[PATCH 08/13] drivers/oprofile: convert stats to use seqnum_ops

From: Shuah Khan <skhan@linuxfoundation.org>
To: rric@kernel.org, gregkh@linuxfoundation.org,
	keescook@chromium.org, peterz@infradead.org
Cc: Shuah Khan <skhan@linuxfoundation.org>,
	oprofile-list@lists.sf.net, linux-kernel@vger.kernel.org
Subject: [PATCH 08/13] drivers/oprofile: convert stats to use seqnum_ops
Date: Tue, 10 Nov 2020 12:53:34 -0700	[thread overview]
Message-ID: <908cbac7285d11fd494e64b71c5e54e6b1b1c564.1605027593.git.skhan@linuxfoundation.org> (raw)
In-Reply-To: <cover.1605027593.git.skhan@linuxfoundation.org>

seqnum_ops api is introduced to be used when a variable is used as
a sequence/stat counter and doesn't guard object lifetimes. This
clearly differentiates atomic_t usages that guard object lifetimes.

seqnum32 variables wrap around to INT_MIN when it overflows and
should not be used to guard resource lifetimes, device usage and
open counts that control state changes, and pm states.

atomic_t variables used for stats are atomic counters. Overflow will
wrap around and reset the stats and no change with the conversion.

Convert them to use seqnum_ops.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
---
 drivers/oprofile/buffer_sync.c    |  9 +++++----
 drivers/oprofile/event_buffer.c   |  3 ++-
 drivers/oprofile/oprof.c          |  3 ++-
 drivers/oprofile/oprofile_stats.c | 11 ++++++-----
 drivers/oprofile/oprofile_stats.h | 11 ++++++-----
 drivers/oprofile/oprofilefs.c     |  3 ++-
 include/linux/oprofile.h          |  3 ++-
 7 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index cc917865f13a..0503d467429b 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -34,6 +34,7 @@
 #include <linux/sched/mm.h>
 #include <linux/sched/task.h>
 #include <linux/gfp.h>
+#include <linux/seqnum_ops.h>
 
 #include "oprofile_stats.h"
 #include "event_buffer.h"
@@ -347,7 +348,7 @@ static void add_data(struct op_entry *entry, struct mm_struct *mm)
 		if (cookie == NO_COOKIE)
 			offset = pc;
 		if (cookie == INVALID_COOKIE) {
-			atomic_inc(&oprofile_stats.sample_lost_no_mapping);
+			seqnum32_inc(&oprofile_stats.sample_lost_no_mapping);
 			offset = pc;
 		}
 		if (cookie != last_cookie) {
@@ -391,14 +392,14 @@ add_sample(struct mm_struct *mm, struct op_sample *s, int in_kernel)
 	/* add userspace sample */
 
 	if (!mm) {
-		atomic_inc(&oprofile_stats.sample_lost_no_mm);
+		seqnum32_inc(&oprofile_stats.sample_lost_no_mm);
 		return 0;
 	}
 
 	cookie = lookup_dcookie(mm, s->eip, &offset);
 
 	if (cookie == INVALID_COOKIE) {
-		atomic_inc(&oprofile_stats.sample_lost_no_mapping);
+		seqnum32_inc(&oprofile_stats.sample_lost_no_mapping);
 		return 0;
 	}
 
@@ -556,7 +557,7 @@ void sync_buffer(int cpu)
 		/* ignore backtraces if failed to add a sample */
 		if (state == sb_bt_start) {
 			state = sb_bt_ignore;
-			atomic_inc(&oprofile_stats.bt_lost_no_mapping);
+			seqnum32_inc(&oprofile_stats.bt_lost_no_mapping);
 		}
 	}
 	release_mm(mm);
diff --git a/drivers/oprofile/event_buffer.c b/drivers/oprofile/event_buffer.c
index 6c9edc8bbc95..6ec2f1ed8d94 100644
--- a/drivers/oprofile/event_buffer.c
+++ b/drivers/oprofile/event_buffer.c
@@ -19,6 +19,7 @@
 #include <linux/dcookies.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
+#include <linux/seqnum_ops.h>
 
 #include "oprof.h"
 #include "event_buffer.h"
@@ -53,7 +54,7 @@ void add_event_entry(unsigned long value)
 	}
 
 	if (buffer_pos == buffer_size) {
-		atomic_inc(&oprofile_stats.event_lost_overflow);
+		seqnum32_inc(&oprofile_stats.event_lost_overflow);
 		return;
 	}
 
diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
index ed2c3ec07024..f3183ef0f607 100644
--- a/drivers/oprofile/oprof.c
+++ b/drivers/oprofile/oprof.c
@@ -15,6 +15,7 @@
 #include <linux/workqueue.h>
 #include <linux/time.h>
 #include <linux/mutex.h>
+#include <linux/seqnum_ops.h>
 
 #include "oprof.h"
 #include "event_buffer.h"
@@ -110,7 +111,7 @@ static void switch_worker(struct work_struct *work)
 	if (oprofile_ops.switch_events())
 		return;
 
-	atomic_inc(&oprofile_stats.multiplex_counter);
+	seqnum32_inc(&oprofile_stats.multiplex_counter);
 	start_switch_worker();
 }
 
diff --git a/drivers/oprofile/oprofile_stats.c b/drivers/oprofile/oprofile_stats.c
index 59659cea4582..04e9b2a0d35a 100644
--- a/drivers/oprofile/oprofile_stats.c
+++ b/drivers/oprofile/oprofile_stats.c
@@ -11,6 +11,7 @@
 #include <linux/smp.h>
 #include <linux/cpumask.h>
 #include <linux/threads.h>
+#include <linux/seqnum_ops.h>
 
 #include "oprofile_stats.h"
 #include "cpu_buffer.h"
@@ -30,11 +31,11 @@ void oprofile_reset_stats(void)
 		cpu_buf->sample_invalid_eip = 0;
 	}
 
-	atomic_set(&oprofile_stats.sample_lost_no_mm, 0);
-	atomic_set(&oprofile_stats.sample_lost_no_mapping, 0);
-	atomic_set(&oprofile_stats.event_lost_overflow, 0);
-	atomic_set(&oprofile_stats.bt_lost_no_mapping, 0);
-	atomic_set(&oprofile_stats.multiplex_counter, 0);
+	seqnum32_set(&oprofile_stats.sample_lost_no_mm, 0);
+	seqnum32_set(&oprofile_stats.sample_lost_no_mapping, 0);
+	seqnum32_set(&oprofile_stats.event_lost_overflow, 0);
+	seqnum32_set(&oprofile_stats.bt_lost_no_mapping, 0);
+	seqnum32_set(&oprofile_stats.multiplex_counter, 0);
 }
 
 
diff --git a/drivers/oprofile/oprofile_stats.h b/drivers/oprofile/oprofile_stats.h
index 1fc622bd1834..229bcbb16527 100644
--- a/drivers/oprofile/oprofile_stats.h
+++ b/drivers/oprofile/oprofile_stats.h
@@ -11,13 +11,14 @@
 #define OPROFILE_STATS_H
 
 #include <linux/atomic.h>
+#include <linux/seqnum_ops.h>
 
 struct oprofile_stat_struct {
-	atomic_t sample_lost_no_mm;
-	atomic_t sample_lost_no_mapping;
-	atomic_t bt_lost_no_mapping;
-	atomic_t event_lost_overflow;
-	atomic_t multiplex_counter;
+	struct seqnum32 sample_lost_no_mm;
+	struct seqnum32 sample_lost_no_mapping;
+	struct seqnum32 bt_lost_no_mapping;
+	struct seqnum32 event_lost_overflow;
+	struct seqnum32 multiplex_counter;
 };
 
 extern struct oprofile_stat_struct oprofile_stats;
diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c
index 0875f2f122b3..c5749b9aca11 100644
--- a/drivers/oprofile/oprofilefs.c
+++ b/drivers/oprofile/oprofilefs.c
@@ -17,6 +17,7 @@
 #include <linux/fs_context.h>
 #include <linux/pagemap.h>
 #include <linux/uaccess.h>
+#include <linux/seqnum_ops.h>
 
 #include "oprof.h"
 
@@ -193,7 +194,7 @@ static const struct file_operations atomic_ro_fops = {
 
 
 int oprofilefs_create_ro_atomic(struct dentry *root,
-	char const *name, atomic_t *val)
+	char const *name, struct seqnum32 *val)
 {
 	return __oprofilefs_create_file(root, name,
 					&atomic_ro_fops, 0444, val);
diff --git a/include/linux/oprofile.h b/include/linux/oprofile.h
index b2a0f15f11fe..f770254a0c8a 100644
--- a/include/linux/oprofile.h
+++ b/include/linux/oprofile.h
@@ -19,6 +19,7 @@
 #include <linux/errno.h>
 #include <linux/printk.h>
 #include <linux/atomic.h>
+#include <linux/seqnum_ops.h>
  
 /* Each escaped entry is prefixed by ESCAPE_CODE
  * then one of the following codes, then the
@@ -140,7 +141,7 @@ int oprofilefs_create_ro_ulong(struct dentry * root,
  
 /** Create a file for read-only access to an atomic_t. */
 int oprofilefs_create_ro_atomic(struct dentry * root,
-	char const * name, atomic_t * val);
+	char const *name, struct seqnum32 *val);
  
 /** create a directory */
 struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name);
-- 
2.27.0

