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* [Intel-gfx] [PATCH] drm/i915/gt: Defend against concurrent updates to execlists->active
@ 2020-03-09 11:24 Chris Wilson
  2020-03-09 13:14 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
                   ` (4 more replies)
  0 siblings, 5 replies; 10+ messages in thread
From: Chris Wilson @ 2020-03-09 11:24 UTC (permalink / raw)
  To: intel-gfx

[  206.875637] BUG: KCSAN: data-race in __i915_schedule+0x7fc/0x930 [i915]
[  206.875654]
[  206.875666] race at unknown origin, with read to 0xffff8881f7644480 of 8 bytes by task 703 on cpu 3:
[  206.875901]  __i915_schedule+0x7fc/0x930 [i915]
[  206.876130]  __bump_priority+0x63/0x80 [i915]
[  206.876361]  __i915_sched_node_add_dependency+0x258/0x300 [i915]
[  206.876593]  i915_sched_node_add_dependency+0x50/0xa0 [i915]
[  206.876824]  i915_request_await_dma_fence+0x1da/0x530 [i915]
[  206.877057]  i915_request_await_object+0x2fe/0x470 [i915]
[  206.877287]  i915_gem_do_execbuffer+0x45dc/0x4c20 [i915]
[  206.877517]  i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[  206.877535]  drm_ioctl_kernel+0xe4/0x120
[  206.877549]  drm_ioctl+0x297/0x4c7
[  206.877563]  ksys_ioctl+0x89/0xb0
[  206.877577]  __x64_sys_ioctl+0x42/0x60
[  206.877591]  do_syscall_64+0x6e/0x2c0
[  206.877606]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

References: https://gitlab.freedesktop.org/drm/intel/issues/1318
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_engine.h | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index 29c8c03c5caa..f267f51c457c 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -107,7 +107,17 @@ execlists_num_ports(const struct intel_engine_execlists * const execlists)
 static inline struct i915_request *
 execlists_active(const struct intel_engine_execlists *execlists)
 {
-	return *READ_ONCE(execlists->active);
+	struct i915_request * const *cur = READ_ONCE(execlists->active);
+	struct i915_request * const *old;
+	struct i915_request *active;
+
+	do {
+		old = cur;
+		active = READ_ONCE(*cur);
+		cur = READ_ONCE(execlists->active);
+	} while (cur != old);
+
+	return active;
 }
 
 static inline void
-- 
2.20.1

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^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2020-03-10 13:57 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-03-09 11:24 [Intel-gfx] [PATCH] drm/i915/gt: Defend against concurrent updates to execlists->active Chris Wilson
2020-03-09 13:14 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2020-03-09 15:34 ` [Intel-gfx] [PATCH] " Mika Kuoppala
2020-03-09 16:19   ` Chris Wilson
2020-03-09 16:38     ` Mika Kuoppala
2020-03-09 17:01       ` Chris Wilson
2020-03-09 17:05 ` [Intel-gfx] [PATCH v2] " Chris Wilson
2020-03-09 17:41   ` Mika Kuoppala
2020-03-09 19:34 ` [Intel-gfx] ✓ Fi.CI.IGT: success for " Patchwork
2020-03-10 13:57 ` [Intel-gfx] ✗ Fi.CI.BUILD: failure for drm/i915/gt: Defend against concurrent updates to execlists->active (rev2) Patchwork

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