From patchwork Fri Jul 23 07:58:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Michel_D=C3=A4nzer?= X-Patchwork-Id: 75955 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1m6qBM-001ndn-Mp; Fri, 23 Jul 2021 08:05:21 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234317AbhGWHYp (ORCPT + 1 other); Fri, 23 Jul 2021 03:24:45 -0400 Received: from mail.netline.ch ([148.251.143.180]:36189 "EHLO netline-mail3.netline.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233619AbhGWHYo (ORCPT ); Fri, 23 Jul 2021 03:24:44 -0400 X-Greylist: delayed 377 seconds by postgrey-1.27 at vger.kernel.org; Fri, 23 Jul 2021 03:24:44 EDT Received: from localhost (localhost [127.0.0.1]) by netline-mail3.netline.ch (Postfix) with ESMTP id B409920201B; Fri, 23 Jul 2021 09:58:58 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at netline-mail3.netline.ch Received: from netline-mail3.netline.ch ([127.0.0.1]) by localhost (netline-mail3.netline.ch [127.0.0.1]) (amavisd-new, port 10024) with LMTP id QA7ph4I77QHY; Fri, 23 Jul 2021 09:58:58 +0200 (CEST) Received: from kaveri (24.99.2.85.dynamic.wline.res.cust.swisscom.ch [85.2.99.24]) by netline-mail3.netline.ch (Postfix) with ESMTPA id 6202F20201A; Fri, 23 Jul 2021 09:58:58 +0200 (CEST) Received: from daenzer by kaveri with local (Exim 4.94.2) (envelope-from ) id 1m6q5B-00014N-F3; Fri, 23 Jul 2021 09:58:57 +0200 From: =?utf-8?q?Michel_D=C3=A4nzer?= To: =?utf-8?q?Christian_K=C3=B6nig?= Cc: Sumit Semwal , dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Subject: [PATCH] dma-buf/poll: Get a file reference for outstanding fence callbacks Date: Fri, 23 Jul 2021 09:58:57 +0200 Message-Id: <20210723075857.4065-1-michel@daenzer.net> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.4 (--) X-LSpam-Report: No, score=-2.4 required=5.0 tests=BAYES_00=-1.9,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1,RCVD_IN_DNSWL_NONE=-0.0001 autolearn=ham autolearn_force=no From: Michel Dänzer This makes sure we don't hit the BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active); in dma_buf_release, which could be triggered by user space closing the dma-buf file description while there are outstanding fence callbacks from dma_buf_poll. Cc: stable@vger.kernel.org Signed-off-by: Michel Dänzer --- drivers/dma-buf/dma-buf.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 6c520c9bd93c..ec25498a971f 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -65,12 +65,9 @@ static void dma_buf_release(struct dentry *dentry) BUG_ON(dmabuf->vmapping_counter); /* - * Any fences that a dma-buf poll can wait on should be signaled - * before releasing dma-buf. This is the responsibility of each - * driver that uses the reservation objects. - * - * If you hit this BUG() it means someone dropped their ref to the - * dma-buf while still having pending operation to the buffer. + * If you hit this BUG() it could mean: + * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else + * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback */ BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active); @@ -196,6 +193,7 @@ static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb) { struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb; + struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll); unsigned long flags; spin_lock_irqsave(&dcb->poll->lock, flags); @@ -203,6 +201,8 @@ static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb) dcb->active = 0; spin_unlock_irqrestore(&dcb->poll->lock, flags); dma_fence_put(fence); + /* Paired with get_file in dma_buf_poll */ + fput(dmabuf->file); } static bool dma_buf_poll_shared(struct dma_resv *resv, @@ -278,6 +278,9 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) spin_unlock_irq(&dmabuf->poll.lock); if (events & EPOLLOUT) { + /* Paired with fput in dma_buf_poll_cb */ + get_file(dmabuf->file); + if (!dma_buf_poll_shared(resv, dcb) && !dma_buf_poll_excl(resv, dcb)) /* No callback queued, wake up any other waiters */ @@ -299,6 +302,9 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) spin_unlock_irq(&dmabuf->poll.lock); if (events & EPOLLIN) { + /* Paired with fput in dma_buf_poll_cb */ + get_file(dmabuf->file); + if (!dma_buf_poll_excl(resv, dcb)) /* No callback queued, wake up any other waiters */ dma_buf_poll_cb(NULL, &dcb->cb);