[FFmpeg-devel] [PATCH 1/2] error_resilience: remove avpriv_atomic usage

[Michael Niedermayer]

On Fri, Nov 24, 2017 at 10:18:06PM -0300, James Almer wrote:
> On 11/24/2017 9:33 PM, Rostislav Pehlivanov wrote:
> > Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>
> > ---
> >  libavcodec/error_resilience.c | 12 ++++++------
> >  libavcodec/error_resilience.h |  3 ++-
> >  2 files changed, 8 insertions(+), 7 deletions(-)
> > 
> > diff --git a/libavcodec/error_resilience.c b/libavcodec/error_resilience.c
> > index 0c7f29d171..6c7b4207af 100644
> > --- a/libavcodec/error_resilience.c
> > +++ b/libavcodec/error_resilience.c
> > @@ -852,20 +852,20 @@ void ff_er_add_slice(ERContext *s, int startx, int starty,
> >      mask &= ~VP_START;
> >      if (status & (ER_AC_ERROR | ER_AC_END)) {
> >          mask           &= ~(ER_AC_ERROR | ER_AC_END);
> > -        avpriv_atomic_int_add_and_fetch(&s->error_count, start_i - end_i - 1);
> > +        atomic_fetch_add(&s->error_count, start_i - end_i - 1);
> >      }
> >      if (status & (ER_DC_ERROR | ER_DC_END)) {
> >          mask           &= ~(ER_DC_ERROR | ER_DC_END);
> > -        avpriv_atomic_int_add_and_fetch(&s->error_count, start_i - end_i - 1);
> > +        atomic_fetch_add(&s->error_count, start_i - end_i - 1);
> >      }
> >      if (status & (ER_MV_ERROR | ER_MV_END)) {
> >          mask           &= ~(ER_MV_ERROR | ER_MV_END);
> > -        avpriv_atomic_int_add_and_fetch(&s->error_count, start_i - end_i - 1);
> > +        atomic_fetch_add(&s->error_count, start_i - end_i - 1);
> >      }
> >  
> >      if (status & ER_MB_ERROR) {
> >          s->error_occurred = 1;
> > -        avpriv_atomic_int_set(&s->error_count, INT_MAX);
> > +        atomic_store(&s->error_count, INT_MAX);
> >      }
> >  
> >      if (mask == ~0x7F) {
> > @@ -878,7 +878,7 @@ void ff_er_add_slice(ERContext *s, int startx, int starty,
> >      }
> >  
> >      if (end_i == s->mb_num)
> > -        avpriv_atomic_int_set(&s->error_count, INT_MAX);
> > +        atomic_store(&s->error_count, INT_MAX);
> >      else {
> >          s->error_status_table[end_xy] &= mask;
> >          s->error_status_table[end_xy] |= status;
> > @@ -893,7 +893,7 @@ void ff_er_add_slice(ERContext *s, int startx, int starty,
> >          prev_status &= ~ VP_START;
> >          if (prev_status != (ER_MV_END | ER_DC_END | ER_AC_END)) {
> >              s->error_occurred = 1;
> > -            avpriv_atomic_int_set(&s->error_count, INT_MAX);
> > +            atomic_store(&s->error_count, INT_MAX);
> >          }
> >      }
> >  }
> > diff --git a/libavcodec/error_resilience.h b/libavcodec/error_resilience.h
> > index 27c2008694..664a765659 100644
> > --- a/libavcodec/error_resilience.h
> > +++ b/libavcodec/error_resilience.h
> > @@ -20,6 +20,7 @@
> >  #define AVCODEC_ERROR_RESILIENCE_H
> >  
> >  #include <stdint.h>
> > +#include <stdatomic.h>
> >  
> >  #include "avcodec.h"
> >  #include "me_cmp.h"
> > @@ -60,7 +61,7 @@ typedef struct ERContext {
> >      ptrdiff_t mb_stride;
> >      ptrdiff_t b8_stride;
> >  
> > -    volatile int error_count;
> > +    atomic_int error_count;
> >      int error_occurred;
> >      uint8_t *error_status_table;
> >      uint8_t *er_temp_buffer;
> > 
> 
> This is missing the initialization of error_count in ff_er_frame_start().
> 
> I'm not sure if you can use atomic_init() there or should instead use
> atomic_store(), as the former is supposedly not thread safe and i don't
> know how and when ff_er_frame_start() is called.

the frame start / end stuff should not run in paralell with anything
else from the current frame

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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