From 81ad2e193e8072f8246212d7eaba72769306c2e4 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 3 Jun 2011 12:42:00 -0400 Subject: [PATCH] Provide pthread_atfork-friendly interfaces Provides call_rcu_before_fork() and call_rcu_after_fork_parent() to go with the existing call_rcu_after_fork_child(). Signed-off-by: Paul E. McKenney Signed-off-by: Mathieu Desnoyers --- README | 4 ++++ urcu-call-rcu.c | 26 +++++++++++++++++++++++++- 2 files changed, 29 insertions(+), 1 deletion(-) diff --git a/README b/README index f7f0dec..56e98d7 100644 --- a/README +++ b/README @@ -204,3 +204,7 @@ Interaction with fork() liburcu-bp, which is designed to handle fork() by calling rcu_bp_before_fork, rcu_bp_after_fork_parent and rcu_bp_after_fork_child. + + Applications that use call_rcu() are required to invoke + call_rcu_after_fork_child() from the child process after a + successful fork() system call that is not followed by exec(). diff --git a/urcu-call-rcu.c b/urcu-call-rcu.c index bb56dbb..9cc56c5 100644 --- a/urcu-call-rcu.c +++ b/urcu-call-rcu.c @@ -565,14 +565,38 @@ void free_all_cpu_call_rcu_data(void) } } +/* + * Acquire the call_rcu_mutex in order to ensure that the child sees + * all of the call_rcu() data structures in a consistent state. + * Suitable for pthread_atfork() and friends. + */ +void call_rcu_before_fork(void) +{ + call_rcu_lock(&call_rcu_mutex); +} + +/* + * Clean up call_rcu data structures in the parent of a successful fork() + * that is not followed by exec() in the child. Suitable for + * pthread_atfork() and friends. + */ +void call_rcu_after_fork_parent(void) +{ + call_rcu_unlock(&call_rcu_mutex); +} + /* * Clean up call_rcu data structures in the child of a successful fork() - * that is not followed by exec(). + * that is not followed by exec(). Suitable for pthread_atfork() and + * friends. */ void call_rcu_after_fork_child(void) { struct call_rcu_data *crdp; + /* Release the mutex. */ + call_rcu_unlock(&call_rcu_mutex); + /* * Allocate a new default call_rcu_data structure in order * to get a working call_rcu thread to go with it. -- 2.34.1