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authorAndreas Schwab <schwab@suse.de>2020-05-07 15:50:09 +0200
committerAndreas Schwab <schwab@suse.de>2020-05-12 17:17:49 +0200
commit4cab20fa49b3ea3e3454fdc4f13bf3828d8efd19 (patch)
tree4d9e5f35863adc7468002bc246b2c4dbd0abfcd3 /nptl/pthread_create.c
parent16536e98e36e08bc1ce1edbd8dd50c7c3bb7a936 (diff)
downloadglibc-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.c11
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