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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3878CC433F5 for ; Mon, 22 Nov 2021 13:07:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239192AbhKVNKF (ORCPT ); Mon, 22 Nov 2021 08:10:05 -0500 Received: from mail.kernel.org ([198.145.29.99]:43162 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239534AbhKVNJ6 (ORCPT ); Mon, 22 Nov 2021 08:09:58 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id BE45D60234; Mon, 22 Nov 2021 13:06:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637586412; bh=bDV2XBuDXfGYQR2A/0P2rnv3uJW5Rq7BHbRbY+2TNAM=; h=Subject:To:Cc:From:Date:From; b=u/ad80NpS+9T0fxBgGlqYPU/zAo7MDUbXSP464+En8B6rzcPE1PxbRtWVSsRcEgPI jP1BR4mDyvvSw8dwRLk2YdgKcaJaJJe5kPmyEt3HE//Yje+6/XIuWz1TipIdVX2kLr lU4m12JOkPyYpxiEpm4XSeMuU7EPnbjy2XWN7kuw= Subject: FAILED: patch "[PATCH] dma-buf/poll: Get a file reference for outstanding fence" failed to apply to 5.10-stable tree To: mdaenzer@redhat.com, christian.koenig@amd.com Cc: From: Date: Mon, 22 Nov 2021 14:06:41 +0100 Message-ID: <16375864012941@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From ff2d23843f7fb4f13055be5a4a9a20ddd04e6e9c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Michel=20D=C3=A4nzer?= Date: Fri, 23 Jul 2021 09:58:57 +0200 Subject: [PATCH] dma-buf/poll: Get a file reference for outstanding fence callbacks MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Christian König Link: https://patchwork.freedesktop.org/patch/msgid/20210723075857.4065-1-michel@daenzer.net Signed-off-by: Christian König diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index beb504a92d60..35fe1cb5ad98 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -67,12 +67,9 @@ 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); @@ -200,6 +197,7 @@ 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); @@ -207,6 +205,8 @@ 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_add_cb(struct dma_resv *resv, bool write, @@ -259,6 +259,9 @@ 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_add_cb(resv, true, dcb)) /* No callback queued, wake up any other waiters */ dma_buf_poll_cb(NULL, &dcb->cb); @@ -279,6 +282,9 @@ 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_add_cb(resv, false, dcb)) /* No callback queued, wake up any other waiters */ dma_buf_poll_cb(NULL, &dcb->cb);