From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758062AbYEQTfW (ORCPT ); Sat, 17 May 2008 15:35:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751512AbYEQTfJ (ORCPT ); Sat, 17 May 2008 15:35:09 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:52486 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755013AbYEQTfI (ORCPT ); Sat, 17 May 2008 15:35:08 -0400 Date: Sat, 17 May 2008 12:34:52 -0700 From: Arjan van de Ven To: Arjan van de Ven Cc: "koos vriezen" , linux-kernel@vger.kernel.org, mchehab@infradead.org Subject: Re: mplayer v4l hangs in 2.6.25.2/4 (likely regression) Message-ID: <20080517123452.79b82be2@infradead.org> In-Reply-To: <20080517122640.2d15aeed@infradead.org> References: <20080517111639.21a3e177@infradead.org> <20080517122640.2d15aeed@infradead.org> Organization: Intel X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.9; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org and here is an (untest) patch that should fix this problem: Koos, can you apply this to your kernel tree and report back if this fixes your deadlock? From: Arjan van de Ven Subject: [PATCH] Fix a deadlock in the bttv driver vidiocgmbuf() does this: mutex_lock(&fh->cap.vb_lock); retval = videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize, V4L2_MEMORY_MMAP); and videobuf_mmap_setup() then just does mutex_lock(&q->vb_lock); ret = __videobuf_mmap_setup(q, bcount, bsize, memory); mutex_unlock(&q->vb_lock); which is an obvious double-take deadlock. This patch fixes this by having vidiocgmbuf() just call the __videobuf_mmap_setup function instead. Reported-by: Koos Vriezen Signed-off-by: Arjan van de Ven --- drivers/media/video/bt8xx/bttv-driver.c | 2 +- drivers/media/video/videobuf-core.c | 3 ++- include/media/videobuf-core.h | 3 +++ 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/media/video/bt8xx/bttv-driver.c b/drivers/media/video/bt8xx/bttv-driver.c index 2ca3e9c..0165aac 100644 --- a/drivers/media/video/bt8xx/bttv-driver.c +++ b/drivers/media/video/bt8xx/bttv-driver.c @@ -2613,7 +2613,7 @@ static int vidiocgmbuf(struct file *file, void *priv, struct video_mbuf *mbuf) struct bttv_fh *fh = priv; mutex_lock(&fh->cap.vb_lock); - retval = videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize, + retval = __videobuf_mmap_setup(&fh->cap, gbuffers, gbufsize, V4L2_MEMORY_MMAP); if (retval < 0) { mutex_unlock(&fh->cap.vb_lock); diff --git a/drivers/media/video/videobuf-core.c b/drivers/media/video/videobuf-core.c index 982f446..0a88c44 100644 --- a/drivers/media/video/videobuf-core.c +++ b/drivers/media/video/videobuf-core.c @@ -331,7 +331,7 @@ int videobuf_mmap_free(struct videobuf_queue *q) } /* Locking: Caller holds q->vb_lock */ -static int __videobuf_mmap_setup(struct videobuf_queue *q, +int __videobuf_mmap_setup(struct videobuf_queue *q, unsigned int bcount, unsigned int bsize, enum v4l2_memory memory) { @@ -1129,6 +1129,7 @@ EXPORT_SYMBOL_GPL(videobuf_read_stream); EXPORT_SYMBOL_GPL(videobuf_read_one); EXPORT_SYMBOL_GPL(videobuf_poll_stream); +EXPORT_SYMBOL_GPL(__videobuf_mmap_setup); EXPORT_SYMBOL_GPL(videobuf_mmap_setup); EXPORT_SYMBOL_GPL(videobuf_mmap_free); EXPORT_SYMBOL_GPL(videobuf_mmap_mapper); diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h index 5b39a22..874f134 100644 --- a/include/media/videobuf-core.h +++ b/include/media/videobuf-core.h @@ -237,6 +237,9 @@ unsigned int videobuf_poll_stream(struct file *file, int videobuf_mmap_setup(struct videobuf_queue *q, unsigned int bcount, unsigned int bsize, enum v4l2_memory memory); +int __videobuf_mmap_setup(struct videobuf_queue *q, + unsigned int bcount, unsigned int bsize, + enum v4l2_memory memory); int videobuf_mmap_free(struct videobuf_queue *q); int videobuf_mmap_mapper(struct videobuf_queue *q, struct vm_area_struct *vma); -- 1.5.4.5