CVSROOT: /cvs/dm Module name: multipath-tools Branch: RHEL5_FC6 Changes by: bmarzins@xxxxxxxxxxxxxx 2008-08-27 19:14:58 Modified files: libmultipath : lock.c lock.h log_pthread.c waiter.c multipathd : main.c Log message: Fix a multipathd signal deadlock. If multipathd is run with -v3, both the SIGHUP, and the SIGUSR1 signal handlers will log a message. If a multipathd thread receives one of these signals while it has a log lock held, it deadlocks itself. Also, the SIGHUP handler will grab the vecs lock, so if any thread receives a SIGHUP while holding the vecs lock, it deadlocks itself. This commit blocks the appropriate signals to guard against this. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/multipath-tools/libmultipath/lock.c.diff?cvsroot=dm&only_with_tag=RHEL5_FC6&r1=1.1&r2=1.1.2.1 http://sourceware.org/cgi-bin/cvsweb.cgi/multipath-tools/libmultipath/lock.h.diff?cvsroot=dm&only_with_tag=RHEL5_FC6&r1=1.1&r2=1.1.2.1 http://sourceware.org/cgi-bin/cvsweb.cgi/multipath-tools/libmultipath/log_pthread.c.diff?cvsroot=dm&only_with_tag=RHEL5_FC6&r1=1.1.2.1&r2=1.1.2.2 http://sourceware.org/cgi-bin/cvsweb.cgi/multipath-tools/libmultipath/waiter.c.diff?cvsroot=dm&only_with_tag=RHEL5_FC6&r1=1.1.2.1&r2=1.1.2.2 http://sourceware.org/cgi-bin/cvsweb.cgi/multipath-tools/multipathd/main.c.diff?cvsroot=dm&only_with_tag=RHEL5_FC6&r1=1.69.2.7&r2=1.69.2.8 --- multipath-tools/libmultipath/lock.c 2006/06/06 18:46:38 1.1 +++ multipath-tools/libmultipath/lock.c 2008/08/27 19:14:57 1.1.2.1 @@ -1,6 +1,15 @@ #include <pthread.h> +#include <signal.h> #include "lock.h" +void block_signal(int signum, sigset_t *old) +{ + sigset_t set; + sigemptyset(&set); + sigaddset(&set, signum); + pthread_sigmask(SIG_BLOCK, &set, old); +} + void cleanup_lock (void * data) { unlock((pthread_mutex_t *)data); --- multipath-tools/libmultipath/lock.h 2006/06/06 18:46:38 1.1 +++ multipath-tools/libmultipath/lock.h 2008/08/27 19:14:57 1.1.2.1 @@ -1,6 +1,8 @@ #ifndef _LOCK_H #define _LOCK_H +#include <signal.h> + #ifdef LCKDBG #define lock(a) \ fprintf(stderr, "%s:%s(%i) lock %p\n", __FILE__, __FUNCTION__, __LINE__, a); \ @@ -18,5 +20,6 @@ #endif void cleanup_lock (void * data); +void block_signal(int signum, sigset_t *old); #endif /* _LOCK_H */ --- multipath-tools/libmultipath/log_pthread.c 2007/06/15 19:03:02 1.1.2.1 +++ multipath-tools/libmultipath/log_pthread.c 2008/08/27 19:14:57 1.1.2.2 @@ -11,9 +11,15 @@ #include "log_pthread.h" #include "log.h" +#include "lock.h" void log_safe (int prio, const char * fmt, va_list ap) { + sigset_t old; + + block_signal(SIGUSR1, &old); + block_signal(SIGHUP, NULL); + pthread_mutex_lock(logq_lock); //va_start(ap, fmt); log_enqueue(prio, fmt, ap); @@ -23,6 +29,8 @@ pthread_mutex_lock(logev_lock); pthread_cond_signal(logev_cond); pthread_mutex_unlock(logev_lock); + + pthread_sigmask(SIG_SETMASK, &old, NULL); } static void flush_logqueue (void) --- multipath-tools/libmultipath/waiter.c 2007/06/15 19:03:02 1.1.2.1 +++ multipath-tools/libmultipath/waiter.c 2008/08/27 19:14:57 1.1.2.2 @@ -32,11 +32,13 @@ void free_waiter (void *data) { + sigset_t old; struct event_thread *wp = (struct event_thread *)data; /* * indicate in mpp that the wp is already freed storage */ + block_signal(SIGHUP, &old); lock(wp->vecs->lock); if (wp->mpp) @@ -48,6 +50,7 @@ condlog(3, "free_waiter, mpp freed before wp=%p,", wp); unlock(wp->vecs->lock); + pthread_sigmask(SIG_SETMASK, &old, NULL); if (wp->dmt) dm_task_destroy(wp->dmt); --- multipath-tools/multipathd/main.c 2008/05/12 18:48:03 1.69.2.7 +++ multipath-tools/multipathd/main.c 2008/08/27 19:14:58 1.69.2.8 @@ -705,6 +705,9 @@ static void * ueventloop (void * ap) { + block_signal(SIGUSR1, NULL); + block_signal(SIGHUP, NULL); + if (uevent_listen(&uev_trigger, ap)) fprintf(stderr, "error starting uevent listener"); @@ -720,6 +723,9 @@ if (alloc_handlers()) return NULL; + block_signal(SIGUSR1, NULL); + block_signal(SIGHUP, NULL); + add_handler(LIST+PATHS, cli_list_paths); add_handler(LIST+MAPS, cli_list_maps); add_handler(LIST+MAPS+STATUS, cli_list_maps_status); @@ -880,6 +886,7 @@ int count = 0; int newstate; unsigned int i; + sigset_t old; mlockall(MCL_CURRENT | MCL_FUTURE); vecs = (struct vectors *)ap; @@ -893,6 +900,7 @@ } while (1) { + block_signal(SIGHUP, &old); pthread_cleanup_push(cleanup_lock, vecs->lock); lock(vecs->lock); condlog(4, "tick"); @@ -1051,6 +1059,7 @@ } lock_cleanup_pop(vecs->lock); + pthread_sigmask(SIG_SETMASK, &old, NULL); sleep(1); } return NULL; @@ -1532,6 +1541,7 @@ /* * exit path */ + block_signal(SIGHUP, NULL); lock(vecs->lock); remove_maps(vecs, stop_waiter_thread); free_pathvec(vecs->pathvec, FREE_PATHS); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
