[Intel-gfx] [PATCH] drm/i915: Avoid use-after-free of ctx in request tracepoints

[Chris Wilson]

trace_i915_gem_request_out may be used after the request is completed,
and so the request may have been retired on another thread, invalidating
the rq->ctx. Avoid dereferencing rq->ctx in the tracepoint by switching
to the fence context id instead, updating all tracepoints to match.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_trace.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h
index 5503f5ab1e98..66404c5aee82 100644
--- a/drivers/gpu/drm/i915/i915_trace.h
+++ b/drivers/gpu/drm/i915/i915_trace.h
@@ -590,7 +590,7 @@ TRACE_EVENT(i915_gem_request_queue,
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
 			   __entry->ring = req->engine->id;
-			   __entry->ctx = req->ctx->hw_id;
+			   __entry->ctx = req->fence.context;
 			   __entry->seqno = req->fence.seqno;
 			   __entry->flags = flags;
 			   ),
@@ -637,8 +637,8 @@ DECLARE_EVENT_CLASS(i915_gem_request,
 
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
-			   __entry->ctx = req->ctx->hw_id;
 			   __entry->ring = req->engine->id;
+			   __entry->ctx = req->fence.context;
 			   __entry->seqno = req->fence.seqno;
 			   __entry->global = req->global_seqno;
 			   ),
@@ -681,7 +681,7 @@ DECLARE_EVENT_CLASS(i915_gem_request_hw,
 		    TP_fast_assign(
 			           __entry->dev = req->i915->drm.primary->index;
 			           __entry->ring = req->engine->id;
-			           __entry->ctx = req->ctx->hw_id;
+			           __entry->ctx = req->fence.context;
 			           __entry->seqno = req->fence.seqno;
 			           __entry->global_seqno = req->global_seqno;
 			           __entry->port = port;
@@ -776,7 +776,7 @@ TRACE_EVENT(i915_gem_request_wait_begin,
 	    TP_fast_assign(
 			   __entry->dev = req->i915->drm.primary->index;
 			   __entry->ring = req->engine->id;
-			   __entry->ctx = req->ctx->hw_id;
+			   __entry->ctx = req->fence.context;
 			   __entry->seqno = req->fence.seqno;
 			   __entry->global = req->global_seqno;
 			   __entry->flags = flags;
-- 
2.11.0