Hi Lai, I combined your patches 3 and 4, and enhanced them, including the comments I sent for patch #2:
commit d7ff6cee89d7f8b4183b783d3d0a337b27d10bd2 Author: Mathieu Desnoyers <[email protected]> Date: Thu Sep 29 13:28:04 2011 -0400 urcu_defer: Use cancellation flag instead of pthread_cancel() - Provides better control over cancellation point location. - Set the futex to 0 before exiting the defer thread. This patch combines and enhances patches from Lai Jiangshan: urcu,defer_rcu: fix missing respond to a cancellation request urcu,defer_rcu: Avoid thread exit unexpected Reported-by: Lai Jiangshan <[email protected]> Signed-off-by: Mathieu Desnoyers <[email protected]> diff --git a/urcu-defer-impl.h b/urcu-defer-impl.h index d1ab046..4211f7c 100644 --- a/urcu-defer-impl.h +++ b/urcu-defer-impl.h @@ -122,6 +122,7 @@ static pthread_mutex_t rcu_defer_mutex = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t defer_thread_mutex = PTHREAD_MUTEX_INITIALIZER; static int32_t defer_thread_futex; +static int32_t defer_thread_stop; /* * Written to only by each individual deferer. Read by both the deferer and @@ -148,7 +149,6 @@ static void mutex_lock_defer(pthread_mutex_t *mutex) perror("Error in pthread mutex lock"); exit(-1); } - pthread_testcancel(); poll(NULL,0,10); } #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ @@ -186,7 +186,13 @@ static unsigned long rcu_defer_num_callbacks(void) static void wait_defer(void) { uatomic_dec(&defer_thread_futex); - cmm_smp_mb(); /* Write futex before read queue */ + /* Write futex before read queue */ + /* Write futex before read defer_thread_stop */ + cmm_smp_mb(); + if (_CMM_LOAD_SHARED(defer_thread_stop)) { + uatomic_set(&defer_thread_futex, 0); + pthread_exit(0); + } if (rcu_defer_num_callbacks()) { cmm_smp_mb(); /* Read queue before write futex */ /* Callbacks are queued, don't wait. */ @@ -359,7 +365,6 @@ void _defer_rcu(void (*fct)(void *p), void *p) void *thr_defer(void *args) { for (;;) { - pthread_testcancel(); /* * "Be green". Don't wake up the CPU if there is no RCU work * to perform whatsoever. Aims at saving laptop battery life by @@ -396,10 +401,17 @@ static void stop_defer_thread(void) int ret; void *tret; - pthread_cancel(tid_defer); + _CMM_STORE_SHARED(defer_thread_stop, 1); + /* Store defer_thread_stop before testing futex */ + cmm_smp_mb(); wake_up_defer(); + ret = pthread_join(tid_defer, &tret); assert(!ret); + + CMM_STORE_SHARED(defer_thread_stop, 0); + /* defer thread should always exit when futex value is 0 */ + assert(uatomic_read(&defer_thread_futex) == 0); } int rcu_defer_register_thread(void) -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ ltt-dev mailing list [email protected] http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev
