Fixes:
https://fate.ffmpeg.org/report.cgi?slot=x86_64-archlinux-gcc-tsan&time=20240823175808
Reproduction steps:
./configure --enable-memory-poisoning --toolchain=gcc-tsan --disable-stripping
&& make fate-vvc
Root cause:
We hold the current frame's lock while updating progress for other frames.
This process also requires acquiring other frame locks. It could lead to a
deadlock.
Example scenario:
- Frame F0 holds mutex M0 and then tries to lock M1.
- Frame F1, meanwhile, holds mutex M1 and attempts to lock M0.
---
libavcodec/vvc/refs.c | 13 +++++++------
libavcodec/vvc/thread.c | 8 ++++++--
2 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/libavcodec/vvc/refs.c b/libavcodec/vvc/refs.c
index c1fc6132c2..bebcef7fd6 100644
--- a/libavcodec/vvc/refs.c
+++ b/libavcodec/vvc/refs.c
@@ -588,12 +588,13 @@ void ff_vvc_report_progress(VVCFrame *frame, const
VVCProgress vp, const int y)
VVCProgressListener *l = NULL;
ff_mutex_lock(&p->lock);
-
- av_assert0(p->progress[vp] < y || p->progress[vp] == INT_MAX);
- p->progress[vp] = y;
- l = get_done_listener(p, vp);
- ff_cond_signal(&p->cond);
-
+ if (p->progress[vp] < y) {
+ // Due to the nature of thread scheduling, later progress may reach
this point before earlier progress.
+ // Therefore, we only update the progress when p->progress[vp] < y.
+ p->progress[vp] = y;
+ l = get_done_listener(p, vp);
+ ff_cond_signal(&p->cond);
+ }
ff_mutex_unlock(&p->lock);
while (l) {
diff --git a/libavcodec/vvc/thread.c b/libavcodec/vvc/thread.c
index 74f8e4e9d0..86a7753c6a 100644
--- a/libavcodec/vvc/thread.c
+++ b/libavcodec/vvc/thread.c
@@ -466,12 +466,16 @@ static void report_frame_progress(VVCFrameContext *fc,
y = old = ft->row_progress[idx];
while (y < ft->ctu_height &&
atomic_load(&ft->rows[y].col_progress[idx]) == ft->ctu_width)
y++;
+ if (old != y)
+ ft->row_progress[idx] = y;
+ // ff_vvc_report_progress will acquire other frames' locks, which
could lead to a deadlock
+ // We need to unlock ft->lock first
+ ff_mutex_unlock(&ft->lock);
+
if (old != y) {
const int progress = y == ft->ctu_height ? INT_MAX : y * ctu_size;
- ft->row_progress[idx] = y;
ff_vvc_report_progress(fc->ref, idx, progress);
}
- ff_mutex_unlock(&ft->lock);
}
}
--
2.34.1
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