Re: [PATCH v5 1/8] drm/i915/guc: Fix locking when searching for a hung request

[Ceraolo Spurio, Daniele]

On 1/25/2023 4:54 PM, john.c.harri...@intel.com wrote:

From: John Harrison <john.c.harri...@intel.com>

intel_guc_find_hung_context() was not acquiring the correct spinlock
before searching the request list. So fix that up. While at it, add
some extra whitespace padding for readability.

Fixes: dc0dad365c5e ("drm/i915/guc: Fix for error capture after full GPU reset with 
GuC")
Cc: John Harrison <john.c.harri...@intel.com>
Cc: Matthew Brost <matthew.br...@intel.com>
Cc: Jani Nikula <jani.nik...@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>
Cc: Matt Roper <matthew.d.ro...@intel.com>
Cc: Umesh Nerlige Ramappa <umesh.nerlige.rama...@intel.com>
Cc: Michael Cheng <michael.ch...@intel.com>
Cc: Lucas De Marchi <lucas.demar...@intel.com>
Cc: Tejas Upadhyay <tejaskumarx.surendrakumar.upadh...@intel.com>
Cc: Chris Wilson <chris.p.wil...@intel.com>
Cc: Bruce Chang <yu.bruce.ch...@intel.com>
Cc: Alan Previn <alan.previn.teres.ale...@intel.com>
Cc: Matthew Auld <matthew.a...@intel.com>
Cc: intel-...@lists.freedesktop.org
Signed-off-by: John Harrison <john.c.harri...@intel.com>

Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospu...@intel.com>

Daniele

---
  drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 11 +++++++++++
  1 file changed, 11 insertions(+)

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 b436dd7f12e42..3b34a82d692be 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -4820,6 +4820,8 @@ void intel_guc_find_hung_context(struct intel_engine_cs 
*engine)

xa_lock_irqsave(&guc->context_lookup, flags);

        xa_for_each(&guc->context_lookup, index, ce) {
+               bool found;
+
                if (!kref_get_unless_zero(&ce->ref))
                        continue;

@@ -4836,10 +4838,18 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)

                                goto next;
                }

+ found = false;

+               spin_lock(&ce->guc_state.lock);
                list_for_each_entry(rq, &ce->guc_state.requests, sched.link) {
                        if (i915_test_request_state(rq) != I915_REQUEST_ACTIVE)
                                continue;

+ found = true;

+                       break;
+               }
+               spin_unlock(&ce->guc_state.lock);
+
+               if (found) {
                        intel_engine_set_hung_context(engine, ce);

/* Can only cope with one hang at a time... */

@@ -4847,6 +4857,7 @@ void intel_guc_find_hung_context(struct intel_engine_cs 
*engine)
                        xa_lock(&guc->context_lookup);
                        goto done;
                }
+
  next:
                intel_context_put(ce);
                xa_lock(&guc->context_lookup);