From patchwork Thu Apr 3 10:13:54 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philipp Stanner X-Patchwork-Id: 878516 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 04CAD1F12EF; Thu, 3 Apr 2025 10:15:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743675345; cv=none; b=JNeliLDAH7v6y3ZuIqpwAgdgDsfRMLGgtnzyls/0/qQzHqULGRgyhvpCOrd0QkRx/u87oUWI4ucTgXAssD/ev10MhXpESryA8tskvF/UMJ3aqX+kplI/9qrYypc2ap3d28RcBLYYqDjLsQlgg5SKLt3qp/wtQNzdMF37ZxoHVAk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743675345; c=relaxed/simple; bh=Y5lfKBIHipEzLx3pRzlfCRd1YVUuZIoPVyyxseg8ZRI=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=V726sFrc/WZzJVWVhenxsnaRGLJ388zvybY/cnSX3Ne1gxijObECviXUzUC1lx1uSbe2UndQK6AqxWfNCs3/Ni9cbLHlBCGwLiEB1MqKqDjPFGvVPnVvqBmsxG9Lk6DKlqu1gsfOSmeerGecDQno8CjXaQ/3gBBjcBt1abVTwP0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cVlBjpfV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cVlBjpfV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4932CC4CEE3; Thu, 3 Apr 2025 10:15:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1743675344; bh=Y5lfKBIHipEzLx3pRzlfCRd1YVUuZIoPVyyxseg8ZRI=; h=From:To:Cc:Subject:Date:From; b=cVlBjpfVoI5iXt6biIGOugHzCgetf6T+X7OsygIQ3EeJaFKlp3/iRtaZBPnKqjMQa NcETm9+IbOnfpk11YK2QIQcAYDO5LPw/INgTCDj/+JKbglsTrfPCGLMCtd1Grbhlyp qaGhsFdGbjL4j/15R6gPTw4BYqZTDmgFxaUMUqSL1zUz0XHgXey6Hj6j1oqsuma2Xw 481dS1xkvUZYeR5J+BvJo82JjXpa3lktdGLpEEfNPx1mXIboVHH4+ZfpU96uvEI5o7 IDEY760y5oExSByhc4tianjkdziAGaJm/9ub1gGLx7gQMxiscYh/TeUuB73M4KeRmF qc/SAU8hNQJQQ== From: Philipp Stanner To: Lyude Paul , Danilo Krummrich , David Airlie , Simona Vetter , Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= Cc: dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, Philipp Stanner , stable@vger.kernel.org Subject: [PATCH v2] drm/nouveau: Prevent signalled fences in pending list Date: Thu, 3 Apr 2025 12:13:54 +0200 Message-ID: <20250403101353.42880-2-phasta@kernel.org> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Nouveau currently relies on the assumption that dma_fences will only ever get signalled through nouveau_fence_signal(), which takes care of removing a signalled fence from the list nouveau_fence_chan.pending. This self-imposed rule is violated in nouveau_fence_done(), where dma_fence_is_signaled() can signal the fence without removing it from the list. This enables accesses to already signalled fences through the list, which is a bug. Furthermore, it must always be possible to use standard dma_fence methods an a dma_fence and observe valid behavior. The canonical way of ensuring that signalling a fence has additional effects is to add those effects to a callback and register it on that fence. Move the code from nouveau_fence_signal() into a dma_fence callback. Register that callback when creating the fence. Cc: # 4.10+ Signed-off-by: Philipp Stanner --- Changes in v2: - Remove Fixes: tag. (Danilo) - Remove integer "drop" and call nvif_event_block() in the fence callback. (Danilo) --- drivers/gpu/drm/nouveau/nouveau_fence.c | 52 +++++++++++++------------ drivers/gpu/drm/nouveau/nouveau_fence.h | 1 + 2 files changed, 29 insertions(+), 24 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c index 7cc84472cece..cf510ef9641a 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fence.c +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c @@ -50,24 +50,24 @@ nouveau_fctx(struct nouveau_fence *fence) return container_of(fence->base.lock, struct nouveau_fence_chan, lock); } -static int -nouveau_fence_signal(struct nouveau_fence *fence) +static void +nouveau_fence_cleanup_cb(struct dma_fence *dfence, struct dma_fence_cb *cb) { - int drop = 0; + struct nouveau_fence_chan *fctx; + struct nouveau_fence *fence; + + fence = container_of(dfence, struct nouveau_fence, base); + fctx = nouveau_fctx(fence); - dma_fence_signal_locked(&fence->base); list_del(&fence->head); rcu_assign_pointer(fence->channel, NULL); if (test_bit(DMA_FENCE_FLAG_USER_BITS, &fence->base.flags)) { - struct nouveau_fence_chan *fctx = nouveau_fctx(fence); - if (!--fctx->notify_ref) - drop = 1; + nvif_event_block(&fctx->event); } dma_fence_put(&fence->base); - return drop; } static struct nouveau_fence * @@ -93,8 +93,7 @@ nouveau_fence_context_kill(struct nouveau_fence_chan *fctx, int error) if (error) dma_fence_set_error(&fence->base, error); - if (nouveau_fence_signal(fence)) - nvif_event_block(&fctx->event); + dma_fence_signal_locked(&fence->base); } fctx->killed = 1; spin_unlock_irqrestore(&fctx->lock, flags); @@ -127,11 +126,10 @@ nouveau_fence_context_free(struct nouveau_fence_chan *fctx) kref_put(&fctx->fence_ref, nouveau_fence_context_put); } -static int +static void nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx) { struct nouveau_fence *fence; - int drop = 0; u32 seq = fctx->read(chan); while (!list_empty(&fctx->pending)) { @@ -140,10 +138,8 @@ nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fc if ((int)(seq - fence->base.seqno) < 0) break; - drop |= nouveau_fence_signal(fence); + dma_fence_signal_locked(&fence->base); } - - return drop; } static void @@ -152,7 +148,6 @@ nouveau_fence_uevent_work(struct work_struct *work) struct nouveau_fence_chan *fctx = container_of(work, struct nouveau_fence_chan, uevent_work); unsigned long flags; - int drop = 0; spin_lock_irqsave(&fctx->lock, flags); if (!list_empty(&fctx->pending)) { @@ -161,11 +156,8 @@ nouveau_fence_uevent_work(struct work_struct *work) fence = list_entry(fctx->pending.next, typeof(*fence), head); chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock)); - if (nouveau_fence_update(chan, fctx)) - drop = 1; + nouveau_fence_update(chan, fctx); } - if (drop) - nvif_event_block(&fctx->event); spin_unlock_irqrestore(&fctx->lock, flags); } @@ -235,6 +227,19 @@ nouveau_fence_emit(struct nouveau_fence *fence) &fctx->lock, fctx->context, ++fctx->sequence); kref_get(&fctx->fence_ref); + fence->cb.func = nouveau_fence_cleanup_cb; + /* Adding a callback runs into __dma_fence_enable_signaling(), which will + * ultimately run into nouveau_fence_no_signaling(), where a WARN_ON + * would fire because the refcount can be dropped there. + * + * Increment the refcount here temporarily to work around that. + */ + dma_fence_get(&fence->base); + ret = dma_fence_add_callback(&fence->base, &fence->cb, nouveau_fence_cleanup_cb); + dma_fence_put(&fence->base); + if (ret) + return ret; + ret = fctx->emit(fence); if (!ret) { dma_fence_get(&fence->base); @@ -246,8 +251,7 @@ nouveau_fence_emit(struct nouveau_fence *fence) return -ENODEV; } - if (nouveau_fence_update(chan, fctx)) - nvif_event_block(&fctx->event); + nouveau_fence_update(chan, fctx); list_add_tail(&fence->head, &fctx->pending); spin_unlock_irq(&fctx->lock); @@ -270,8 +274,8 @@ nouveau_fence_done(struct nouveau_fence *fence) spin_lock_irqsave(&fctx->lock, flags); chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock)); - if (chan && nouveau_fence_update(chan, fctx)) - nvif_event_block(&fctx->event); + if (chan) + nouveau_fence_update(chan, fctx); spin_unlock_irqrestore(&fctx->lock, flags); } return dma_fence_is_signaled(&fence->base); diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.h b/drivers/gpu/drm/nouveau/nouveau_fence.h index 8bc065acfe35..e6b2df7fdc42 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fence.h +++ b/drivers/gpu/drm/nouveau/nouveau_fence.h @@ -10,6 +10,7 @@ struct nouveau_bo; struct nouveau_fence { struct dma_fence base; + struct dma_fence_cb cb; struct list_head head;