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Fix deadlock in case of evconnlistener_disable() in parallel with callback
I've got an issue when stop evconnlistener not in the event_base_loop()
thread. evconnlistener_disable() acquired lev->lock, if the same time,
user callbacks is runing, the event thread released lock, after callback
finished, it try to aquire the lock again, I think this makes conflict:
Here is backtraces:
thread 1:
0 __lll_lock_wait (futex=futex@entry=0x555555559a60, private=0) at lowlevellock.c:52
1 0x00007ffff7f2a131 in __GI___pthread_mutex_lock (mutex=0x555555559a60) at ../nptl/pthread_mutex_lock.c:115
2 0x00007ffff7f424c9 in evthread_posix_lock (mode=0, lock_=0x555555559a60) at evthread_pthread.c:79
3 0x00007ffff7f7dc12 in listener_read_cb (fd=7, what=2, p=0x5555555599a0) at listener.c:439
4 0x00007ffff7f6d758 in event_persist_closure (base=0x555555559370, ev=0x5555555599d8) at event.c:1645
5 0x00007ffff7f6da60 in event_process_active_single_queue (base=0x555555559370, activeq=0x5555555597e0,
max_to_process=2147483647, endtime=0x0) at event.c:1704
6 0x00007ffff7f6e018 in event_process_active (base=0x555555559370) at event.c:1805
7 0x00007ffff7f6e92a in event_base_loop (base=0x555555559370, flags=0) at event.c:2047
8 0x0000555555555449 in main () at test_listen.c:67
thread 2:
0 futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555555559858) at ../sysdeps/nptl/futex-internal.h:183
1 __pthread_cond_wait_common (abstime=0x0, clockid=0, mutex=0x555555559800, cond=0x555555559830) at pthread_cond_wait.c:508
2 __pthread_cond_wait (cond=0x555555559830, mutex=0x555555559800) at pthread_cond_wait.c:638
3 0x00007ffff7f426f3 in evthread_posix_cond_wait (cond_=0x555555559830, lock_=0x555555559800, tv=0x0) at evthread_pthread.c:162
4 0x00007ffff7f70bc5 in event_del_nolock_ (ev=0x5555555599d8, blocking=2) at event.c:2934
5 0x00007ffff7f70748 in event_del_ (ev=0x5555555599d8, blocking=2) at event.c:2821
6 0x00007ffff7f707a1 in event_del (ev=0x5555555599d8) at event.c:2830
7 0x00007ffff7f7d76e in event_listener_disable (lev=0x5555555599a0) at listener.c:343
8 0x00007ffff7f7d6e5 in evconnlistener_disable (lev=0x5555555599a0) at listener.c:325
9 0x00005555555552c3 in disable_thread (arg=0x5555555599a0) at test_listen.c:27
10 0x00007ffff7f27609 in start_thread (arg=<optimized out>) at pthread_create.c:477
11 0x00007ffff7e4e293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
This commit is contained in:
moonlightsh
Azat Khuzhin
parent
e1ecc6fa0d
commit
12cedc8a4f
@ -433,10 +433,8 @@ listener_read_cb(evutil_socket_t fd, short what, void *p)
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++lev->refcnt;
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cb = lev->cb;
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user_data = lev->user_data;
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UNLOCK(lev);
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cb(lev, new_fd, (struct sockaddr*)&ss, (int)socklen,
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user_data);
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LOCK(lev);
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if (lev->refcnt == 1) {
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int freed = listener_decref_and_unlock(lev);
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EVUTIL_ASSERT(freed);
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@ -458,9 +456,7 @@ listener_read_cb(evutil_socket_t fd, short what, void *p)
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++lev->refcnt;
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errorcb = lev->errorcb;
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user_data = lev->user_data;
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UNLOCK(lev);
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errorcb(lev, user_data);
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LOCK(lev);
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listener_decref_and_unlock(lev);
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} else {
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event_sock_warn(fd, "Error from accept() call");
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@ -49,6 +49,11 @@
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#include "event2/listener.h"
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#include "event2/event.h"
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#include "event2/util.h"
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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#include "event2/thread.h"
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#include "regress_thread.h"
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#endif
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#include "regress.h"
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#include "tinytest.h"
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@ -304,6 +309,127 @@ end:
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}
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#endif
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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static THREAD_FN
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disable_thread(void * arg)
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{
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struct evconnlistener *lev = (struct evconnlistener *)arg;
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evconnlistener_disable(lev);
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return NULL;
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}
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static void
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acceptcb_for_thread_test(struct evconnlistener *listener, evutil_socket_t fd,
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struct sockaddr *addr, int socklen, void *arg)
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{
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THREAD_T *threadid_arg;
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THREAD_T threadid;
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struct timeval delay = { .tv_sec = 0, .tv_usec = 5000 };
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threadid_arg = (THREAD_T *)arg;
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evutil_closesocket(fd);
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/* We need to run evconnlistener_disable() from disable_thread
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* in parallel with processing this callback to trigger deadlock regression
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*/
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THREAD_START(threadid, disable_thread, listener);
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evutil_usleep_(&delay);
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*threadid_arg = threadid;
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}
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static void
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regress_listener_disable_in_thread(void *arg)
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{
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struct basic_test_data *data = arg;
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struct event_base *base = data->base;
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struct evconnlistener *listener = NULL;
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struct sockaddr_in sin;
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struct sockaddr_storage ss;
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ev_socklen_t slen = sizeof(ss);
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evutil_socket_t fd = EVUTIL_INVALID_SOCKET;
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unsigned int flags = LEV_OPT_CLOSE_ON_FREE|LEV_OPT_REUSEABLE|LEV_OPT_THREADSAFE;
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THREAD_T threadid;
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memset(&sin, 0, sizeof(sin));
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sin.sin_family = AF_INET;
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sin.sin_addr.s_addr = htonl(0x7f000001); /* 127.0.0.1 */
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sin.sin_port = 0; /* "You pick!" */
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listener = evconnlistener_new_bind(base, acceptcb_for_thread_test, (void*)(&threadid),
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flags, -1, (struct sockaddr *)&sin, sizeof(sin));
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tt_assert(listener);
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tt_assert(getsockname(evconnlistener_get_fd(listener),
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(struct sockaddr*)&ss, &slen) == 0);
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tt_assert(evutil_socket_connect_(&fd, (struct sockaddr*)&ss, slen) != -1);
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event_base_loop(base, EVLOOP_ONCE);
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THREAD_JOIN(threadid);
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end:
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if (listener)
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evconnlistener_free(listener);
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}
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static void
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errorcb_for_thread_test(struct evconnlistener *listener, void *arg)
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{
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THREAD_T *threadid_arg;
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THREAD_T threadid;
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struct timeval delay = { .tv_sec = 0, .tv_usec = 5000 };
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threadid_arg = (THREAD_T *)arg;
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/* We need to run evconnlistener_disable() from disable_thread
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* in parallel with processing this callback to trigger deadlock regression
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*/
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THREAD_START(threadid, disable_thread, listener);
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evutil_usleep_(&delay);
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*threadid_arg = threadid;
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}
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static void
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acceptcb_for_thread_test_error(struct evconnlistener *listener, evutil_socket_t fd,
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struct sockaddr *addr, int socklen, void *arg)
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{
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}
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static void
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regress_listener_disable_in_thread_error(void *arg)
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{
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struct basic_test_data *data = arg;
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struct event_base *base = data->base;
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struct evconnlistener *listener = NULL;
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unsigned int flags = LEV_OPT_CLOSE_ON_FREE|LEV_OPT_REUSEABLE|LEV_OPT_THREADSAFE;
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THREAD_T threadid;
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/* send, so that pair[0] will look 'readable'*/
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tt_int_op(send(data->pair[1], "hello", 5, 0), >, 0);
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/* Start a listener with a bogus socket. */
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listener = evconnlistener_new(base, acceptcb_for_thread_test_error, (void*)&threadid,
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flags, 0,
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data->pair[0]);
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tt_assert(listener);
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evconnlistener_set_error_cb(listener, errorcb_for_thread_test);
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event_base_loop(base, EVLOOP_ONCE);
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THREAD_JOIN(threadid);
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end:
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if (listener)
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evconnlistener_free(listener);
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}
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#endif
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struct testcase_t listener_testcases[] = {
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{ "randport", regress_pick_a_port, TT_FORK|TT_NEED_BASE,
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@ -332,6 +458,16 @@ struct testcase_t listener_testcases[] = {
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{ "immediate_close", regress_listener_immediate_close,
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TT_FORK|TT_NEED_BASE, &basic_setup, NULL, },
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#ifndef EVENT__DISABLE_THREAD_SUPPORT
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{ "disable_in_thread", regress_listener_disable_in_thread,
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TT_FORK|TT_NEED_BASE|TT_NEED_THREADS,
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&basic_setup, NULL, },
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{ "disable_in_thread_error", regress_listener_disable_in_thread_error,
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TT_FORK|TT_NEED_BASE|TT_NEED_THREADS|TT_NEED_SOCKETPAIR,
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&basic_setup, NULL, },
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#endif
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END_OF_TESTCASES,
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};
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