From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DE02C10F27 for ; Tue, 10 Mar 2020 14:24:13 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id ECDC622522 for ; Tue, 10 Mar 2020 14:24:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ECDC622522 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 940366E2F2; Tue, 10 Mar 2020 14:24:12 +0000 (UTC) Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 488636E2FF for ; Tue, 10 Mar 2020 14:24:10 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 20510507-1500050 for multiple; Tue, 10 Mar 2020 14:24:03 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Tue, 10 Mar 2020 14:24:03 +0000 Message-Id: <20200310142403.5953-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200310141320.24149-2-chris@chris-wilson.co.uk> References: <20200310141320.24149-2-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v2] drm/i915: Mark up racy read of active rq->engine X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" As a virtual engine may change the rq->engine to point to the active request in flight, we need to warn the compiler that an active request's engine is volatile. [ 95.017686] write (marked) to 0xffff8881e8386b10 of 8 bytes by interrupt on cpu 2: [ 95.018123] execlists_dequeue+0x762/0x2150 [i915] [ 95.018539] __execlists_submission_tasklet+0x48/0x60 [i915] [ 95.018955] execlists_submission_tasklet+0xd3/0x170 [i915] [ 95.018986] tasklet_action_common.isra.0+0x42/0xa0 [ 95.019016] __do_softirq+0xd7/0x2cd [ 95.019043] irq_exit+0xbe/0xe0 [ 95.019068] irq_work_interrupt+0xf/0x20 [ 95.019491] i915_request_retire+0x2c5/0x670 [i915] [ 95.019937] retire_requests+0xa1/0xf0 [i915] [ 95.020348] engine_retire+0xa1/0xe0 [i915] [ 95.020376] process_one_work+0x3b1/0x690 [ 95.020403] worker_thread+0x80/0x670 [ 95.020429] kthread+0x19a/0x1e0 [ 95.020454] ret_from_fork+0x1f/0x30 [ 95.020476] [ 95.020498] read to 0xffff8881e8386b10 of 8 bytes by task 8909 on cpu 3: [ 95.020918] __i915_request_commit+0x177/0x220 [i915] [ 95.021329] i915_gem_do_execbuffer+0x38c4/0x4e50 [i915] [ 95.021750] i915_gem_execbuffer2_ioctl+0x2c3/0x580 [i915] [ 95.021784] drm_ioctl_kernel+0xe4/0x120 [ 95.021809] drm_ioctl+0x297/0x4c7 [ 95.021832] ksys_ioctl+0x89/0xb0 [ 95.021865] __x64_sys_ioctl+0x42/0x60 [ 95.021901] do_syscall_64+0x6e/0x2c0 [ 95.021927] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Chris Wilson --- drivers/gpu/drm/i915/i915_request.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 74169671afb5..c0df71d7d0ff 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -977,6 +977,8 @@ emit_semaphore_wait(struct i915_request *to, struct i915_request *from, gfp_t gfp) { + const intel_engine_mask_t mask = READ_ONCE(from->engine)->mask; + if (!intel_context_use_semaphores(to->context)) goto await_fence; @@ -984,7 +986,7 @@ emit_semaphore_wait(struct i915_request *to, goto await_fence; /* Just emit the first semaphore we see as request space is limited. */ - if (already_busywaiting(to) & from->engine->mask) + if (already_busywaiting(to) & mask) goto await_fence; if (i915_request_await_start(to, from) < 0) @@ -997,7 +999,7 @@ emit_semaphore_wait(struct i915_request *to, if (__emit_semaphore_wait(to, from, from->fence.seqno)) goto await_fence; - to->sched.semaphores |= from->engine->mask; + to->sched.semaphores |= mask; to->sched.flags |= I915_SCHED_HAS_SEMAPHORE_CHAIN; return 0; @@ -1338,7 +1340,7 @@ __i915_request_add_to_timeline(struct i915_request *rq) i915_seqno_passed(prev->fence.seqno, rq->fence.seqno)); - if (is_power_of_2(prev->engine->mask | rq->engine->mask)) + if (is_power_of_2(READ_ONCE(prev->engine)->mask | rq->engine->mask)) i915_sw_fence_await_sw_fence(&rq->submit, &prev->submit, &rq->submitq); -- 2.20.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx