diff options
| -rw-r--r-- | lib/frr_pthread.c | 35 | ||||
| -rw-r--r-- | lib/frr_pthread.h | 11 |
2 files changed, 46 insertions, 0 deletions
diff --git a/lib/frr_pthread.c b/lib/frr_pthread.c index 1ffa5934aa..3a4bc712fc 100644 --- a/lib/frr_pthread.c +++ b/lib/frr_pthread.c @@ -92,9 +92,14 @@ struct frr_pthread *frr_pthread_new(const struct frr_pthread_attr *attr, MTYPE_PTHREAD_PRIM, sizeof(pthread_mutex_t)); fpt->running_cond = XCALLOC(MTYPE_PTHREAD_PRIM, sizeof(pthread_cond_t)); + pthread_mutex_init(fpt->running_cond_mtx, NULL); pthread_cond_init(fpt->running_cond, NULL); + pthread_mutex_init(&fpt->startup_cond_mtx, NULL); + pthread_cond_init(&fpt->startup_cond, NULL); + fpt->started = false; + frr_with_mutex (&frr_pthread_list_mtx) { listnode_add(frr_pthread_list, fpt); } @@ -108,6 +113,8 @@ static void frr_pthread_destroy_nolock(struct frr_pthread *fpt) pthread_mutex_destroy(&fpt->mtx); pthread_mutex_destroy(fpt->running_cond_mtx); pthread_cond_destroy(fpt->running_cond); + pthread_mutex_destroy(&fpt->startup_cond_mtx); + pthread_cond_destroy(&fpt->startup_cond); XFREE(MTYPE_FRR_PTHREAD, fpt->name); XFREE(MTYPE_PTHREAD_PRIM, fpt->running_cond_mtx); XFREE(MTYPE_PTHREAD_PRIM, fpt->running_cond); @@ -140,11 +147,34 @@ int frr_pthread_set_name(struct frr_pthread *fpt) return ret; } +/* New pthread waits before running */ +static void frr_pthread_wait_startup(struct frr_pthread *fpt) +{ + frr_with_mutex (&fpt->startup_cond_mtx) { + while (!fpt->started) + pthread_cond_wait(&fpt->startup_cond, + &fpt->startup_cond_mtx); + } +} + +/* Parent pthread allows new pthread to start running */ +static void frr_pthread_notify_startup(struct frr_pthread *fpt) +{ + frr_with_mutex (&fpt->startup_cond_mtx) { + fpt->started = true; + pthread_cond_signal(&fpt->startup_cond); + } +} + static void *frr_pthread_inner(void *arg) { struct frr_pthread *fpt = arg; + /* The new pthead waits until the parent allows it to continue. */ + frr_pthread_wait_startup(fpt); + rcu_thread_start(fpt->rcu_thread); + return fpt->attr.start(fpt); } @@ -169,6 +199,9 @@ int frr_pthread_run(struct frr_pthread *fpt, const pthread_attr_t *attr) /* Restore caller's signals */ pthread_sigmask(SIG_SETMASK, &oldsigs, NULL); + /* Allow new child pthread to start */ + frr_pthread_notify_startup(fpt); + /* * Per pthread_create(3), the contents of fpt->thread are undefined if * pthread_create() did not succeed. Reset this value to zero. @@ -250,6 +283,8 @@ int frr_pthread_non_controlled_startup(pthread_t thread, const char *name, fpt->thread = thread; fpt->rcu_thread = rcu_thread; + fpt->started = true; + frr_pthread_inner(fpt); return 0; diff --git a/lib/frr_pthread.h b/lib/frr_pthread.h index 1e1b8d7fd3..bb751b7071 100644 --- a/lib/frr_pthread.h +++ b/lib/frr_pthread.h @@ -47,6 +47,17 @@ struct frr_pthread { struct frr_pthread_attr attr; /* + * Startup serialization: newly-started pthreads wait at a point + * very early in life so that there isn't a race with the + * starting pthread. The OS 'start' apis don't make any guarantees + * about which pthread runs first - the existing pthread that has + * called the 'start' api, or the new pthread that is just starting. + */ + pthread_cond_t startup_cond; + pthread_mutex_t startup_cond_mtx; + atomic_bool started; + + /* * Notification mechanism for allowing pthreads to notify their parents * when they are ready to do work. This mechanism has two associated * functions: |