AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-11-24 14:00:30 +00:00
Code Issues Packages Projects Releases Wiki Activity

nptl: Add one more barrier to nptl/tst-create1

Browse Source 
Without the bar_ctor_finish barrier, it was possible that thread2
re-locked user_lock before ctor had a chance to lock it.  ctor then
blocked in its locking operation, xdlopen from the main thread
did not return, and thread2 was stuck waiting in bar_dtor:

thread 1: started.
thread 2: started.
thread 2: locked user_lock.
constructor started: 0.
thread 1: in ctor: started.
thread 3: started.
thread 3: done.
thread 2: unlocked user_lock.
thread 2: locked user_lock.

Fixes the test in commit 83b5323261
("elf: Avoid deadlock between pthread_create and ctors [BZ #28357]").

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This commit is contained in:
Florian Weimer 2021-12-10 05:14:24 +01:00
parent 627f5ede70
commit 5cc3385654
1 changed files with 4 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
sysdeps/pthread/tst-create1.c
View File

@ -33,6 +33,7 @@ thread 2: lock(user_lock) -> pthread_create
*/
static pthread_barrier_t bar_ctor;
static pthread_barrier_t bar_ctor_finish;
static pthread_barrier_t bar_dtor;
static pthread_mutex_t user_lock = PTHREAD_MUTEX_INITIALIZER;
@ -46,6 +47,7 @@ ctor (void)
xpthread_mutex_unlock (&user_lock);
dprintf (1, "thread 1: in ctor: unlocked user_lock.\n");
dprintf (1, "thread 1: in ctor: done.\n");
xpthread_barrier_wait (&bar_ctor_finish);
}
void
@ -81,6 +83,7 @@ thread2 (void *a)
xpthread_mutex_unlock (&user_lock);
dprintf (1, "thread 2: unlocked user_lock.\n");
xpthread_join (t3);
xpthread_barrier_wait (&bar_ctor_finish);
xpthread_mutex_lock (&user_lock);
dprintf (1, "thread 2: locked user_lock.\n");
@ -99,6 +102,7 @@ thread1 (void)
{
dprintf (1, "thread 1: started.\n");
xpthread_barrier_init (&bar_ctor, NULL, 2);
xpthread_barrier_init (&bar_ctor_finish, NULL, 2);
xpthread_barrier_init (&bar_dtor, NULL, 2);
pthread_t t2 = xpthread_create (0, thread2, 0);
void *p = xdlopen ("tst-create1mod.so", RTLD_NOW | RTLD_GLOBAL);