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Tue, 08 Feb 2022 11:31:28 -0800 (PST) Message-ID: <77f7accd-3190-d454-0c72-bdf055895e3c@gmail.com> Date: Tue, 8 Feb 2022 16:31:26 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Content-Language: en-US To: ffmpeg-devel@ffmpeg.org References: <20220208182639.25696-1-anton@khirnov.net> <20220208182639.25696-2-anton@khirnov.net> From: James Almer In-Reply-To: <20220208182639.25696-2-anton@khirnov.net> Subject: Re: [FFmpeg-devel] [PATCH 2/2] lavu/hwcontext_qsv: fix a potential infinite loop 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 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 2/8/2022 3:26 PM, Anton Khirnov wrote: > Current code will loop forever if MFXVideoVPP_Init() fails. > Also, simplify the code. > --- > libavutil/hwcontext_qsv.c | 80 +++++++++++++++------------------------ > 1 file changed, 31 insertions(+), 49 deletions(-) > > diff --git a/libavutil/hwcontext_qsv.c b/libavutil/hwcontext_qsv.c > index d3d8f42c99..95f8071abe 100644 > --- a/libavutil/hwcontext_qsv.c > +++ b/libavutil/hwcontext_qsv.c > @@ -16,6 +16,7 @@ > * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA > */ > > +#include > #include > #include > > @@ -71,12 +72,11 @@ typedef struct QSVDeviceContext { > > typedef struct QSVFramesContext { > mfxSession session_download; > - int session_download_init; > + atomic_int session_download_init; > mfxSession session_upload; > - int session_upload_init; > + atomic_int session_upload_init; > #if HAVE_PTHREADS > pthread_mutex_t session_lock; > - pthread_cond_t session_cond; > #endif > > AVBufferRef *child_frames_ref; > @@ -297,7 +297,6 @@ static void qsv_frames_uninit(AVHWFramesContext *ctx) > > #if HAVE_PTHREADS > pthread_mutex_destroy(&s->session_lock); > - pthread_cond_destroy(&s->session_cond); > #endif > > av_freep(&s->mem_ids); > @@ -744,7 +743,6 @@ static int qsv_frames_init(AVHWFramesContext *ctx) > > #if HAVE_PTHREADS > pthread_mutex_init(&s->session_lock, NULL); > - pthread_cond_init(&s->session_cond, NULL); > #endif > > return 0; > @@ -1024,6 +1022,32 @@ static int map_frame_to_surface(const AVFrame *frame, mfxFrameSurface1 *surface) > return 0; > } > > +static int qsv_internal_session_check_init(AVHWFramesContext *ctx, int upload) > +{ > + QSVFramesContext *s = ctx->internal->priv; > + atomic_int *inited = upload ? &s->session_upload_init : &s->session_download_init; > + mfxSession *session = upload ? &s->session_upload : &s->session_download; > + int ret = 0; > + > + if (atomic_load(inited)) > + return 0; > + > +#if HAVE_PTHREADS > + pthread_mutex_lock(&s->session_lock); > +#endif > + > + if (!atomic_load(inited)) { > + ret = qsv_init_internal_session(ctx, session, upload); > + atomic_store(inited, 1); Nit: How about if (atomic_compare_exchange_strong(inited, &ret, 1)) ret = qsv_init_internal_session(ctx, session, upload); Or using some other variable for the second argument (It must be 0 before the call, and will become 1 if *inited was already 1). Since atomic_compare_exchange_strong() is not used anywhere in the tree, it would let us know if any of the atomics emulation implementations are faulty (win32, pthreads, old gcc). > + } > + > +#if HAVE_PTHREADS > + pthread_mutex_unlock(&s->session_lock); > +#endif > + > + return ret; > +} > + > static int qsv_transfer_data_from(AVHWFramesContext *ctx, AVFrame *dst, > const AVFrame *src) > { > @@ -1035,28 +1059,7 @@ static int qsv_transfer_data_from(AVHWFramesContext *ctx, AVFrame *dst, > mfxStatus err; > int ret = 0; > > - while (!s->session_download_init && !s->session_download && !ret) { > -#if HAVE_PTHREADS > - if (pthread_mutex_trylock(&s->session_lock) == 0) { > -#endif > - if (!s->session_download_init) { > - ret = qsv_init_internal_session(ctx, &s->session_download, 0); > - if (s->session_download) > - s->session_download_init = 1; > - } > -#if HAVE_PTHREADS > - pthread_mutex_unlock(&s->session_lock); > - pthread_cond_signal(&s->session_cond); > - } else { > - pthread_mutex_lock(&s->session_lock); > - while (!s->session_download_init && !s->session_download) { > - pthread_cond_wait(&s->session_cond, &s->session_lock); > - } > - pthread_mutex_unlock(&s->session_lock); > - } > -#endif > - } > - > + ret = qsv_internal_session_check_init(ctx, 0); > if (ret < 0) > return ret; > > @@ -1109,28 +1112,7 @@ static int qsv_transfer_data_to(AVHWFramesContext *ctx, AVFrame *dst, > const AVFrame *src_frame; > int realigned = 0; > > - > - while (!s->session_upload_init && !s->session_upload && !ret) { > -#if HAVE_PTHREADS > - if (pthread_mutex_trylock(&s->session_lock) == 0) { > -#endif > - if (!s->session_upload_init) { > - ret = qsv_init_internal_session(ctx, &s->session_upload, 1); > - if (s->session_upload) > - s->session_upload_init = 1; > - } > -#if HAVE_PTHREADS > - pthread_mutex_unlock(&s->session_lock); > - pthread_cond_signal(&s->session_cond); > - } else { > - pthread_mutex_lock(&s->session_lock); > - while (!s->session_upload_init && !s->session_upload) { > - pthread_cond_wait(&s->session_cond, &s->session_lock); > - } > - pthread_mutex_unlock(&s->session_lock); > - } > -#endif > - } > + ret = qsv_internal_session_check_init(ctx, 1); > if (ret < 0) > return ret; > _______________________________________________ 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".