From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 295C0468A1 for ; Sun, 23 Jul 2023 08:19:00 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5E35768C67D; Sun, 23 Jul 2023 11:18:57 +0300 (EEST) Received: from iq.passwd.hu (iq.passwd.hu [217.27.212.140]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 3840A68C2D7 for ; Sun, 23 Jul 2023 11:18:51 +0300 (EEST) Received: from localhost (localhost [127.0.0.1]) by iq.passwd.hu (Postfix) with ESMTP id EFF03E919D; Sun, 23 Jul 2023 10:15:52 +0200 (CEST) X-Virus-Scanned: amavisd-new at passwd.hu Received: from iq.passwd.hu ([127.0.0.1]) by localhost (iq.passwd.hu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DvNEoqDqjMPC; Sun, 23 Jul 2023 10:15:50 +0200 (CEST) Received: from iq (iq [217.27.212.140]) by iq.passwd.hu (Postfix) with ESMTPS id 4705BE8F55; Sun, 23 Jul 2023 10:15:50 +0200 (CEST) Date: Sun, 23 Jul 2023 10:15:50 +0200 (CEST) From: Marton Balint To: FFmpeg development discussions and patches In-Reply-To: Message-ID: <87aa211d-9bc3-451a-748f-c119a548fc73@passwd.hu> References: <20230718220017.3336-1-mailingradian@gmail.com> MIME-Version: 1.0 Subject: Re: [FFmpeg-devel] [RESEND PATCH] avcodec/v4l2_context: always log POLLERR when buffers are uninitialized X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Cc: Richard Acayan Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On Fri, 21 Jul 2023, Richard Acayan wrote: > Will this patch be applied or receive any comments? I have been waiting > more than 2 weeks since the original submission > (https://ffmpeg.org/pipermail/ffmpeg-devel/2023-July/311580.html) and > have not received a response since. > > I am trying to get mpv to work again with the v4l2_m2m codec, as it > started emitting segmentation faults. This is partly due to some > incorrect usage of libavcodec in mpv, and partly due to the > error/warning handling in libavcodec. An mpv maintainer dismissed this > as a bug in ffmpeg, and this change is simpler than what mpv would need > for a fix, so I am hoping that this patch goes in. > > I don't have write access so I can't apply it myself, even if there are > no objections. > > On Tue, Jul 18, 2023 at 06:00:17PM -0400, Richard Acayan wrote: >> The error handler for POLLERRs assumes that the timeout is only zero >> when v4l2_dequeue_v4l2buf is called by v4l2_getfree_v4l2buf. This >> assumption is incorrect, as ff_v4l2_context_dequeue_frame also calls >> this function with a timeout of zero. Do not check for unavailable >> buffers if the buffers are uninitialized. >> >> See https://trac.ffmpeg.org/ticket/9957 for the original bug report. >> >> Signed-off-by: Richard Acayan >> --- >> libavcodec/v4l2_context.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c >> index a40be94690..69ddf80723 100644 >> --- a/libavcodec/v4l2_context.c >> +++ b/libavcodec/v4l2_context.c >> @@ -327,7 +327,7 @@ start: >> if (pfd.revents & POLLERR) { >> /* if we are trying to get free buffers but none have been queued yet >> no need to raise a warning */ >> - if (timeout == 0) { >> + if (timeout == 0 && ctx->buffers) { This would warn if no buffers are allocated yet, but this is not a warning condition as far as I understand the issue, simply a different API usage pattern. So maybe it is better to simply do a if (!ctx->buffers) return NULL; in the beginning of the if (timeout == 0) block. Thanks, Marton >> for (i = 0; i < ctx->num_buffers; i++) { >> if (ctx->buffers[i].status != V4L2BUF_AVAILABLE) >> av_log(logger(ctx), AV_LOG_WARNING, "%s POLLERR\n", ctx->name); >> -- >> 2.41.0 >> > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".