From: Lyude Paul <lyude@redhat.com> To: dri-devel@lists.freedesktop.org Cc: "Juston Li" <juston.li@intel.com>, "Imre Deak" <imre.deak@intel.com>, "Ville Syrjälä" <ville.syrjala@linux.intel.com>, "Harry Wentland" <hwentlan@amd.com>, "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>, "Maxime Ripard" <maxime.ripard@bootlin.com>, "Sean Paul" <sean@poorly.run>, "David Airlie" <airlied@linux.ie>, "Daniel Vetter" <daniel@ffwll.ch>, linux-kernel@vger.kernel.org Subject: [PATCH 26/26] drm/dp_mst: Add topology ref history tracking for debugging Date: Wed, 17 Jul 2019 21:42:49 -0400 [thread overview] Message-ID: <20190718014329.8107-27-lyude@redhat.com> (raw) In-Reply-To: <20190718014329.8107-1-lyude@redhat.com> For very subtle mistakes with topology refs, it can be rather difficult to trace them down with the debugging info that we already have. I had one such issue recently while trying to implement suspend/resume reprobing for MST, and ended up coming up with this. Inspired by Chris Wilson's wakeref tracking for i915, this adds a very similar feature to the DP MST helpers, which allows for partial tracking of topology refs for both ports and branch devices. This is a lot less advanced then wakeref tracking: we merely keep a count of all of the spots where a topology ref has been grabbed or dropped, then dump out that history in chronological order when a port or branch device's topology refcount reaches 0. So far, I've found this incredibly useful for debugging topology refcount errors. Since this has the potential to be somewhat slow and loud, we add an expert kernel config option to enable or disable this feature, CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. Cc: Juston Li <juston.li@intel.com> Cc: Imre Deak <imre.deak@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Harry Wentland <hwentlan@amd.com> Signed-off-by: Lyude Paul <lyude@redhat.com> --- drivers/gpu/drm/Kconfig | 14 ++ drivers/gpu/drm/drm_dp_mst_topology.c | 230 +++++++++++++++++++++++++- include/drm/drm_dp_mst_helper.h | 45 +++++ 3 files changed, 285 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index b9362b4f6353..e1fd27f1fa34 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -89,6 +89,20 @@ config DRM_KMS_FB_HELPER help FBDEV helpers for KMS drivers. +config DRM_DEBUG_DP_MST_TOPOLOGY_REFS + bool "Enable refcount backtrace history in the DP MST helpers" + select STACKDEPOT + depends on DRM_KMS_HELPER + depends on DEBUG_KERNEL + depends on EXPERT + help + Enables debug tracing for topology refs in DRM's DP MST helpers. A + history of each topology reference/dereference will be printed to the + kernel log once a port or branch device's topology refcount reaches 0. + + This has the potential to use a lot of memory and print some very + large kernel messages. If in doubt, say "N". + config DRM_FBDEV_EMULATION bool "Enable legacy fbdev support for your modesetting driver" depends on DRM diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index fcd3f98cbc34..443d05d563aa 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -28,6 +28,13 @@ #include <linux/sched.h> #include <linux/seq_file.h> +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) +#include <linux/stackdepot.h> +#include <linux/sort.h> +#include <linux/timekeeping.h> +#include <linux/math64.h> +#endif + #include <drm/drm_atomic.h> #include <drm/drm_atomic_helper.h> #include <drm/drm_dp_mst_helper.h> @@ -1403,12 +1410,189 @@ drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port) } EXPORT_SYMBOL(drm_dp_mst_put_port_malloc); +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + +#define STACK_DEPTH 8 + +static noinline void +__topology_ref_save(struct drm_dp_mst_topology_mgr *mgr, + struct drm_dp_mst_topology_ref_history *history, + enum drm_dp_mst_topology_ref_type type) +{ + struct drm_dp_mst_topology_ref_entry *entry = NULL; + depot_stack_handle_t backtrace; + ulong stack_entries[STACK_DEPTH]; + uint n; + int i; + + n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1); + backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL); + if (!backtrace) + goto fail_alloc; + + /* Try to find an existing entry for this backtrace */ + for (i = 0; i < history->len; i++) { + if (history->entries[i].backtrace == backtrace) { + entry = &history->entries[i]; + break; + } + } + + /* Otherwise add one */ + if (!entry) { + struct drm_dp_mst_topology_ref_entry *new; + int new_len = history->len + 1; + + new = krealloc(history->entries, sizeof(*new) * new_len, + GFP_KERNEL); + if (!new) + goto fail_alloc; + + entry = &new[history->len]; + history->len = new_len; + history->entries = new; + + entry->backtrace = backtrace; + entry->type = type; + entry->count = 0; + } + entry->count++; + entry->ts_nsec = ktime_get_ns(); + + return; +fail_alloc: + DRM_WARN_ONCE("Failed to allocate memory for topology refcount backtrace\n"); +} + +static int +topology_ref_history_cmp(const void *a, const void *b) +{ + const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b; + + if (entry_a->ts_nsec > entry_b->ts_nsec) + return 1; + else if (entry_a->ts_nsec < entry_b->ts_nsec) + return -1; + else + return 0; +} + +static inline const char * +topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type) +{ + if (type == DRM_DP_MST_TOPOLOGY_REF_GET) + return "get"; + else + return "put"; +} + +static void +__dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history, + void *ptr, const char *type_str) +{ + struct drm_printer p = drm_debug_printer(DBG_PREFIX); + char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); + int i; + + if (!buf) + return; + + if (!history->len) + goto out; + + /* First, sort the list so that it goes from oldest to newest + * reference entry + */ + sort(history->entries, history->len, sizeof(*history->entries), + topology_ref_history_cmp, NULL); + + drm_printf(&p, + "%s (%p/%px) topology count reached 0, dumping history:\n", + type_str, ptr, ptr); + + for (i = 0; i < history->len; i++) { + const struct drm_dp_mst_topology_ref_entry *entry = + &history->entries[i]; + ulong *entries; + uint nr_entries; + u64 ts_nsec = entry->ts_nsec; + u64 rem_nsec = do_div(ts_nsec, 1000000000); + + nr_entries = stack_depot_fetch(entry->backtrace, &entries); + stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 4); + + drm_printf(&p, " %d %ss (last at %5llu.%06llu):\n%s", + entry->count, + topology_ref_type_to_str(entry->type), + ts_nsec, rem_nsec / 1000, buf); + } + + /* Now free the history, since this is the only time we expose it */ + kfree(history->entries); +out: + kfree(buf); +} + +static __always_inline void +drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) +{ + __dump_topology_ref_history(&mstb->topology_ref_history, mstb, + "MSTB"); +} + +static __always_inline void +drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) +{ + __dump_topology_ref_history(&port->topology_ref_history, port, + "Port"); +} + +static __always_inline void +save_mstb_topology_ref(struct drm_dp_mst_branch *mstb, + enum drm_dp_mst_topology_ref_type type) +{ + __topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type); +} + +static __always_inline void +save_port_topology_ref(struct drm_dp_mst_port *port, + enum drm_dp_mst_topology_ref_type type) +{ + __topology_ref_save(port->mgr, &port->topology_ref_history, type); +} + +static inline void +topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_lock(&mgr->topology_ref_history_lock); +} + +static inline void +topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_unlock(&mgr->topology_ref_history_lock); +} +#else +static inline void +topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {} +static inline void +topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {} +static inline void +drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {} +static inline void +drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {} +#define save_mstb_topology_ref(mstb, type) +#define save_port_topology_ref(port, type) +#endif + static void drm_dp_destroy_mst_branch_device(struct kref *kref) { struct drm_dp_mst_branch *mstb = container_of(kref, struct drm_dp_mst_branch, topology_kref); struct drm_dp_mst_topology_mgr *mgr = mstb->mgr; + drm_dp_mst_dump_mstb_topology_history(mstb); + INIT_LIST_HEAD(&mstb->destroy_next); /* @@ -1446,11 +1630,18 @@ static void drm_dp_destroy_mst_branch_device(struct kref *kref) static int __must_check drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb) { - int ret = kref_get_unless_zero(&mstb->topology_kref); + int ret; + + topology_ref_history_lock(mstb->mgr); + ret = kref_get_unless_zero(&mstb->topology_kref); - if (ret) + if (ret) { DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref)); + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET); + } + + topology_ref_history_unlock(mstb->mgr); return ret; } @@ -1471,10 +1662,15 @@ drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb) */ static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb) { + topology_ref_history_lock(mstb->mgr); + + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET); WARN_ON(kref_read(&mstb->topology_kref) == 0); kref_get(&mstb->topology_kref); DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref)); + + topology_ref_history_unlock(mstb->mgr); } /** @@ -1492,9 +1688,14 @@ static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb) static void drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb) { + topology_ref_history_lock(mstb->mgr); + DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref) - 1); + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT); kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device); + + topology_ref_history_unlock(mstb->mgr); } static void drm_dp_destroy_port(struct kref *kref) @@ -1503,6 +1704,8 @@ static void drm_dp_destroy_port(struct kref *kref) container_of(kref, struct drm_dp_mst_port, topology_kref); struct drm_dp_mst_topology_mgr *mgr = port->mgr; + drm_dp_mst_dump_port_topology_history(port); + /* There's nothing that needs locking to destroy an input port yet */ if (port->input) { drm_dp_mst_put_port_malloc(port); @@ -1546,12 +1749,18 @@ static void drm_dp_destroy_port(struct kref *kref) static int __must_check drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port) { - int ret = kref_get_unless_zero(&port->topology_kref); + int ret; - if (ret) + topology_ref_history_lock(port->mgr); + ret = kref_get_unless_zero(&port->topology_kref); + + if (ret) { DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref)); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET); + } + topology_ref_history_unlock(port->mgr); return ret; } @@ -1570,10 +1779,15 @@ drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port) */ static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port) { + topology_ref_history_lock(port->mgr); + WARN_ON(kref_read(&port->topology_kref) == 0); kref_get(&port->topology_kref); DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref)); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET); + + topology_ref_history_unlock(port->mgr); } /** @@ -1589,9 +1803,14 @@ static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port) */ static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port) { + topology_ref_history_lock(port->mgr); + DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref) - 1); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT); kref_put(&port->topology_kref, drm_dp_destroy_port); + + topology_ref_history_unlock(port->mgr); } static struct drm_dp_mst_branch * @@ -4414,6 +4633,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, mutex_init(&mgr->payload_lock); mutex_init(&mgr->destroy_connector_lock); mutex_init(&mgr->up_req_lock); +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + mutex_init(&mgr->topology_ref_history_lock); +#endif INIT_LIST_HEAD(&mgr->tx_msg_downq); INIT_LIST_HEAD(&mgr->destroy_connector_list); INIT_LIST_HEAD(&mgr->destroy_branch_device_list); diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index eece28525d52..1e05ffee226f 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -26,6 +26,26 @@ #include <drm/drm_dp_helper.h> #include <drm/drm_atomic.h> +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) +#include <linux/stackdepot.h> +#include <linux/timekeeping.h> + +enum drm_dp_mst_topology_ref_type { + DRM_DP_MST_TOPOLOGY_REF_GET, + DRM_DP_MST_TOPOLOGY_REF_PUT, +}; + +struct drm_dp_mst_topology_ref_history { + struct drm_dp_mst_topology_ref_entry { + enum drm_dp_mst_topology_ref_type type; + int count; + ktime_t ts_nsec; + depot_stack_handle_t backtrace; + } *entries; + int len; +}; +#endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */ + struct drm_dp_mst_branch; /** @@ -92,6 +112,14 @@ struct drm_dp_mst_port { */ struct kref malloc_kref; +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history: A history of each topology + * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. + */ + struct drm_dp_mst_topology_ref_history topology_ref_history; +#endif + u8 port_num; bool input; bool mcs; @@ -162,6 +190,14 @@ struct drm_dp_mst_branch { */ struct kref malloc_kref; +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history: A history of each topology + * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. + */ + struct drm_dp_mst_topology_ref_history topology_ref_history; +#endif + /** * @destroy_next: linked-list entry used by * drm_dp_destroy_connector_work() @@ -628,6 +664,15 @@ struct drm_dp_mst_topology_mgr { * transmissions. */ struct work_struct up_req_work; + +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history_lock: protects + * &drm_dp_mst_port.topology_ref_history and + * &drm_dp_mst_branch.topology_ref_history. + */ + struct mutex topology_ref_history_lock; +#endif }; int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, -- 2.21.0
WARNING: multiple messages have this Message-ID (diff)
From: Lyude Paul <lyude@redhat.com> To: dri-devel@lists.freedesktop.org Cc: Maxime Ripard <maxime.ripard@bootlin.com>, Sean Paul <sean@poorly.run>, linux-kernel@vger.kernel.org, David Airlie <airlied@linux.ie>, Juston Li <juston.li@intel.com>, Harry Wentland <hwentlan@amd.com> Subject: [PATCH 26/26] drm/dp_mst: Add topology ref history tracking for debugging Date: Wed, 17 Jul 2019 21:42:49 -0400 [thread overview] Message-ID: <20190718014329.8107-27-lyude@redhat.com> (raw) In-Reply-To: <20190718014329.8107-1-lyude@redhat.com> For very subtle mistakes with topology refs, it can be rather difficult to trace them down with the debugging info that we already have. I had one such issue recently while trying to implement suspend/resume reprobing for MST, and ended up coming up with this. Inspired by Chris Wilson's wakeref tracking for i915, this adds a very similar feature to the DP MST helpers, which allows for partial tracking of topology refs for both ports and branch devices. This is a lot less advanced then wakeref tracking: we merely keep a count of all of the spots where a topology ref has been grabbed or dropped, then dump out that history in chronological order when a port or branch device's topology refcount reaches 0. So far, I've found this incredibly useful for debugging topology refcount errors. Since this has the potential to be somewhat slow and loud, we add an expert kernel config option to enable or disable this feature, CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. Cc: Juston Li <juston.li@intel.com> Cc: Imre Deak <imre.deak@intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Harry Wentland <hwentlan@amd.com> Signed-off-by: Lyude Paul <lyude@redhat.com> --- drivers/gpu/drm/Kconfig | 14 ++ drivers/gpu/drm/drm_dp_mst_topology.c | 230 +++++++++++++++++++++++++- include/drm/drm_dp_mst_helper.h | 45 +++++ 3 files changed, 285 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig index b9362b4f6353..e1fd27f1fa34 100644 --- a/drivers/gpu/drm/Kconfig +++ b/drivers/gpu/drm/Kconfig @@ -89,6 +89,20 @@ config DRM_KMS_FB_HELPER help FBDEV helpers for KMS drivers. +config DRM_DEBUG_DP_MST_TOPOLOGY_REFS + bool "Enable refcount backtrace history in the DP MST helpers" + select STACKDEPOT + depends on DRM_KMS_HELPER + depends on DEBUG_KERNEL + depends on EXPERT + help + Enables debug tracing for topology refs in DRM's DP MST helpers. A + history of each topology reference/dereference will be printed to the + kernel log once a port or branch device's topology refcount reaches 0. + + This has the potential to use a lot of memory and print some very + large kernel messages. If in doubt, say "N". + config DRM_FBDEV_EMULATION bool "Enable legacy fbdev support for your modesetting driver" depends on DRM diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index fcd3f98cbc34..443d05d563aa 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -28,6 +28,13 @@ #include <linux/sched.h> #include <linux/seq_file.h> +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) +#include <linux/stackdepot.h> +#include <linux/sort.h> +#include <linux/timekeeping.h> +#include <linux/math64.h> +#endif + #include <drm/drm_atomic.h> #include <drm/drm_atomic_helper.h> #include <drm/drm_dp_mst_helper.h> @@ -1403,12 +1410,189 @@ drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port) } EXPORT_SYMBOL(drm_dp_mst_put_port_malloc); +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + +#define STACK_DEPTH 8 + +static noinline void +__topology_ref_save(struct drm_dp_mst_topology_mgr *mgr, + struct drm_dp_mst_topology_ref_history *history, + enum drm_dp_mst_topology_ref_type type) +{ + struct drm_dp_mst_topology_ref_entry *entry = NULL; + depot_stack_handle_t backtrace; + ulong stack_entries[STACK_DEPTH]; + uint n; + int i; + + n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1); + backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL); + if (!backtrace) + goto fail_alloc; + + /* Try to find an existing entry for this backtrace */ + for (i = 0; i < history->len; i++) { + if (history->entries[i].backtrace == backtrace) { + entry = &history->entries[i]; + break; + } + } + + /* Otherwise add one */ + if (!entry) { + struct drm_dp_mst_topology_ref_entry *new; + int new_len = history->len + 1; + + new = krealloc(history->entries, sizeof(*new) * new_len, + GFP_KERNEL); + if (!new) + goto fail_alloc; + + entry = &new[history->len]; + history->len = new_len; + history->entries = new; + + entry->backtrace = backtrace; + entry->type = type; + entry->count = 0; + } + entry->count++; + entry->ts_nsec = ktime_get_ns(); + + return; +fail_alloc: + DRM_WARN_ONCE("Failed to allocate memory for topology refcount backtrace\n"); +} + +static int +topology_ref_history_cmp(const void *a, const void *b) +{ + const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b; + + if (entry_a->ts_nsec > entry_b->ts_nsec) + return 1; + else if (entry_a->ts_nsec < entry_b->ts_nsec) + return -1; + else + return 0; +} + +static inline const char * +topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type) +{ + if (type == DRM_DP_MST_TOPOLOGY_REF_GET) + return "get"; + else + return "put"; +} + +static void +__dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history, + void *ptr, const char *type_str) +{ + struct drm_printer p = drm_debug_printer(DBG_PREFIX); + char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); + int i; + + if (!buf) + return; + + if (!history->len) + goto out; + + /* First, sort the list so that it goes from oldest to newest + * reference entry + */ + sort(history->entries, history->len, sizeof(*history->entries), + topology_ref_history_cmp, NULL); + + drm_printf(&p, + "%s (%p/%px) topology count reached 0, dumping history:\n", + type_str, ptr, ptr); + + for (i = 0; i < history->len; i++) { + const struct drm_dp_mst_topology_ref_entry *entry = + &history->entries[i]; + ulong *entries; + uint nr_entries; + u64 ts_nsec = entry->ts_nsec; + u64 rem_nsec = do_div(ts_nsec, 1000000000); + + nr_entries = stack_depot_fetch(entry->backtrace, &entries); + stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 4); + + drm_printf(&p, " %d %ss (last at %5llu.%06llu):\n%s", + entry->count, + topology_ref_type_to_str(entry->type), + ts_nsec, rem_nsec / 1000, buf); + } + + /* Now free the history, since this is the only time we expose it */ + kfree(history->entries); +out: + kfree(buf); +} + +static __always_inline void +drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) +{ + __dump_topology_ref_history(&mstb->topology_ref_history, mstb, + "MSTB"); +} + +static __always_inline void +drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) +{ + __dump_topology_ref_history(&port->topology_ref_history, port, + "Port"); +} + +static __always_inline void +save_mstb_topology_ref(struct drm_dp_mst_branch *mstb, + enum drm_dp_mst_topology_ref_type type) +{ + __topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type); +} + +static __always_inline void +save_port_topology_ref(struct drm_dp_mst_port *port, + enum drm_dp_mst_topology_ref_type type) +{ + __topology_ref_save(port->mgr, &port->topology_ref_history, type); +} + +static inline void +topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_lock(&mgr->topology_ref_history_lock); +} + +static inline void +topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_unlock(&mgr->topology_ref_history_lock); +} +#else +static inline void +topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {} +static inline void +topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {} +static inline void +drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {} +static inline void +drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {} +#define save_mstb_topology_ref(mstb, type) +#define save_port_topology_ref(port, type) +#endif + static void drm_dp_destroy_mst_branch_device(struct kref *kref) { struct drm_dp_mst_branch *mstb = container_of(kref, struct drm_dp_mst_branch, topology_kref); struct drm_dp_mst_topology_mgr *mgr = mstb->mgr; + drm_dp_mst_dump_mstb_topology_history(mstb); + INIT_LIST_HEAD(&mstb->destroy_next); /* @@ -1446,11 +1630,18 @@ static void drm_dp_destroy_mst_branch_device(struct kref *kref) static int __must_check drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb) { - int ret = kref_get_unless_zero(&mstb->topology_kref); + int ret; + + topology_ref_history_lock(mstb->mgr); + ret = kref_get_unless_zero(&mstb->topology_kref); - if (ret) + if (ret) { DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref)); + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET); + } + + topology_ref_history_unlock(mstb->mgr); return ret; } @@ -1471,10 +1662,15 @@ drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb) */ static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb) { + topology_ref_history_lock(mstb->mgr); + + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET); WARN_ON(kref_read(&mstb->topology_kref) == 0); kref_get(&mstb->topology_kref); DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref)); + + topology_ref_history_unlock(mstb->mgr); } /** @@ -1492,9 +1688,14 @@ static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb) static void drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb) { + topology_ref_history_lock(mstb->mgr); + DRM_DEBUG("mstb %p/%px (%d)\n", mstb, mstb, kref_read(&mstb->topology_kref) - 1); + save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT); kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device); + + topology_ref_history_unlock(mstb->mgr); } static void drm_dp_destroy_port(struct kref *kref) @@ -1503,6 +1704,8 @@ static void drm_dp_destroy_port(struct kref *kref) container_of(kref, struct drm_dp_mst_port, topology_kref); struct drm_dp_mst_topology_mgr *mgr = port->mgr; + drm_dp_mst_dump_port_topology_history(port); + /* There's nothing that needs locking to destroy an input port yet */ if (port->input) { drm_dp_mst_put_port_malloc(port); @@ -1546,12 +1749,18 @@ static void drm_dp_destroy_port(struct kref *kref) static int __must_check drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port) { - int ret = kref_get_unless_zero(&port->topology_kref); + int ret; - if (ret) + topology_ref_history_lock(port->mgr); + ret = kref_get_unless_zero(&port->topology_kref); + + if (ret) { DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref)); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET); + } + topology_ref_history_unlock(port->mgr); return ret; } @@ -1570,10 +1779,15 @@ drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port) */ static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port) { + topology_ref_history_lock(port->mgr); + WARN_ON(kref_read(&port->topology_kref) == 0); kref_get(&port->topology_kref); DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref)); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET); + + topology_ref_history_unlock(port->mgr); } /** @@ -1589,9 +1803,14 @@ static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port) */ static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port) { + topology_ref_history_lock(port->mgr); + DRM_DEBUG("port %p/%px (%d)\n", port, port, kref_read(&port->topology_kref) - 1); + save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT); kref_put(&port->topology_kref, drm_dp_destroy_port); + + topology_ref_history_unlock(port->mgr); } static struct drm_dp_mst_branch * @@ -4414,6 +4633,9 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, mutex_init(&mgr->payload_lock); mutex_init(&mgr->destroy_connector_lock); mutex_init(&mgr->up_req_lock); +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + mutex_init(&mgr->topology_ref_history_lock); +#endif INIT_LIST_HEAD(&mgr->tx_msg_downq); INIT_LIST_HEAD(&mgr->destroy_connector_list); INIT_LIST_HEAD(&mgr->destroy_branch_device_list); diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h index eece28525d52..1e05ffee226f 100644 --- a/include/drm/drm_dp_mst_helper.h +++ b/include/drm/drm_dp_mst_helper.h @@ -26,6 +26,26 @@ #include <drm/drm_dp_helper.h> #include <drm/drm_atomic.h> +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) +#include <linux/stackdepot.h> +#include <linux/timekeeping.h> + +enum drm_dp_mst_topology_ref_type { + DRM_DP_MST_TOPOLOGY_REF_GET, + DRM_DP_MST_TOPOLOGY_REF_PUT, +}; + +struct drm_dp_mst_topology_ref_history { + struct drm_dp_mst_topology_ref_entry { + enum drm_dp_mst_topology_ref_type type; + int count; + ktime_t ts_nsec; + depot_stack_handle_t backtrace; + } *entries; + int len; +}; +#endif /* IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) */ + struct drm_dp_mst_branch; /** @@ -92,6 +112,14 @@ struct drm_dp_mst_port { */ struct kref malloc_kref; +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history: A history of each topology + * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. + */ + struct drm_dp_mst_topology_ref_history topology_ref_history; +#endif + u8 port_num; bool input; bool mcs; @@ -162,6 +190,14 @@ struct drm_dp_mst_branch { */ struct kref malloc_kref; +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history: A history of each topology + * reference/dereference. See CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS. + */ + struct drm_dp_mst_topology_ref_history topology_ref_history; +#endif + /** * @destroy_next: linked-list entry used by * drm_dp_destroy_connector_work() @@ -628,6 +664,15 @@ struct drm_dp_mst_topology_mgr { * transmissions. */ struct work_struct up_req_work; + +#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS) + /** + * @topology_ref_history_lock: protects + * &drm_dp_mst_port.topology_ref_history and + * &drm_dp_mst_branch.topology_ref_history. + */ + struct mutex topology_ref_history_lock; +#endif }; int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, -- 2.21.0 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-07-18 1:45 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-07-18 1:42 [PATCH 00/26] DP MST Refactors + debugging tools + suspend/resume reprobing Lyude Paul 2019-07-18 1:42 ` [PATCH 01/26] drm/dp_mst: Move link address dumping into a function Lyude Paul 2019-08-08 19:53 ` Daniel Vetter 2019-08-08 19:53 ` Daniel Vetter 2019-08-26 21:51 ` Lyude Paul 2019-08-27 16:16 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 02/26] drm/dp_mst: Destroy mstbs from destroy_connector_work Lyude Paul 2019-08-13 13:00 ` Daniel Vetter 2019-08-26 22:07 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 03/26] drm/dp_mst: Move test_calc_pbn_mode() into an actual selftest Lyude Paul 2019-08-13 13:01 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 04/26] drm/print: Add drm_err_printer() Lyude Paul 2019-08-13 13:04 ` Daniel Vetter 2019-08-13 13:04 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 05/26] drm/dp_mst: Add sideband down request tracing + selftests Lyude Paul 2019-08-13 14:50 ` Daniel Vetter 2019-08-13 14:50 ` Daniel Vetter 2019-08-27 16:43 ` Lyude Paul 2019-08-27 16:43 ` Lyude Paul 2019-08-27 16:49 ` Lyude Paul 2019-08-27 17:15 ` Daniel Vetter 2019-08-27 17:15 ` Daniel Vetter 2019-08-31 0:31 ` Lyude Paul 2019-09-03 7:40 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 06/26] drm/dp_mst: Move PDT teardown for ports into destroy_connector_work Lyude Paul 2019-08-13 14:52 ` Daniel Vetter 2019-08-13 14:52 ` Daniel Vetter 2019-08-30 23:46 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 07/26] drm/dp_mst: Get rid of list clear in drm_dp_finish_destroy_port() Lyude Paul 2019-08-13 14:55 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 08/26] drm/dp_mst: Refactor drm_dp_send_enum_path_resources Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-08-14 15:05 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 09/26] drm/dp_mst: Remove huge conditional in drm_dp_mst_handle_up_req() Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-08-13 14:56 ` Daniel Vetter 2019-08-13 14:56 ` Daniel Vetter 2019-07-18 1:42 ` [PATCH 10/26] drm/dp_mst: Constify guid in drm_dp_get_mst_branch_by_guid() Lyude Paul 2019-07-18 1:42 ` [PATCH 11/26] drm/dp_mst: Refactor drm_dp_mst_handle_up_req() Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 12/26] drm/dp_mst: Refactor drm_dp_mst_handle_down_rep() Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 13/26] drm/dp_mst: Destroy topology_mgr mutexes Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 14/26] drm/dp_mst: Cleanup drm_dp_send_link_address() a bit Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 15/26] drm/dp_mst: Refactor pdt setup/teardown, add more locking Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 16/26] drm/dp_mst: Rename drm_dp_add_port and drm_dp_update_port Lyude Paul 2019-07-18 1:42 ` [PATCH 17/26] drm/dp_mst: Remove lies in {up,down}_rep_recv documentation Lyude Paul 2019-07-18 1:42 ` [PATCH 18/26] drm/dp_mst: Handle UP requests asynchronously Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 19/26] drm/dp_mst: Protect drm_dp_mst_port members with connection_mutex Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 20/26] drm/dp_mst: Don't forget to update port->input in drm_dp_mst_handle_conn_stat() Lyude Paul 2019-07-18 1:42 ` [PATCH 21/26] drm/nouveau: Don't grab runtime PM refs for HPD IRQs Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 22/26] drm/amdgpu: Iterate through DRM connectors correctly Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 23/26] drm/amdgpu/dm: Resume short HPD IRQs before resuming MST topology Lyude Paul 2019-07-18 1:42 ` [PATCH 24/26] drm/dp_mst: Add basic topology reprobing when resuming Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` [PATCH 25/26] drm/dp_mst: Also print unhashed pointers for malloc/topology references Lyude Paul 2019-07-18 1:42 ` Lyude Paul 2019-07-18 1:42 ` Lyude Paul [this message] 2019-07-18 1:42 ` [PATCH 26/26] drm/dp_mst: Add topology ref history tracking for debugging Lyude Paul
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