The virtual engine passes tokens back and forth to its backing physical
engines.
[ 57.372993] BUG: KCSAN: data-race in execlists_dequeue [i915] / virtual_submission_tasklet [i915]
[ 57.373012]
[ 57.373023] write to 0xffff8881f47324c0 of 4 bytes by interrupt on cpu 2:
[ 57.373241] execlists_dequeue+0x6fa/0x2150 [i915]
[ 57.373458] __execlists_submission_tasklet+0x48/0x60 [i915]
[ 57.373677] execlists_submission_tasklet+0xd3/0x170 [i915]
[ 57.373694] tasklet_action_common.isra.0+0x42/0xa0
[ 57.373709] __do_softirq+0xd7/0x2cd
[ 57.373723] irq_exit+0xbe/0xe0
[ 57.373735] do_IRQ+0x51/0x100
[ 57.373748] ret_from_intr+0x0/0x1c
[ 57.373963] engine_retire+0x89/0xe0 [i915]
[ 57.373977] process_one_work+0x3b1/0x690
[ 57.373990] worker_thread+0x80/0x670
[ 57.374004] kthread+0x19a/0x1e0
[ 57.374017] ret_from_fork+0x1f/0x30
[ 57.374027]
[ 57.374038] read to 0xffff8881f47324c0 of 4 bytes by interrupt on cpu 3:
[ 57.374256] virtual_submission_tasklet+0x27/0x5a0 [i915]
[ 57.374273] tasklet_action_common.isra.0+0x42/0xa0
[ 57.374288] __do_softirq+0xd7/0x2cd
[ 57.374302] run_ksoftirqd+0x15/0x20
[ 57.374315] smpboot_thread_fn+0x1ab/0x300
[ 57.374329] kthread+0x19a/0x1e0
[ 57.374342] ret_from_fork+0x1f/0x30
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 15b81be08fcc..8122f4bc2e90 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1004,7 +1004,7 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
i915_request_cancel_breadcrumb(rq);
spin_unlock(&rq->lock);
}
- rq->engine = owner;
+ WRITE_ONCE(rq->engine, owner);
owner->submit_request(rq);
active = NULL;
}
@@ -2023,13 +2023,14 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
"",
yesno(engine != ve->siblings[0]));
- ve->request = NULL;
- ve->base.execlists.queue_priority_hint = INT_MIN;
+ WRITE_ONCE(ve->request, NULL);
+ WRITE_ONCE(ve->base.execlists.queue_priority_hint,
+ INT_MIN);
rb_erase_cached(rb, &execlists->virtual);
RB_CLEAR_NODE(rb);
GEM_BUG_ON(!(rq->execution_mask & engine->mask));
- rq->engine = engine;
+ WRITE_ONCE(rq->engine, engine);
if (engine != ve->siblings[0]) {
u32 *regs = ve->context.lrc_reg_state;
@@ -4934,7 +4935,7 @@ static intel_engine_mask_t virtual_submission_mask(struct virtual_engine *ve)
static void virtual_submission_tasklet(unsigned long data)
{
struct virtual_engine * const ve = (struct virtual_engine *)data;
- const int prio = ve->base.execlists.queue_priority_hint;
+ const int prio = READ_ONCE(ve->base.execlists.queue_priority_hint);
intel_engine_mask_t mask;
unsigned int n;
--
2.20.1
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