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| author | Rich Felker <dalias@aerifal.cx> | 2020-11-20 10:43:20 -0500 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2020-11-20 10:43:20 -0500 |
| commit | debbddf7c86dfe7fb2f44f057123ccfd950ff555 (patch) | |
| tree | bfb268bc3a66503da366658c2f9ef6d0c86b6ebd | |
| parent | 3ab2a4e02682df1382955071919d8aa3c3ec40d4 (diff) | |
| download | musl-debbddf7c86dfe7fb2f44f057123ccfd950ff555.tar.gz musl-debbddf7c86dfe7fb2f44f057123ccfd950ff555.tar.xz musl-debbddf7c86dfe7fb2f44f057123ccfd950ff555.zip | |
fix regression in pthread_exit
commit d26e0774a59bb7245b205bc8e7d8b35cc2037095 moved the detach state transition at exit before the thread list lock was taken. this inadvertently allowed pthread_join to race to take the thread list lock first, and proceed with unmapping of the exiting thread's memory. we could fix this by just revering the offending commit and instead performing __vm_wait unconditionally before taking the thread list lock, but that may be costly. instead, bring back the old DT_EXITING vs DT_EXITED state distinction that was removed in commit 8f11e6127fe93093f81a52b15bb1537edc3fc8af, and don't transition to DT_EXITED (a value of 0, which is what pthread_join waits for) until after the lock has been taken.
| -rw-r--r-- | src/internal/pthread_impl.h | 3 | ||||
| -rw-r--r-- | src/thread/pthread_create.c | 1 |
2 files changed, 3 insertions, 1 deletions
diff --git a/src/internal/pthread_impl.h b/src/internal/pthread_impl.h index 1322a6a8..de2b9d8b 100644 --- a/src/internal/pthread_impl.h +++ b/src/internal/pthread_impl.h @@ -68,7 +68,8 @@ struct pthread { }; enum { - DT_EXITING = 0, + DT_EXITED = 0, + DT_EXITING, DT_JOINABLE, DT_DETACHED, }; diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c index 250cd0a4..6f187ee8 100644 --- a/src/thread/pthread_create.c +++ b/src/thread/pthread_create.c @@ -156,6 +156,7 @@ _Noreturn void __pthread_exit(void *result) } /* Wake any joiner. */ + a_store(&self->detach_state, DT_EXITED); __wake(&self->detach_state, 1, 1); /* After the kernel thread exits, its tid may be reused. Clear it |