel_wakeref_init(struct intel_wakeref *wf,
 			  struct intel_runtime_pm *rpm,
 			  const struct intel_wakeref_ops *ops,
-			  struct intel_wakeref_lockclass *key);
-#define intel_wakeref_init(wf, rpm, ops) do {				\
+			  struct intel_wakeref_lockclass *key,
+			  const char *name);
+#define intel_wakeref_init(wf, rpm, ops, name) do {				\
 	static struct intel_wakeref_lockclass __key;			\
 									\
-	__intel_wakeref_init((wf), (rpm), (ops), &__key);		\
+	__intel_wakeref_init((wf), (rpm), (ops), &__key, name);		\
 } while (0)
 
 int __intel_wakeref_get_first(struct intel_wakeref *wf);
@@ -265,17 +273,67 @@ __intel_wakeref_defer_park(struct intel_wakeref *wf)
  */
 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf);
 
+#define INTEL_WAKEREF_DEF ((intel_wakeref_t)(-1))
+
+static inline intel_wakeref_t intel_ref_tracker_alloc(struct ref_tracker_dir *dir)
+{
+	struct ref_tracker *user = NULL;
+
+	ref_tracker_alloc(dir, &user, GFP_NOWAIT);
+
+	return (intel_wakeref_t)user ?: INTEL_WAKEREF_DEF;
+}
+
+static inline void intel_ref_tracker_free(struct ref_tracker_dir *dir,
+					  intel_wakeref_t handle)
+{
+	struct ref_tracker *user;
+
+	user = (handle == INTEL_WAKEREF_DEF) ? NULL : (void *)handle;
+
+	ref_tracker_free(dir, &user);
+}
+
+static inline void
+intel_wakeref_tracker_show(struct ref_tracker_dir *dir,
+			   struct drm_printer *p)
+{
+	const size_t buf_size = PAGE_SIZE;
+	char *buf, *sb, *se;
+	size_t count;
+
+	buf = kmalloc(buf_size, GFP_NOWAIT);
+	if (!buf)
+		return;
+
+	count = ref_tracker_dir_snprint(dir, buf, buf_size);
+	if (!count)
+		goto free;
+	/* printk does not like big buffers, so we split it */
+	for (sb = buf; *sb; sb = se + 1) {
+		se = strchrnul(sb, '\n');
+		drm_printf(p, "%.*s", (int)(se - sb + 1), sb);
+		if (!*se)
+			break;
+	}
+	if (count >= buf_size)
+		drm_printf(p, "\n...dropped %zd extra bytes of leak report.\n",
+			   count + 1 - buf_size);
+free:
+	kfree(buf);
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 
 static inline intel_wakeref_t intel_wakeref_track(struct intel_wakeref *wf)
 {
-	return intel_wakeref_tracker_add(&wf->debug);
+	return intel_ref_tracker_alloc(&wf->debug);
 }
 
 static inline void intel_wakeref_untrack(struct intel_wakeref *wf,
 					 intel_wakeref_t handle)
 {
-	intel_wakeref_tracker_remove(&wf->debug, handle);
+	intel_ref_tracker_free(&wf->debug, handle);
 }
 
 static inline void intel_wakeref_show(struct intel_wakeref *wf,
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.c b/drivers/gpu/drm/i915/intel_wakeref_tracker.c
deleted file mode 100644
index c92035030a75cc..00000000000000
--- a/drivers/gpu/drm/i915/intel_wakeref_tracker.c
+++ /dev/null
@@ -1,234 +0,0 @@
-// SPDX-License-Identifier: MIT
-/*
- * Copyright © 2021 Intel Corporation
- */
-
-#include <linux/slab.h>
-#include <linux/stackdepot.h>
-#include <linux/stacktrace.h>
-#include <linux/sort.h>
-
-#include <drm/drm_print.h>
-
-#include "intel_wakeref_tracker.h"
-
-#define STACKDEPTH 8
-
-static noinline depot_stack_handle_t __save_depot_stack(void)
-{
-	unsigned long entries[STACKDEPTH];
-	unsigned int n;
-
-	n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
-	return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
-}
-
-static void __print_depot_stack(depot_stack_handle_t stack,
-				char *buf, int sz, int indent)
-{
-	unsigned long *entries;
-	unsigned int nr_entries;
-
-	nr_entries = stack_depot_fetch(stack, &entries);
-	stack_trace_snprint(buf, sz, entries, nr_entries, indent);
-}
-
-static int cmphandle(const void *_a, const void *_b)
-{
-	const depot_stack_handle_t * const a = _a, * const b = _b;
-
-	if (*a < *b)
-		return -1;
-	else if (*a > *b)
-		return 1;
-	else
-		return 0;
-}
-
-void
-__intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
-			     struct drm_printer *p)
-{
-	unsigned long i;
-	char *buf;
-
-	buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-	if (!buf)
-		return;
-
-	if (w->last_acquire) {
-		__print_depot_stack(w->last_acquire, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last acquired:\n%s", buf);
-	}
-
-	if (w->last_release) {
-		__print_depot_stack(w->last_release, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref last released:\n%s", buf);
-	}
-
-	drm_printf(p, "Wakeref count: %lu\n", w->count);
-
-	sort(w->owners, w->count, sizeof(*w->owners), cmphandle, NULL);
-
-	for (i = 0; i < w->count; i++) {
-		depot_stack_handle_t stack = w->owners[i];
-		unsigned long rep;
-
-		rep = 1;
-		while (i + 1 < w->count && w->owners[i + 1] == stack)
-			rep++, i++;
-		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
-		drm_printf(p, "Wakeref x%lu taken at:\n%s", rep, buf);
-	}
-
-	kfree(buf);
-}
-
-void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
-				struct drm_printer *p)
-{
-	struct intel_wakeref_tracker tmp = {};
-
-	do {
-		unsigned long alloc = tmp.count;
-		depot_stack_handle_t *s;
-
-		spin_lock_irq(&w->lock);
-		tmp.count = w->count;
-		if (tmp.count <= alloc)
-			memcpy(tmp.owners, w->owners, tmp.count * sizeof(*s));
-		tmp.last_acquire = w->last_acquire;
-		tmp.last_release = w->last_release;
-		spin_unlock_irq(&w->lock);
-		if (tmp.count <= alloc)
-			break;
-
-		s = krealloc(tmp.owners,
-			     tmp.count * sizeof(*s),
-			     GFP_NOWAIT | __GFP_NOWARN);
-		if (!s)
-			goto out;
-
-		tmp.owners = s;
-	} while (1);
-
-	__intel_wakeref_tracker_show(&tmp, p);
-
-out:
-	intel_wakeref_tracker_fini(&tmp);
-}
-
-intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
-{
-	depot_stack_handle_t stack, *stacks;
-	unsigned long flags;
-
-	stack = __save_depot_stack();
-	if (!stack)
-		return -1;
-
-	spin_lock_irqsave(&w->lock, flags);
-
-	if (!w->count)
-		w->last_acquire = stack;
-
-	stacks = krealloc(w->owners,
-			  (w->count + 1) * sizeof(*stacks),
-			  GFP_NOWAIT | __GFP_NOWARN);
-	if (stacks) {
-		stacks[w->count++] = stack;
-		w->owners = stacks;
-	} else {
-		stack = -1;
-	}
-
-	spin_unlock_irqrestore(&w->lock, flags);
-
-	return stack;
-}
-
-void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
-				  intel_wakeref_t stack)
-{
-	unsigned long flags, n;
-	bool found = false;
-
-	if (unlikely(stack == -1))
-		return;
-
-	spin_lock_irqsave(&w->lock, flags);
-	for (n = w->count; n--; ) {
-		if (w->owners[n] == stack) {
-			memmove(w->owners + n,
-				w->owners + n + 1,
-				(--w->count - n) * sizeof(stack));
-			found = true;
-			break;
-		}
-	}
-	spin_unlock_irqrestore(&w->lock, flags);
-
-	if (WARN(!found,
-		 "Unmatched wakeref %x, tracking %lu\n",
-		 stack, w->count)) {
-		char *buf;
-
-		buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
-		if (!buf)
-			return;
-
-		__print_depot_stack(stack, buf, PAGE_SIZE, 2);
-		pr_err("wakeref %x from\n%s", stack, buf);
-
-		stack = READ_ONCE(w->last_release);
-		if (stack && !w->count) {
-			__print_depot_stack(stack, buf, PAGE_SIZE, 2);
-			pr_err("wakeref last released at\n%s", buf);
-		}
-
-		kfree(buf);
-	}
-}
-
-struct intel_wakeref_tracker
-__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
-{
-	struct intel_wakeref_tracker saved;
-
-	lockdep_assert_held(&w->lock);
-
-	saved = *w;
-
-	w->owners = NULL;
-	w->count = 0;
-	w->last_release = __save_depot_stack();
-
-	return saved;
-}
-
-void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
-				 struct drm_printer *p)
-{
-	struct intel_wakeref_tracker tmp;
-
-	spin_lock_irq(&w->lock);
-	tmp = __intel_wakeref_tracker_reset(w);
-	spin_unlock_irq(&w->lock);
-
-	if (tmp.count)
-		__intel_wakeref_tracker_show(&tmp, p);
-
-	intel_wakeref_tracker_fini(&tmp);
-}
-
-void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w)
-{
-	memset(w, 0, sizeof(*w));
-	spin_lock_init(&w->lock);
-	stack_depot_init();
-}
-
-void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w)
-{
-	kfree(w->owners);
-}
diff --git a/drivers/gpu/drm/i915/intel_wakeref_tracker.h b/drivers/gpu/drm/i915/intel_wakeref_tracker.h
deleted file mode 100644
index 61df68e28c0fbf..00000000000000
--- a/drivers/gpu/drm/i915/intel_wakeref_tracker.h
+++ /dev/null
@@ -1,76 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-/*
- * Copyright © 2019 Intel Corporation
- */
-
-#ifndef INTEL_WAKEREF_TRACKER_H
-#define INTEL_WAKEREF_TRACKER_H
-
-#include <linux/kconfig.h>
-#include <linux/spinlock.h>
-#include <linux/stackdepot.h>
-
-typedef depot_stack_handle_t intel_wakeref_t;
-
-struct drm_printer;
-
-struct intel_wakeref_tracker {
-	spinlock_t lock;
-
-	depot_stack_handle_t last_acquire;
-	depot_stack_handle_t last_release;
-
-	depot_stack_handle_t *owners;
-	unsigned long count;
-};
-
-#if IS_ENABLED(CONFIG_DRM_I915_TRACK_WAKEREF)
-
-void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w);
-void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w);
-
-intel_wakeref_t intel_wakeref_tracker_add(struct intel_wakeref_tracker *w);
-void intel_wakeref_tracker_remove(struct intel_wakeref_tracker *w,
-			   intel_wakeref_t handle);
-
-struct intel_wakeref_tracker
-__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w);
-void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
-				 struct drm_printer *p);
-
-void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w,
-				  struct drm_printer *p);
-void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w,
-				struct drm_printer *p);
-
-#else
-
-static inline void intel_wakeref_tracker_init(struct intel_wakeref_tracker *w) {}
-static inline void intel_wakeref_tracker_fini(struct intel_wakeref_tracker *w) {}
-
-static inline intel_wakeref_t
-intel_wakeref_tracker_add(struct intel_wakeref_tracker *w)
-{
-	return -1;
-}
-
-static inline void
-intel_wakeref_untrack_remove(struct intel_wakeref_tracker *w, intel_wakeref_t handle) {}
-
-static inline struct intel_wakeref_tracker
-__intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w)
-{
-	return (struct intel_wakeref_tracker){};
-}
-
-static inline void intel_wakeref_tracker_reset(struct intel_wakeref_tracker *w,
-					       struct drm_printer *p)
-{
-}
-
-static inline void __intel_wakeref_tracker_show(const struct intel_wakeref_tracker *w, struct drm_printer *p) {}
-static inline void intel_wakeref_tracker_show(struct intel_wakeref_tracker *w, struct drm_printer *p) {}
-
-#endif
-
-#endif /* INTEL_WAKEREF_TRACKER_H */

-- 
2.34.1

[PATCH v4 10/10] drm/i915/gt: Hold a wakeref for the active VM

[Andrzej Hajda]

From: Chris Wilson <chris@chris-wilson.co.uk>

There may be a disconnect between the GT used by the engine and the GT
used for the VM, requiring us to hold a wakeref on both while the GPU is
active with this request.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/i915/gt/intel_context.h       | 15 +++++++++++----
 drivers/gpu/drm/i915/gt/intel_context_types.h |  2 ++
 drivers/gpu/drm/i915/gt/intel_engine_pm.c     |  4 ++++
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index 0a8d553da3f439..582faa21181e58 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -14,6 +14,7 @@
 #include "i915_drv.h"
 #include "intel_context_types.h"
 #include "intel_engine_types.h"
+#include "intel_gt_pm.h"
 #include "intel_ring_types.h"
 #include "intel_timeline_types.h"
 #include "i915_trace.h"
@@ -207,8 +208,11 @@ void intel_context_exit_engine(struct intel_context *ce);
 static inline void intel_context_enter(struct intel_context *ce)
 {
 	lockdep_assert_held(&ce->timeline->mutex);
-	if (!ce->active_count++)
-		ce->ops->enter(ce);
+	if (ce->active_count++)
+		return;
+
+	ce->ops->enter(ce);
+	ce->wakeref = intel_gt_pm_get(ce->vm->gt);
 }
 
 static inline void intel_context_mark_active(struct intel_context *ce)
@@ -222,8 +226,11 @@ static inline void intel_context_exit(struct intel_context *ce)
 {
 	lockdep_assert_held(&ce->timeline->mutex);
 	GEM_BUG_ON(!ce->active_count);
-	if (!--ce->active_count)
-		ce->ops->exit(ce);
+	if (--ce->active_count)
+		return;
+
+	intel_gt_pm_put_async(ce->vm->gt, ce->wakeref);
+	ce->ops->exit(ce);
 }
 
 static inline struct intel_context *intel_context_get(struct intel_context *ce)
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index e36670f2e6260b..5dc39a9d7a501c 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -17,6 +17,7 @@
 #include "i915_utils.h"
 #include "intel_engine_types.h"
 #include "intel_sseu.h"
+#include "intel_wakeref.h"
 
 #include "uc/intel_guc_fwif.h"
 
@@ -110,6 +111,7 @@ struct intel_context {
 	u32 ring_size;
 	struct intel_ring *ring;
 	struct intel_timeline *timeline;
+	intel_wakeref_t wakeref;
 
 	unsigned long flags;
 #define CONTEXT_BARRIER_BIT		0
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index 7063dea2112943..c2d17c97bfe989 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -114,6 +114,10 @@ __queue_and_release_pm(struct i915_request *rq,
 
 	ENGINE_TRACE(engine, "parking\n");
 
+	GEM_BUG_ON(rq->context->active_count != 1);
+	__intel_gt_pm_get(engine->gt);
+	rq->context->wakeref = intel_wakeref_track(&engine->gt->wakeref);
+
 	/*
 	 * We have to serialise all potential retirement paths with our
 	 * submission, as we don't want to underflow either the

-- 
2.34.1

Re: [Intel-gfx] [PATCH v4 00/10] drm/i915: use ref_tracker library for tracking wakerefs

[Andrzej Hajda]

Hi all,

Gently ping on the series.

Regards
Andrzej

On 06.03.2023 17:31, Andrzej Hajda wrote:
> This is revived patchset improving ref_tracker library and converting
> i915 internal tracker to ref_tracker.
> The old thread ended without consensus about small kernel allocations,
> which are performed under spinlock.
> I have tried to solve the problem by splitting the calls, but it results
> in complicated API, so I went back to original solution.
> If there are better solutions I am glad to discuss them.
> Meanwhile I send original patchset with addressed remaining comments.
> 
> To: Jani Nikula <jani.nikula@linux.intel.com>
> To: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> To: Rodrigo Vivi <rodrigo.vivi@intel.com>
> To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> To: David Airlie <airlied@gmail.com>
> To: Daniel Vetter <daniel@ffwll.ch>
> Cc: linux-kernel@vger.kernel.org
> Cc: intel-gfx@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: netdev@vger.kernel.org
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
> 
> ---
> Changes in v4:
> - split "Separate wakeref tracking" to smaller parts
> - fixed typos,
> - Link to v1-v3: https://patchwork.freedesktop.org/series/100327/
> 
> ---
> Andrzej Hajda (7):
>        lib/ref_tracker: add unlocked leak print helper
>        lib/ref_tracker: __ref_tracker_dir_print improve printing
>        lib/ref_tracker: add printing to memory buffer
>        lib/ref_tracker: remove warnings in case of allocation failure
>        drm/i915: Separate wakeref tracking types from rpm
>        drm/i915: Correct type of wakeref variable
>        drm/i915: replace Intel internal tracker with kernel core ref_tracker
> 
> Chris Wilson (3):
>        drm/i915: Separate wakeref tracking
>        drm/i915: Track leaked gt->wakerefs
>        drm/i915/gt: Hold a wakeref for the active VM
> 
>   drivers/gpu/drm/i915/Kconfig.debug                 |  19 ++
>   drivers/gpu/drm/i915/Makefile                      |   1 +
>   drivers/gpu/drm/i915/display/intel_display_power.c |   2 +-
>   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c     |   7 +-
>   .../drm/i915/gem/selftests/i915_gem_coherency.c    |  10 +-
>   drivers/gpu/drm/i915/gem/selftests/i915_gem_mman.c |  14 +-
>   drivers/gpu/drm/i915/gt/intel_breadcrumbs.c        |  13 +-
>   drivers/gpu/drm/i915/gt/intel_breadcrumbs_types.h  |   3 +-
>   drivers/gpu/drm/i915/gt/intel_context.h            |  15 +-
>   drivers/gpu/drm/i915/gt/intel_context_types.h      |   2 +
>   drivers/gpu/drm/i915/gt/intel_engine_pm.c          |  10 +-
>   drivers/gpu/drm/i915/gt/intel_engine_types.h       |   2 +
>   .../gpu/drm/i915/gt/intel_execlists_submission.c   |   2 +-
>   drivers/gpu/drm/i915/gt/intel_gt_pm.c              |  12 +-
>   drivers/gpu/drm/i915/gt/intel_gt_pm.h              |  38 +++-
>   drivers/gpu/drm/i915/gt/intel_gt_pm_debugfs.c      |   4 +-
>   drivers/gpu/drm/i915/gt/selftest_engine_cs.c       |  20 +-
>   drivers/gpu/drm/i915/gt/selftest_gt_pm.c           |   5 +-
>   drivers/gpu/drm/i915/gt/selftest_reset.c           |  10 +-
>   drivers/gpu/drm/i915/gt/selftest_rps.c             |  17 +-
>   drivers/gpu/drm/i915/gt/selftest_slpc.c            |   5 +-
>   drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c  |  11 +-
>   drivers/gpu/drm/i915/i915_driver.c                 |   2 +-
>   drivers/gpu/drm/i915/i915_pmu.c                    |  16 +-
>   drivers/gpu/drm/i915/intel_runtime_pm.c            | 221 ++-------------------
>   drivers/gpu/drm/i915/intel_runtime_pm.h            |  11 +-
>   drivers/gpu/drm/i915/intel_wakeref.c               |   7 +-
>   drivers/gpu/drm/i915/intel_wakeref.h               | 112 ++++++++++-
>   include/linux/ref_tracker.h                        |  31 ++-
>   lib/ref_tracker.c                                  | 179 ++++++++++++++---
>   30 files changed, 469 insertions(+), 332 deletions(-)
> ---
> base-commit: 1ddc2effff762c6a109af52f3c39534c7115aebe
> change-id: 20230224-track_gt-1b3da8bdacd7
> 
> Best regards,

Re: [Intel-gfx] [PATCH v4 01/10] lib/ref_tracker: add unlocked leak print helper

[Andi Shyti]

Hi Andrzej,

[...]

> diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
> index dc7b14aa3431e2..5e9f90bbf771b0 100644
> --- a/lib/ref_tracker.c
> +++ b/lib/ref_tracker.c
> @@ -14,6 +14,38 @@ struct ref_tracker {
>  	depot_stack_handle_t	free_stack_handle;
>  };
>  
> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
> +			   unsigned int display_limit)

can we call this ref_tracker_dir_print_locked() instead of using
the '__'?

> +{
> +	struct ref_tracker *tracker;
> +	unsigned int i = 0;
> +
> +	lockdep_assert_held(&dir->lock);
> +
> +	list_for_each_entry(tracker, &dir->list, head) {
> +		if (i < display_limit) {
> +			pr_err("leaked reference.\n");
> +			if (tracker->alloc_stack_handle)
> +				stack_depot_print(tracker->alloc_stack_handle);
> +			i++;
> +		} else {
> +			break;
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(__ref_tracker_dir_print);
> +
> +void ref_tracker_dir_print(struct ref_tracker_dir *dir,
> +			   unsigned int display_limit)
> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dir->lock, flags);
> +	__ref_tracker_dir_print(dir, display_limit);
> +	spin_unlock_irqrestore(&dir->lock, flags);
> +}
> +EXPORT_SYMBOL(ref_tracker_dir_print);
> +
>  void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>  {
>  	struct ref_tracker *tracker, *n;
> @@ -27,13 +59,13 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>  		kfree(tracker);
>  		dir->quarantine_avail++;
>  	}
> -	list_for_each_entry_safe(tracker, n, &dir->list, head) {
> -		pr_err("leaked reference.\n");
> -		if (tracker->alloc_stack_handle)
> -			stack_depot_print(tracker->alloc_stack_handle);
> +	if (!list_empty(&dir->list)) {
> +		__ref_tracker_dir_print(dir, 16);
>  		leak = true;
> -		list_del(&tracker->head);
> -		kfree(tracker);
> +		list_for_each_entry_safe(tracker, n, &dir->list, head) {
> +			list_del(&tracker->head);
> +			kfree(tracker);
> +		}

Just thinking whether this should go on a different patch, but I
don't have a strong opinion.

Looks good!

Andi

Re: [Intel-gfx] [PATCH v4 02/10] lib/ref_tracker: __ref_tracker_dir_print improve printing

[Andi Shyti]

Hi Andrzej,

looks good, few comments below,

On Mon, Mar 06, 2023 at 05:31:58PM +0100, Andrzej Hajda wrote:
> To improve readability of ref_tracker printing following changes
> have been performed:
> - reports are printed per stack_handle - log is more compact,
> - added display name for ref_tracker_dir,
> - stack trace is printed indented, in the same printk call,
> - total number of references is printed every time,
> - print info about dropped references.

nit: I think you can do better with the log :)

> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
> ---
>  include/linux/ref_tracker.h | 15 ++++++--
>  lib/ref_tracker.c           | 90 +++++++++++++++++++++++++++++++++++++++------
>  2 files changed, 91 insertions(+), 14 deletions(-)
> 
> diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
> index 3e9e9df2a41f5f..a2cf1f6309adb2 100644
> --- a/include/linux/ref_tracker.h
> +++ b/include/linux/ref_tracker.h
> @@ -17,12 +17,19 @@ struct ref_tracker_dir {
>  	bool			dead;
>  	struct list_head	list; /* List of active trackers */
>  	struct list_head	quarantine; /* List of dead trackers */
> +	char			name[32];
>  #endif
>  };
>  
>  #ifdef CONFIG_REF_TRACKER
> -static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
> -					unsigned int quarantine_count)
> +
> +// Temporary allow two and three arguments, until consumers are converted

I thought only Linus was allowed to use '//' :)

> +#define ref_tracker_dir_init(_d, _q, args...) _ref_tracker_dir_init(_d, _q, ##args, #_d)
> +#define _ref_tracker_dir_init(_d, _q, _n, ...) __ref_tracker_dir_init(_d, _q, _n)

[...]

> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
> +			   unsigned int display_limit)
> +{
> +	struct ref_tracker_dir_stats *stats;
> +	unsigned int i = 0, skipped;
> +	depot_stack_handle_t stack;
> +	char *sbuf;
> +
> +	lockdep_assert_held(&dir->lock);
> +
> +	if (list_empty(&dir->list))
> +		return;
> +
> +	stats = ref_tracker_get_stats(dir, display_limit);
> +	if (IS_ERR(stats)) {
> +		pr_err("%s@%pK: couldn't get stats, error %pe\n",
> +		       dir->name, dir, stats);
> +		return;
>  	}
> +
> +	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
> +
> +	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
> +		stack = stats->stacks[i].stack_handle;
> +		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
> +			sbuf[0] = 0;
> +		pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
> +		       stats->stacks[i].count, stats->total, sbuf);

what if sbuf is NULL?

> +		skipped -= stats->stacks[i].count;
> +	}
> +
> +	if (skipped)

is skipped used to double check whether stats->count is equal to
all the stacks[].conunts? What are the cases when skipped is > 0?

Andi

> +		pr_err("%s@%pK skipped reports about %d/%d users.\n",
> +		       dir->name, dir, skipped, stats->total);
> +
> +	kfree(sbuf);
> +
> +	kfree(stats);
>  }
>  EXPORT_SYMBOL(__ref_tracker_dir_print);
>  
> 
> -- 
> 2.34.1

Re: [Intel-gfx] [PATCH v4 03/10] lib/ref_tracker: add printing to memory buffer

[Andi Shyti]

Hi Andrzej,

This looks also good, just few questions.

On Mon, Mar 06, 2023 at 05:31:59PM +0100, Andrzej Hajda wrote:
> In case one wants to show stats via debugfs.

shall I say it? I'll say it... you can do better with the log
here. It's not a typo fix :)

> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>

[...]

> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
> +			   unsigned int display_limit)
> +{
> +	struct ostream os = {};
> +
> +	__ref_tracker_dir_pr_ostream(dir, display_limit, &os);
> +}
>  EXPORT_SYMBOL(__ref_tracker_dir_print);
>  
>  void ref_tracker_dir_print(struct ref_tracker_dir *dir,
> @@ -114,6 +141,19 @@ void ref_tracker_dir_print(struct ref_tracker_dir *dir,
>  }
>  EXPORT_SYMBOL(ref_tracker_dir_print);
>  
> +int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)

nit: snprintf is normally referred to its variable parameter
counterpart... I would choose a different name... how about
ref_tracker_dir_fetch_print()?

> +{
> +	struct ostream os = { .buf = buf, .size = size };
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dir->lock, flags);
> +	__ref_tracker_dir_pr_ostream(dir, 16, &os);
> +	spin_unlock_irqrestore(&dir->lock, flags);

What are you trying to protect with this spinlock? what if
the caller has already locked here? do we need a _locked()
version?

Thanks,
Andi

> +	return os.used;
> +}
> +EXPORT_SYMBOL(ref_tracker_dir_snprint);
> +
>  void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>  {
>  	struct ref_tracker *tracker, *n;
> 
> -- 
> 2.34.1

Re: [Intel-gfx] [PATCH v4 04/10] lib/ref_tracker: remove warnings in case of allocation failure

[Andi Shyti]

Hi Andrzej,

On Mon, Mar 06, 2023 at 05:32:00PM +0100, Andrzej Hajda wrote:
> Library can handle allocation failures. To avoid allocation warnings
> __GFP_NOWARN has been added everywhere. Moreover GFP_ATOMIC has been
> replaced with GFP_NOWAIT in case of stack allocation on tracker free
> call.
> 
> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>

Andi

Re: [Intel-gfx] [PATCH v4 06/10] drm/i915: Separate wakeref tracking

[Andi Shyti]

Hi Andrzej,

On Mon, Mar 06, 2023 at 05:32:02PM +0100, Andrzej Hajda wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Extract the callstack tracking of intel_runtime_pm.c into its own
> utility so that that we can reuse it for other online debugging of
> scoped wakerefs.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
> ---
>  drivers/gpu/drm/i915/Kconfig.debug           |   9 ++
>  drivers/gpu/drm/i915/Makefile                |   4 +
>  drivers/gpu/drm/i915/intel_runtime_pm.c      | 222 +++----------------------
>  drivers/gpu/drm/i915/intel_wakeref.h         |   2 +-
>  drivers/gpu/drm/i915/intel_wakeref_tracker.c | 234 +++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_wakeref_tracker.h |  52 ++++++
>  6 files changed, 319 insertions(+), 204 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index 93dfb7ed970547..5fde52107e3b44 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -25,6 +25,7 @@ config DRM_I915_DEBUG
>  	select PREEMPT_COUNT
>  	select I2C_CHARDEV
>  	select STACKDEPOT
> +	select STACKTRACE
>  	select DRM_DP_AUX_CHARDEV
>  	select X86_MSR # used by igt/pm_rpm
>  	select DRM_VGEM # used by igt/prime_vgem (dmabuf interop checks)
> @@ -37,6 +38,7 @@ config DRM_I915_DEBUG
>  	select DRM_I915_DEBUG_GEM
>  	select DRM_I915_DEBUG_GEM_ONCE
>  	select DRM_I915_DEBUG_MMIO
> +	select DRM_I915_TRACK_WAKEREF
>  	select DRM_I915_DEBUG_RUNTIME_PM
>  	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
>  	select DRM_I915_SELFTEST
> @@ -227,11 +229,18 @@ config DRM_I915_DEBUG_VBLANK_EVADE
>  
>  	  If in doubt, say "N".
>  
> +config DRM_I915_TRACK_WAKEREF
> +	depends on STACKDEPOT
> +	depends on STACKTRACE
> +	bool
> +
>  config DRM_I915_DEBUG_RUNTIME_PM
>  	bool "Enable extra state checking for runtime PM"
>  	depends on DRM_I915
>  	default n
>  	select STACKDEPOT
> +	select STACKTRACE
> +	select DRM_I915_TRACK_WAKEREF
>  	help
>  	  Choose this option to turn on extra state checking for the
>  	  runtime PM functionality. This may introduce overhead during
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index b2f91a1f826858..42daff6d575a82 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -81,6 +81,10 @@ i915-$(CONFIG_DEBUG_FS) += \
>  	i915_debugfs_params.o \
>  	display/intel_display_debugfs.o \
>  	display/intel_pipe_crc.o
> +
> +i915-$(CONFIG_DRM_I915_TRACK_WAKEREF) += \
> +	intel_wakeref_tracker.o
> +

This patch, along with the previous one and two following it, is
a bit confusing. We add this file only to remove it later and
the code hops from file to file. There seem to be some extra
steps that could be avoided.

Is there room for simplification?

Thanks,
Andi

Re: [Intel-gfx] [PATCH v4 08/10] drm/i915: Correct type of wakeref variable

[Andi Shyti]

Hi Andrzej,

On Mon, Mar 06, 2023 at 05:32:04PM +0100, Andrzej Hajda wrote:
> Wakeref has dedicated type. Assumption it will be int
> compatible forever is incorrect.
> 
> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>

easy...

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>

Andi

Re: [Intel-gfx] [PATCH v4 01/10] lib/ref_tracker: add unlocked leak print helper

[Andrzej Hajda]

On 19.03.2023 23:59, Andi Shyti wrote:
> Hi Andrzej,
> 
> [...]
> 
>> diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
>> index dc7b14aa3431e2..5e9f90bbf771b0 100644
>> --- a/lib/ref_tracker.c
>> +++ b/lib/ref_tracker.c
>> @@ -14,6 +14,38 @@ struct ref_tracker {
>>   	depot_stack_handle_t	free_stack_handle;
>>   };
>>   
>> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
>> +			   unsigned int display_limit)
> 
> can we call this ref_tracker_dir_print_locked() instead of using
> the '__'?
> 

OK, 'locked' convention looks better.

Regards
Andrzej

>> +{
>> +	struct ref_tracker *tracker;
>> +	unsigned int i = 0;
>> +
>> +	lockdep_assert_held(&dir->lock);
>> +
>> +	list_for_each_entry(tracker, &dir->list, head) {
>> +		if (i < display_limit) {
>> +			pr_err("leaked reference.\n");
>> +			if (tracker->alloc_stack_handle)
>> +				stack_depot_print(tracker->alloc_stack_handle);
>> +			i++;
>> +		} else {
>> +			break;
>> +		}
>> +	}
>> +}
>> +EXPORT_SYMBOL(__ref_tracker_dir_print);
>> +
>> +void ref_tracker_dir_print(struct ref_tracker_dir *dir,
>> +			   unsigned int display_limit)
>> +{
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&dir->lock, flags);
>> +	__ref_tracker_dir_print(dir, display_limit);
>> +	spin_unlock_irqrestore(&dir->lock, flags);
>> +}
>> +EXPORT_SYMBOL(ref_tracker_dir_print);
>> +
>>   void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>>   {
>>   	struct ref_tracker *tracker, *n;
>> @@ -27,13 +59,13 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>>   		kfree(tracker);
>>   		dir->quarantine_avail++;
>>   	}
>> -	list_for_each_entry_safe(tracker, n, &dir->list, head) {
>> -		pr_err("leaked reference.\n");
>> -		if (tracker->alloc_stack_handle)
>> -			stack_depot_print(tracker->alloc_stack_handle);
>> +	if (!list_empty(&dir->list)) {
>> +		__ref_tracker_dir_print(dir, 16);
>>   		leak = true;
>> -		list_del(&tracker->head);
>> -		kfree(tracker);
>> +		list_for_each_entry_safe(tracker, n, &dir->list, head) {
>> +			list_del(&tracker->head);
>> +			kfree(tracker);
>> +		}
> 
> Just thinking whether this should go on a different patch, but I
> don't have a strong opinion.
> 
> Looks good!
> 
> Andi

Re: [Intel-gfx] [PATCH v4 02/10] lib/ref_tracker: __ref_tracker_dir_print improve printing

[Andrzej Hajda]

On 20.03.2023 00:11, Andi Shyti wrote:
> Hi Andrzej,
> 
> looks good, few comments below,
> 
> On Mon, Mar 06, 2023 at 05:31:58PM +0100, Andrzej Hajda wrote:
>> To improve readability of ref_tracker printing following changes
>> have been performed:
>> - reports are printed per stack_handle - log is more compact,
>> - added display name for ref_tracker_dir,
>> - stack trace is printed indented, in the same printk call,
>> - total number of references is printed every time,
>> - print info about dropped references.
> 
> nit: I think you can do better with the log :)
> 
>> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> ---
>>   include/linux/ref_tracker.h | 15 ++++++--
>>   lib/ref_tracker.c           | 90 +++++++++++++++++++++++++++++++++++++++------
>>   2 files changed, 91 insertions(+), 14 deletions(-)
>>
>> diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
>> index 3e9e9df2a41f5f..a2cf1f6309adb2 100644
>> --- a/include/linux/ref_tracker.h
>> +++ b/include/linux/ref_tracker.h
>> @@ -17,12 +17,19 @@ struct ref_tracker_dir {
>>   	bool			dead;
>>   	struct list_head	list; /* List of active trackers */
>>   	struct list_head	quarantine; /* List of dead trackers */
>> +	char			name[32];
>>   #endif
>>   };
>>   
>>   #ifdef CONFIG_REF_TRACKER
>> -static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
>> -					unsigned int quarantine_count)
>> +
>> +// Temporary allow two and three arguments, until consumers are converted
> 
> I thought only Linus was allowed to use '//' :)
> 
>> +#define ref_tracker_dir_init(_d, _q, args...) _ref_tracker_dir_init(_d, _q, ##args, #_d)
>> +#define _ref_tracker_dir_init(_d, _q, _n, ...) __ref_tracker_dir_init(_d, _q, _n)
> 
> [...]
> 
>> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
>> +			   unsigned int display_limit)
>> +{
>> +	struct ref_tracker_dir_stats *stats;
>> +	unsigned int i = 0, skipped;
>> +	depot_stack_handle_t stack;
>> +	char *sbuf;
>> +
>> +	lockdep_assert_held(&dir->lock);
>> +
>> +	if (list_empty(&dir->list))
>> +		return;
>> +
>> +	stats = ref_tracker_get_stats(dir, display_limit);
>> +	if (IS_ERR(stats)) {
>> +		pr_err("%s@%pK: couldn't get stats, error %pe\n",
>> +		       dir->name, dir, stats);
>> +		return;
>>   	}
>> +
>> +	sbuf = kmalloc(STACK_BUF_SIZE, GFP_NOWAIT | __GFP_NOWARN);
>> +
>> +	for (i = 0, skipped = stats->total; i < stats->count; ++i) {
>> +		stack = stats->stacks[i].stack_handle;
>> +		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
>> +			sbuf[0] = 0;
>> +		pr_err("%s@%pK has %d/%d users at\n%s\n", dir->name, dir,
>> +		       stats->stacks[i].count, stats->total, sbuf);
> 
> what if sbuf is NULL?

Then "(NULL)" will be printed, I suspect it will occur only on very rare 
occasions.

> 
>> +		skipped -= stats->stacks[i].count;
>> +	}
>> +
>> +	if (skipped)
> 
> is skipped used to double check whether stats->count is equal to
> all the stacks[].conunts? What are the cases when skipped is > 0?

There is display_limit parameter, so the function prints up to 
display_limit reports, and brief summary on remaining ones - the skipped 
ones.

Regards
Andrzej


> 
> Andi
> 
>> +		pr_err("%s@%pK skipped reports about %d/%d users.\n",
>> +		       dir->name, dir, skipped, stats->total);
>> +
>> +	kfree(sbuf);
>> +
>> +	kfree(stats);
>>   }
>>   EXPORT_SYMBOL(__ref_tracker_dir_print);
>>   
>>
>> -- 
>> 2.34.1

Re: [Intel-gfx] [PATCH v4 03/10] lib/ref_tracker: add printing to memory buffer

[Andrzej Hajda]

On 20.03.2023 00:18, Andi Shyti wrote:
> Hi Andrzej,
> 
> This looks also good, just few questions.
> 
> On Mon, Mar 06, 2023 at 05:31:59PM +0100, Andrzej Hajda wrote:
>> In case one wants to show stats via debugfs.
> 
> shall I say it? I'll say it... you can do better with the log
> here. It's not a typo fix :)
> 
>> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
> 
> [...]
> 
>> +void __ref_tracker_dir_print(struct ref_tracker_dir *dir,
>> +			   unsigned int display_limit)
>> +{
>> +	struct ostream os = {};
>> +
>> +	__ref_tracker_dir_pr_ostream(dir, display_limit, &os);
>> +}
>>   EXPORT_SYMBOL(__ref_tracker_dir_print);
>>   
>>   void ref_tracker_dir_print(struct ref_tracker_dir *dir,
>> @@ -114,6 +141,19 @@ void ref_tracker_dir_print(struct ref_tracker_dir *dir,
>>   }
>>   EXPORT_SYMBOL(ref_tracker_dir_print);
>>   
>> +int ref_tracker_dir_snprint(struct ref_tracker_dir *dir, char *buf, size_t size)
> 
> nit: snprintf is normally referred to its variable parameter
> counterpart... I would choose a different name... how about
> ref_tracker_dir_fetch_print()?


Hmm, original ref_tracker_dir_print prints the stats to dmesg,
ref_tracker_dir_snprint prints to memory buffer, like:
- stack_depot_print and stack_depot_snprint,
- stack_trace_print and stack_trace_snprint.


> 
>> +{
>> +	struct ostream os = { .buf = buf, .size = size };
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&dir->lock, flags);
>> +	__ref_tracker_dir_pr_ostream(dir, 16, &os);
>> +	spin_unlock_irqrestore(&dir->lock, flags);
> 
> What are you trying to protect with this spinlock? what if
> the caller has already locked here? do we need a _locked()
> version?

spinlock is to serialize access to dir,
at the moment _locked version is not necessary, but it can be easily 
added if needed.

Regards
Andrzej


> 
> Thanks,
> Andi
> 
>> +	return os.used;
>> +}
>> +EXPORT_SYMBOL(ref_tracker_dir_snprint);
>> +
>>   void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
>>   {
>>   	struct ref_tracker *tracker, *n;
>>
>> -- 
>> 2.34.1

Re: [Intel-gfx] [PATCH v4 06/10] drm/i915: Separate wakeref tracking

[Andrzej Hajda]

On 20.03.2023 00:57, Andi Shyti wrote:
> Hi Andrzej,
> 
> On Mon, Mar 06, 2023 at 05:32:02PM +0100, Andrzej Hajda wrote:
>> From: Chris Wilson <chris@chris-wilson.co.uk>
>>
>> Extract the callstack tracking of intel_runtime_pm.c into its own
>> utility so that that we can reuse it for other online debugging of
>> scoped wakerefs.
>>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> ---
>>   drivers/gpu/drm/i915/Kconfig.debug           |   9 ++
>>   drivers/gpu/drm/i915/Makefile                |   4 +
>>   drivers/gpu/drm/i915/intel_runtime_pm.c      | 222 +++----------------------
>>   drivers/gpu/drm/i915/intel_wakeref.h         |   2 +-
>>   drivers/gpu/drm/i915/intel_wakeref_tracker.c | 234 +++++++++++++++++++++++++++
>>   drivers/gpu/drm/i915/intel_wakeref_tracker.h |  52 ++++++
>>   6 files changed, 319 insertions(+), 204 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
>> index 93dfb7ed970547..5fde52107e3b44 100644
>> --- a/drivers/gpu/drm/i915/Kconfig.debug
>> +++ b/drivers/gpu/drm/i915/Kconfig.debug
>> @@ -25,6 +25,7 @@ config DRM_I915_DEBUG
>>   	select PREEMPT_COUNT
>>   	select I2C_CHARDEV
>>   	select STACKDEPOT
>> +	select STACKTRACE
>>   	select DRM_DP_AUX_CHARDEV
>>   	select X86_MSR # used by igt/pm_rpm
>>   	select DRM_VGEM # used by igt/prime_vgem (dmabuf interop checks)
>> @@ -37,6 +38,7 @@ config DRM_I915_DEBUG
>>   	select DRM_I915_DEBUG_GEM
>>   	select DRM_I915_DEBUG_GEM_ONCE
>>   	select DRM_I915_DEBUG_MMIO
>> +	select DRM_I915_TRACK_WAKEREF
>>   	select DRM_I915_DEBUG_RUNTIME_PM
>>   	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
>>   	select DRM_I915_SELFTEST
>> @@ -227,11 +229,18 @@ config DRM_I915_DEBUG_VBLANK_EVADE
>>   
>>   	  If in doubt, say "N".
>>   
>> +config DRM_I915_TRACK_WAKEREF
>> +	depends on STACKDEPOT
>> +	depends on STACKTRACE
>> +	bool
>> +
>>   config DRM_I915_DEBUG_RUNTIME_PM
>>   	bool "Enable extra state checking for runtime PM"
>>   	depends on DRM_I915
>>   	default n
>>   	select STACKDEPOT
>> +	select STACKTRACE
>> +	select DRM_I915_TRACK_WAKEREF
>>   	help
>>   	  Choose this option to turn on extra state checking for the
>>   	  runtime PM functionality. This may introduce overhead during
>> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
>> index b2f91a1f826858..42daff6d575a82 100644
>> --- a/drivers/gpu/drm/i915/Makefile
>> +++ b/drivers/gpu/drm/i915/Makefile
>> @@ -81,6 +81,10 @@ i915-$(CONFIG_DEBUG_FS) += \
>>   	i915_debugfs_params.o \
>>   	display/intel_display_debugfs.o \
>>   	display/intel_pipe_crc.o
>> +
>> +i915-$(CONFIG_DRM_I915_TRACK_WAKEREF) += \
>> +	intel_wakeref_tracker.o
>> +
> 
> This patch, along with the previous one and two following it, is
> a bit confusing. We add this file only to remove it later and
> the code hops from file to file. There seem to be some extra
> steps that could be avoided.
> 
> Is there room for simplification?

The reason behind this was that i915 had it's own tracker integrated 
with i915_runtime_pm, then it was abstracted out (05,06) to allow track 
gt->wakerefs (07) and then I proposed replacement of internal tracker 
with ref_tracker (09). I wanted to keep original history of development.
I can squash all/some of this work, but I am afraid it will generate 
less readable patches - now we have separated abstract-out and replace 
steps.

Probably sending patches 05-08 1st, then proposing conversion to 
ref_tracker in another patchset would make it more clear.

Regards
Andrzej


> 
> Thanks,
> Andi