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| author | Andreas Schwab <schwab@suse.de> | 2020-05-07 15:50:09 +0200 |
|---|---|---|
| committer | Andreas Schwab <schwab@suse.de> | 2020-05-12 17:17:49 +0200 |
| commit | 4cab20fa49b3ea3e3454fdc4f13bf3828d8efd19 (patch) | |
| tree | 4d9e5f35863adc7468002bc246b2c4dbd0abfcd3 /nptl/pthread_create.c | |
| parent | 16536e98e36e08bc1ce1edbd8dd50c7c3bb7a936 (diff) | |
| download | glibc-4cab20fa49b3ea3e3454fdc4f13bf3828d8efd19.tar.gz | |
nptl: wait for pending setxid request also in detached thread (bug 25942)
There is a race between __nptl_setxid and exiting detached thread, which
causes a deadlock on stack_cache_lock. The deadlock happens in this
state:
T1: setgroups -> __nptl_setxid (holding stack_cache_lock, waiting on cmdp->cntr == 0)
T2 (detached, exiting): start_thread -> __deallocate_stack (waiting on stack_cache_lock)
more threads waiting on stack_cache_lock in pthread_create
For non-detached threads, start_thread waits for its own setxid handler to
finish before exiting. Do this for detached threads as well.
Diffstat (limited to 'nptl/pthread_create.c')
| -rw-r--r-- | nptl/pthread_create.c | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c index afd379e89a..a43089065c 100644 --- a/nptl/pthread_create.c +++ b/nptl/pthread_create.c @@ -552,11 +552,7 @@ START_THREAD_DEFN advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd, pd->guardsize); - /* If the thread is detached free the TCB. */ - if (IS_DETACHED (pd)) - /* Free the TCB. */ - __free_tcb (pd); - else if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK)) + if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK)) { /* Some other thread might call any of the setXid functions and expect us to reply. In this case wait until we did that. */ @@ -572,6 +568,11 @@ START_THREAD_DEFN pd->setxid_futex = 0; } + /* If the thread is detached free the TCB. */ + if (IS_DETACHED (pd)) + /* Free the TCB. */ + __free_tcb (pd); + /* We cannot call '_exit' here. '_exit' will terminate the process. The 'exit' implementation in the kernel will signal when the |