From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kolorific.com ([61.63.28.39]:52864 "EHLO mail.kolorific.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754287AbZERDxa (ORCPT ); Sun, 17 May 2009 23:53:30 -0400 Subject: Re: [PATCH]saa7134-video.c: poll method lose race condition From: "figo.zhang" To: hermann pitton Cc: Mauro Carvalho Chehab , g.liakhovetski@gmx.de, linux-media@vger.kernel.org, figo1802@126.com, kraxel@bytesex.org, Hans Verkuil In-Reply-To: <1242616075.3747.20.camel@pc07.localdom.local> References: <1242612794.3442.19.camel@myhost> <1242616075.3747.20.camel@pc07.localdom.local> Content-Type: text/plain Date: Mon, 18 May 2009 11:53:25 +0800 Message-Id: <1242618805.3442.45.camel@myhost> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On Mon, 2009-05-18 at 05:07 +0200, hermann pitton wrote: > Am Montag, den 18.05.2009, 10:13 +0800 schrieb figo.zhang: > > saa7134-video.c: poll method lose race condition > > > > > > Signed-off-by: Figo.zhang > > --- > > drivers/media/video/saa7134/saa7134-video.c | 9 ++++++--- > > 1 files changed, 6 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/media/video/saa7134/saa7134-video.c b/drivers/media/video/saa7134/saa7134-video.c > > index 493cad9..95733df 100644 > > --- a/drivers/media/video/saa7134/saa7134-video.c > > +++ b/drivers/media/video/saa7134/saa7134-video.c > > @@ -1423,11 +1423,13 @@ video_poll(struct file *file, struct poll_table_struct *wait) > > { > > struct saa7134_fh *fh = file->private_data; > > struct videobuf_buffer *buf = NULL; > > + unsigned int rc = 0; > > > > if (V4L2_BUF_TYPE_VBI_CAPTURE == fh->type) > > return videobuf_poll_stream(file, &fh->vbi, wait); > > > > if (res_check(fh,RESOURCE_VIDEO)) { > > + mutex_lock(&fh->cap.vb_lock); > > if (!list_empty(&fh->cap.stream)) > > buf = list_entry(fh->cap.stream.next, struct videobuf_buffer, stream); > > } else { > > @@ -1446,13 +1448,14 @@ video_poll(struct file *file, struct poll_table_struct *wait) > > } > > > > if (!buf) > > - return POLLERR; > > + rc = POLLERR; > > > > poll_wait(file, &buf->done, wait); > > if (buf->state == VIDEOBUF_DONE || > > buf->state == VIDEOBUF_ERROR) > > - return POLLIN|POLLRDNORM; > > - return 0; > > + rc = POLLIN|POLLRDNORM; > > + mutex_unlock(&fh->cap.vb_lock); > > + return rc; > > > > err: > > mutex_unlock(&fh->cap.vb_lock); > > > > > > Can you please give some description on what your patch might do > something? > > Or are you a robot? > > Then, please give us your serial number, production year, and when we > can expect you are out of duty and replaced ;) > > Cheers, > Hermann > > > hi, I just using the saa7134 chip to do a video capture card. The saa7134 driver in linux kernel, i found that the poll method have lose race condition for "RESOURCE_VIDEO". It have better to add a mutex lock.