From mboxrd@z Thu Jan 1 00:00:00 1970 From: zkabelac@sourceware.org Date: 11 Oct 2011 09:26:04 -0000 Subject: LVM2 ./WHATS_NEW daemons/clvmd/clvmd.c Message-ID: <20111011092604.10366.qmail@sourceware.org> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: zkabelac at sourceware.org 2011-10-11 09:26:04 Modified files: . : WHATS_NEW daemons/clvmd : clvmd.c Log message: Use barrier instead of mutex Barrier is supposed to be used in situation like this and replace tricky mutex usage, where mutex has been unlocked by a different thread than the locking thread. Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/WHATS_NEW.diff?cvsroot=lvm2&r1=1.2158&r2=1.2159 http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/daemons/clvmd/clvmd.c.diff?cvsroot=lvm2&r1=1.112&r2=1.113 --- LVM2/WHATS_NEW 2011/10/11 09:20:17 1.2158 +++ LVM2/WHATS_NEW 2011/10/11 09:26:04 1.2159 @@ -1,5 +1,6 @@ Version 2.02.89 - ================================== + Use pthread_barrier to synchronize clvmd threads at startup. Limit clvmd's thread size to 128KiB. Reduce default preallocated stack size to 64KiB. Add check for access through NULL pointer when refresh_filter() fails. --- LVM2/daemons/clvmd/clvmd.c 2011/10/11 09:23:48 1.112 +++ LVM2/daemons/clvmd/clvmd.c 2011/10/11 09:26:04 1.113 @@ -89,7 +89,7 @@ static pthread_attr_t stack_attr; static pthread_mutex_t lvm_thread_mutex; static pthread_cond_t lvm_thread_cond; -static pthread_mutex_t lvm_start_mutex; +static pthread_barrier_t lvm_start_barrier; static struct dm_list lvm_cmd_head; static volatile sig_atomic_t quit = 0; static volatile sig_atomic_t reread_config = 0; @@ -505,7 +505,7 @@ } pthread_mutex_init(&lvm_thread_mutex, NULL); pthread_cond_init(&lvm_thread_cond, NULL); - pthread_mutex_init(&lvm_start_mutex, NULL); + pthread_barrier_init(&lvm_start_barrier, NULL, 2); init_lvhash(); /* Start the cluster interface */ @@ -584,9 +584,11 @@ DEBUGLOG("starting LVM thread\n"); /* Don't let anyone else to do work until we are started */ - pthread_mutex_lock(&lvm_start_mutex); pthread_create(&lvm_thread, &stack_attr, lvm_thread_fn, &lvm_params); + /* Don't start until the LVM thread is ready */ + pthread_barrier_wait(&lvm_start_barrier); + /* Tell the rest of the cluster our version number */ if (clops->cluster_init_completed) clops->cluster_init_completed(); @@ -1633,11 +1635,6 @@ DEBUGLOG("in sub thread: client = %p\n", client); pthread_mutex_lock(&client->bits.localsock.mutex); - /* Don't start until the LVM thread is ready */ - pthread_mutex_lock(&lvm_start_mutex); - pthread_mutex_unlock(&lvm_start_mutex); - DEBUGLOG("Sub thread ready for work.\n"); - /* Ignore SIGUSR1 (handled by master process) but enable SIGUSR2 (kills subthreads) */ sigemptyset(&ss); @@ -2004,7 +2001,8 @@ init_clvm(lvm_params->excl_uuid); /* Allow others to get moving */ - pthread_mutex_unlock(&lvm_start_mutex); + pthread_barrier_wait(&lvm_start_barrier); + DEBUGLOG("Sub thread ready for work.\n"); /* Now wait for some actual work */ while (!quit) {