From 9467397f417dd7b5d0db91452f0474e79716a527 Mon Sep 17 00:00:00 2001 From: John Harrison Date: Thu, 26 Jan 2023 16:28:36 -0800 Subject: [PATCH] drm/i915: Fix request ref counting during error capture & debugfs dump [ Upstream commit 86d8ddc74124c3fdfc139f246ba6da15e45e86e3 ] When GuC support was added to error capture, the reference counting around the request object was broken. Fix it up. The context based search manages the spinlocking around the search internally. So it needs to grab the reference count internally as well. The execlist only request based search relies on external locking, so it needs an external reference count but within the spinlock not outside it. The only other caller of the context based search is the code for dumping engine state to debugfs. That code wasn't previously getting an explicit reference at all as it does everything while holding the execlist specific spinlock. So, that needs updaing as well as that spinlock doesn't help when using GuC submission. Rather than trying to conditionally get/put depending on submission model, just change it to always do the get/put. v2: Explicitly document adding an extra blank line in some dense code (Andy Shevchenko). Fix multiple potential null pointer derefs in case of no request found (some spotted by Tvrtko, but there was more!). Also fix a leaked request in case of !started and another in __guc_reset_context now that intel_context_find_active_request is actually reference counting the returned request. v3: Add a _get suffix to intel_context_find_active_request now that it grabs a reference (Daniele). v4: Split the intel_guc_find_hung_context change to a separate patch and rename intel_context_find_active_request_get to intel_context_get_active_request (Tvrtko). v5: s/locking/reference counting/ in commit message (Tvrtko) Fixes: dc0dad365c5e ("drm/i915/guc: Fix for error capture after full GPU reset with GuC") Fixes: 573ba126aef3 ("drm/i915/guc: Capture error state on context reset") Signed-off-by: John Harrison Reviewed-by: Daniele Ceraolo Spurio Acked-by: Tvrtko Ursulin Cc: Matthew Brost Cc: Jani Nikula Cc: Joonas Lahtinen Cc: Rodrigo Vivi Cc: Andrzej Hajda Cc: Matthew Auld Cc: Matt Roper Cc: Umesh Nerlige Ramappa Cc: Michael Cheng Cc: Lucas De Marchi Cc: Tejas Upadhyay Cc: Andy Shevchenko Cc: Aravind Iddamsetty Cc: Alan Previn Cc: Bruce Chang Link: https://patchwork.freedesktop.org/patch/msgid/20230127002842.3169194-3-John.C.Harrison@Intel.com (cherry picked from commit 3700e353781e27f1bc7222f51f2cc36cbeb9b4ec) Signed-off-by: Rodrigo Vivi Signed-off-by: Sasha Levin --- drivers/gpu/drm/i915/gt/intel_context.c | 4 +++- drivers/gpu/drm/i915/gt/intel_context.h | 3 +-- drivers/gpu/drm/i915/gt/intel_engine_cs.c | 6 +++++- drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 3 ++- drivers/gpu/drm/i915/i915_gpu_error.c | 13 ++++++------- 5 files changed, 17 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index e94365b08f1ef..2aa63ec521b89 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -528,7 +528,7 @@ struct i915_request *intel_context_create_request(struct intel_context *ce) return rq; } -struct i915_request *intel_context_find_active_request(struct intel_context *ce) +struct i915_request *intel_context_get_active_request(struct intel_context *ce) { struct intel_context *parent = intel_context_to_parent(ce); struct i915_request *rq, *active = NULL; @@ -552,6 +552,8 @@ struct i915_request *intel_context_find_active_request(struct intel_context *ce) active = rq; } + if (active) + active = i915_request_get_rcu(active); spin_unlock_irqrestore(&parent->guc_state.lock, flags); return active; diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h index be09fb2e883a5..4ab6c8ddd6ecc 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.h +++ b/drivers/gpu/drm/i915/gt/intel_context.h @@ -268,8 +268,7 @@ int intel_context_prepare_remote_request(struct intel_context *ce, struct i915_request *intel_context_create_request(struct intel_context *ce); -struct i915_request * -intel_context_find_active_request(struct intel_context *ce); +struct i915_request *intel_context_get_active_request(struct intel_context *ce); static inline bool intel_context_is_barrier(const struct intel_context *ce) { diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c index fcbccd8d244e9..4327c6d91ce94 100644 --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c @@ -2201,9 +2201,11 @@ static void engine_dump_active_requests(struct intel_engine_cs *engine, struct d if (guc) { ce = intel_engine_get_hung_context(engine); if (ce) - hung_rq = intel_context_find_active_request(ce); + hung_rq = intel_context_get_active_request(ce); } else { hung_rq = intel_engine_execlist_find_hung_request(engine); + if (hung_rq) + hung_rq = i915_request_get_rcu(hung_rq); } if (hung_rq) @@ -2214,6 +2216,8 @@ static void engine_dump_active_requests(struct intel_engine_cs *engine, struct d else intel_engine_dump_active_requests(&engine->sched_engine->requests, hung_rq, m); + if (hung_rq) + i915_request_put(hung_rq); } void intel_engine_dump(struct intel_engine_cs *engine, 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 259162002c3ac..0ec07dad1dcf1 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1685,7 +1685,7 @@ static void __guc_reset_context(struct intel_context *ce, intel_engine_mask_t st goto next_context; guilty = false; - rq = intel_context_find_active_request(ce); + rq = intel_context_get_active_request(ce); if (!rq) { head = ce->ring->tail; goto out_replay; @@ -1698,6 +1698,7 @@ static void __guc_reset_context(struct intel_context *ce, intel_engine_mask_t st head = intel_ring_wrap(ce->ring, rq->head); __i915_request_reset(rq, guilty); + i915_request_put(rq); out_replay: guc_reset_state(ce, head, guilty); next_context: diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c index 9ea2fe34e7d30..a8ee4cd2ff164 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -1603,7 +1603,7 @@ capture_engine(struct intel_engine_cs *engine, ce = intel_engine_get_hung_context(engine); if (ce) { intel_engine_clear_hung_context(engine); - rq = intel_context_find_active_request(ce); + rq = intel_context_get_active_request(ce); if (!rq || !i915_request_started(rq)) goto no_request_capture; } else { @@ -1614,21 +1614,18 @@ capture_engine(struct intel_engine_cs *engine, if (!intel_uc_uses_guc_submission(&engine->gt->uc)) { spin_lock_irqsave(&engine->sched_engine->lock, flags); rq = intel_engine_execlist_find_hung_request(engine); + if (rq) + rq = i915_request_get_rcu(rq); spin_unlock_irqrestore(&engine->sched_engine->lock, flags); } } - if (rq) - rq = i915_request_get_rcu(rq); - if (!rq) goto no_request_capture; capture = intel_engine_coredump_add_request(ee, rq, ATOMIC_MAYFAIL); - if (!capture) { - i915_request_put(rq); + if (!capture) goto no_request_capture; - } if (dump_flags & CORE_DUMP_FLAG_IS_GUC_CAPTURE) intel_guc_capture_get_matching_node(engine->gt, ee, ce); @@ -1638,6 +1635,8 @@ capture_engine(struct intel_engine_cs *engine, return ee; no_request_capture: + if (rq) + i915_request_put(rq); kfree(ee); return NULL; }