#include #include pthread_mutex_t a = PTHREAD_MUTEX_INITIALIZER; pthread_mutex_t b = PTHREAD_MUTEX_INITIALIZER; pthread_barrier_t bar; void *ba_lock(void *arg) { int ret, i; pthread_mutex_lock(&b); if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD) pthread_barrier_destroy(&bar); pthread_mutex_lock(&a); pthread_mutex_unlock(&a); pthread_mutex_unlock(&b); } int main(void) { pthread_t t; pthread_barrier_init(&bar, NULL, 2); if (pthread_create(&t, NULL, ba_lock, NULL)) { fprintf(stderr, "pthread_create() failed\n"); return 1; } pthread_mutex_lock(&a); if (pthread_barrier_wait(&bar) == PTHREAD_BARRIER_SERIAL_THREAD) pthread_barrier_destroy(&bar); pthread_mutex_lock(&b); pthread_mutex_unlock(&b); pthread_mutex_unlock(&a); pthread_join(t, NULL); return 0; } ss='form'>
net-next plumbingsTobias Klauser
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authorAndrei Vagin <avagin@openvz.org>2017-01-04 19:28:14 -0800
committerEric W. Biederman <ebiederm@xmission.com>2017-01-10 13:34:56 +1300
commitadd7c65ca426b7a37184dd3d2172394e23d585d6 (patch)
tree28b08b519540041b06ed0ab0b1c005076b932e8e /include/uapi/asm-generic/errno.h
parent75422726b0f717d67db3283c2eb5bc14fa2619c5 (diff)
pid: fix lockdep deadlock warning due to ucount_lock
========================================================= [ INFO: possible irq lock inversion dependency detected ] 4.10.0-rc2-00024-g4aecec9-dirty #118 Tainted: G W --------------------------------------------------------- swapper/1/0 just changed the state of lock: (&(&sighand->siglock)->rlock){-.....}, at: [<ffffffffbd0a1bc6>] __lock_task_sighand+0xb6/0x2c0 but this lock took another, HARDIRQ-unsafe lock in the past: (ucounts_lock){+.+...} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &(&sighand->siglock)->rlock --> &(&tty->ctrl_lock)->rlock --> ucounts_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(ucounts_lock); local_irq_disable(); lock(&(&sighand->siglock)->rlock); lock(&(&tty->ctrl_lock)->rlock); <Interrupt> lock(&(&sighand->siglock)->rlock); *** DEADLOCK *** This patch removes a dependency between rlock and ucount_lock. Fixes: f333c700c610 ("pidns: Add a limit on the number of pid namespaces") Cc: stable@vger.kernel.org Signed-off-by: Andrei Vagin <avagin@openvz.org> Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'include/uapi/asm-generic/errno.h')