When being used across multiple real engines inside a virtual engine,
the intel_context.inflight is updated atomically, and so we must
annotate the racy read from outside the owning context.
[11142.482846] BUG: KCSAN: data-race in __execlists_submission_tasklet [i915] / __execlists_submission_tasklet [i915]
[11142.482867]
[11142.482878] write (marked) to 0xffff8881f257b5e0 of 8 bytes by interrupt on cpu 2:
[11142.483107] __execlists_submission_tasklet+0x1d33/0x2120 [i915]
[11142.483336] execlists_submission_tasklet+0xd3/0x170 [i915]
[11142.483355] tasklet_action_common.isra.0+0x42/0xa0
[11142.483371] __do_softirq+0xd7/0x2cd
[11142.483384] irq_exit+0xbe/0xe0
[11142.483401] do_IRQ+0x51/0x100
[11142.483424] ret_from_intr+0x0/0x1c
[11142.483446] do_idle+0x133/0x1f0
[11142.483465] cpu_startup_entry+0x14/0x16
[11142.483483] start_secondary+0x120/0x180
[11142.483498] secondary_startup_64+0xa4/0xb0
[11142.483512]
[11142.483528] read to 0xffff8881f257b5e0 of 8 bytes by interrupt on cpu 1:
[11142.483755] __execlists_submission_tasklet+0x14e/0x2120 [i915]
[11142.483981] execlists_submission_tasklet+0xd3/0x170 [i915]
[11142.483999] tasklet_action_common.isra.0+0x42/0xa0
[11142.484014] __do_softirq+0xd7/0x2cd
[11142.484028] do_softirq_own_stack+0x2a/0x40
[11142.484046] do_softirq.part.0+0x26/0x30
[11142.484071] __local_bh_enable_ip+0x46/0x50
[11142.484299] i915_gem_do_execbuffer+0x39c1/0x4e50 [i915]
[11142.484528] i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915]
[11142.484546] drm_ioctl_kernel+0xe4/0x120
[11142.484559] drm_ioctl+0x297/0x4c7
[11142.484572] ksys_ioctl+0x89/0xb0
[11142.484586] __x64_sys_ioctl+0x42/0x60
[11142.484610] do_syscall_64+0x6e/0x2c0
[11142.484627] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_context_types.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 11278343b9b5..0f3b68b95c56 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -45,8 +45,8 @@ struct intel_context {
struct intel_engine_cs *engine;
struct intel_engine_cs *inflight;
-#define intel_context_inflight(ce) ptr_mask_bits((ce)->inflight, 2)
-#define intel_context_inflight_count(ce) ptr_unmask_bits((ce)->inflight, 2)
+#define intel_context_inflight(ce) ptr_mask_bits(READ_ONCE((ce)->inflight), 2)
+#define intel_context_inflight_count(ce) ptr_unmask_bits(READ_ONCE((ce)->inflight), 2)
struct i915_address_space *vm;
struct i915_gem_context __rcu *gem_context;
--
2.20.1
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