From 3a55dc895e524033a55524e94b5e12c6f98c80ff Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 10 Mar 2020 14:13:20 +0000 Subject: [PATCH] drm/i915/execlists: Mark up data-races in virtual engines 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 Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20200310141320.24149-3-chris@chris-wilson.co.uk --- 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 0604b11a2842..ee378a089dd5 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; } @@ -2033,13 +2033,14 @@ 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; @@ -4944,7 +4945,7 @@ 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