From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [PATCH 3/3] drm/amdgpu: Switch to interrupted wait to recover from ring hang. Date: Tue, 24 Apr 2018 11:30:03 -0500 Message-ID: <87bme8bm9g.fsf@xmission.com> References: <1524583836-12130-1-git-send-email-andrey.grodzovsky@amd.com> <1524583836-12130-4-git-send-email-andrey.grodzovsky@amd.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: (David Panariti's message of "Tue, 24 Apr 2018 16:20:16 +0000") Sender: linux-kernel-owner@vger.kernel.org To: "Panariti, David" Cc: "Grodzovsky, Andrey" , "linux-kernel@vger.kernel.org" , "amd-gfx@lists.freedesktop.org" , "Deucher, Alexander" , "Koenig, Christian" , "oleg@redhat.com" , "akpm@linux-foundation.org" List-Id: amd-gfx.lists.freedesktop.org "Panariti, David" writes: > Andrey Grodzovsky writes: >> Kind of dma_fence_wait_killable, except that we don't have such API >> (maybe worth adding ?) > Depends on how many places it would be called, or think it might be called. Can always factor on the 2nd time it's needed. > Factoring, IMO, rarely hurts. The factored function can easily be visited using `M-.' ;-> > > Also, if the wait could be very long, would a log message, something like "xxx has run for Y seconds." help? > I personally hate hanging w/no info. Ugh. This loop appears susceptible to loosing wake ups. There are races between when a wake-up happens, when we clear the sleeping state, and when we test the stat to see if we should stat awake. So yes implementing a dma_fence_wait_killable that handles of all that correctly sounds like an very good idea. Eric >> If the ring is hanging for some reason allow to recover the waiting by sending fatal signal. >> >> Originally-by: David Panariti >> Signed-off-by: Andrey Grodzovsky >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 14 ++++++++++---- >> 1 file changed, 10 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c >> index eb80edf..37a36af 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c >> @@ -421,10 +421,16 @@ int amdgpu_ctx_wait_prev_fence(struct amdgpu_ctx *ctx, unsigned ring_id) >> >> if (other) { >> signed long r; >> - r = dma_fence_wait_timeout(other, false, MAX_SCHEDULE_TIMEOUT); >> - if (r < 0) { >> - DRM_ERROR("Error (%ld) waiting for fence!\n", r); >> - return r; >> + >> + while (true) { >> + if ((r = dma_fence_wait_timeout(other, true, >> + MAX_SCHEDULE_TIMEOUT)) >= 0) >> + return 0; >> + >> + if (fatal_signal_pending(current)) { >> + DRM_ERROR("Error (%ld) waiting for fence!\n", r); >> + return r; >> + } >> } >> } >> >> -- >> 2.7.4 >> Eric