53 lines
1.9 KiB
Diff
53 lines
1.9 KiB
Diff
From 4cab20fa49b3ea3e3454fdc4f13bf3828d8efd19 Mon Sep 17 00:00:00 2001
|
|
From: Andreas Schwab <schwab@suse.de>
|
|
Date: Thu, 7 May 2020 15:50:09 +0200
|
|
Subject: [PATCH] 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.
|
|
---
|
|
nptl/pthread_create.c | 11 ++++++-----
|
|
1 file 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
|
|
--
|
|
2.19.1
|
|
|