All of lore.kernel.org
 help / color / mirror / Atom feed
From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [Intel-gfx] [PATCH 3/3] drm/i915/execlists: Mark up data-races in virtual engines
Date: Tue, 10 Mar 2020 14:13:20 +0000	[thread overview]
Message-ID: <20200310141320.24149-3-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <20200310141320.24149-1-chris@chris-wilson.co.uk>

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@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 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

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  parent reply	other threads:[~2020-03-10 14:13 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-10 14:13 [Intel-gfx] [PATCH 1/3] drm/i915/gt: Mark up racy reads for intel_context.inflight Chris Wilson
2020-03-10 14:13 ` [Intel-gfx] [PATCH 2/3] drm/i915: Mark up racy read of active rq->engine Chris Wilson
2020-03-10 14:24   ` [Intel-gfx] [PATCH v2] " Chris Wilson
2020-03-10 15:29     ` Mika Kuoppala
2020-03-10 14:13 ` Chris Wilson [this message]
2020-03-10 15:35   ` [Intel-gfx] [PATCH 3/3] drm/i915/execlists: Mark up data-races in virtual engines Mika Kuoppala
2020-03-10 15:01 ` [Intel-gfx] [PATCH 1/3] drm/i915/gt: Mark up racy reads for intel_context.inflight Mika Kuoppala
2020-03-11  8:40 ` [Intel-gfx] ✓ Fi.CI.BAT: success for series starting with [1/3] drm/i915/gt: Mark up racy reads for intel_context.inflight (rev2) Patchwork
2020-03-11 14:33 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200310141320.24149-3-chris@chris-wilson.co.uk \
    --to=chris@chris-wilson.co.uk \
    --cc=intel-gfx@lists.freedesktop.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.