From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3EF9A28DBA for ; Mon, 16 Oct 2023 14:55:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="nLyQKLYs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AEE35C433C9; Mon, 16 Oct 2023 14:55:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697468131; bh=mQXktEU1cLdEr+vH2MPPu08REej0GhNFJnafqhfnP/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nLyQKLYsUp2Hs7PKD9Oaa6RBV+xtSd0y19D6cXqimOR/yCYsjrZQv5s9XMYiSNl57 a/gEjm/75tOwhiHPoroY2wcU9yKuO5VFVxi1xDKIAdyktCxHpNwwAetcuSdpR6j+uX WNgM6Bva8zYguPSeV62zOnuJ/PNMX7fxZVnes/f0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yunxiang Li , =?UTF-8?q?Christian=20K=C3=B6nig?= , Alex Deucher Subject: [PATCH 6.5 164/191] dma-buf: add dma_fence_timestamp helper Date: Mon, 16 Oct 2023 10:42:29 +0200 Message-ID: <20231016084019.205078815@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231016084015.400031271@linuxfoundation.org> References: <20231016084015.400031271@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian König commit b83ce9cb4a465b8f9a3fa45561b721a9551f60e3 upstream. When a fence signals there is a very small race window where the timestamp isn't updated yet. sync_file solves this by busy waiting for the timestamp to appear, but on other ocassions didn't handled this correctly. Provide a dma_fence_timestamp() helper function for this and use it in all appropriate cases. Another alternative would be to grab the spinlock when that happens. v2 by teddy: add a wait parameter to wait for the timestamp to show up, in case the accurate timestamp is needed and/or the timestamp is not based on ktime (e.g. hw timestamp) v3 chk: drop the parameter again for unified handling Signed-off-by: Yunxiang Li Signed-off-by: Christian König Fixes: 1774baa64f93 ("drm/scheduler: Change scheduled fence track v2") Reviewed-by: Alex Deucher CC: stable@vger.kernel.org Link: https://patchwork.freedesktop.org/patch/msgid/20230929104725.2358-1-christian.koenig@amd.com Signed-off-by: Greg Kroah-Hartman --- drivers/dma-buf/dma-fence-unwrap.c | 13 ++++--------- drivers/dma-buf/sync_file.c | 9 +++------ drivers/gpu/drm/scheduler/sched_main.c | 2 +- include/linux/dma-fence.h | 19 +++++++++++++++++++ 4 files changed, 27 insertions(+), 16 deletions(-) --- a/drivers/dma-buf/dma-fence-unwrap.c +++ b/drivers/dma-buf/dma-fence-unwrap.c @@ -76,16 +76,11 @@ struct dma_fence *__dma_fence_unwrap_mer dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) { if (!dma_fence_is_signaled(tmp)) { ++count; - } else if (test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, - &tmp->flags)) { - if (ktime_after(tmp->timestamp, timestamp)) - timestamp = tmp->timestamp; } else { - /* - * Use the current time if the fence is - * currently signaling. - */ - timestamp = ktime_get(); + ktime_t t = dma_fence_timestamp(tmp); + + if (ktime_after(t, timestamp)) + timestamp = t; } } } --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -268,13 +268,10 @@ static int sync_fill_fence_info(struct d sizeof(info->driver_name)); info->status = dma_fence_get_status(fence); - while (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && - !test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) - cpu_relax(); info->timestamp_ns = - test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ? - ktime_to_ns(fence->timestamp) : - ktime_set(0, 0); + dma_fence_is_signaled(fence) ? + ktime_to_ns(dma_fence_timestamp(fence)) : + ktime_set(0, 0); return info->status; } --- a/drivers/gpu/drm/scheduler/sched_main.c +++ b/drivers/gpu/drm/scheduler/sched_main.c @@ -929,7 +929,7 @@ drm_sched_get_cleanup_job(struct drm_gpu if (next) { next->s_fence->scheduled.timestamp = - job->s_fence->finished.timestamp; + dma_fence_timestamp(&job->s_fence->finished); /* start TO timer for next job */ drm_sched_start_timeout(sched); } --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -568,6 +568,25 @@ static inline void dma_fence_set_error(s fence->error = error; } +/** + * dma_fence_timestamp - helper to get the completion timestamp of a fence + * @fence: fence to get the timestamp from. + * + * After a fence is signaled the timestamp is updated with the signaling time, + * but setting the timestamp can race with tasks waiting for the signaling. This + * helper busy waits for the correct timestamp to appear. + */ +static inline ktime_t dma_fence_timestamp(struct dma_fence *fence) +{ + if (WARN_ON(!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))) + return ktime_get(); + + while (!test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags)) + cpu_relax(); + + return fence->timestamp; +} + signed long dma_fence_wait_timeout(struct dma_fence *, bool intr, signed long timeout); signed long dma_fence_wait_any_timeout(struct dma_fence **fences,