From 3842a0832a1d6eb0b31421f8810a813135967512 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Mon, 28 Nov 2011 10:42:42 -0800 Subject: rcu: Document same-context read-side constraints The intent is that a given RCU read-side critical section be confined to a single context. For example, it is illegal to invoke rcu_read_lock() in an exception handler and then invoke rcu_read_unlock() from the context of the task that received the exception. Suggested-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- include/linux/srcu.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/srcu.h') diff --git a/include/linux/srcu.h b/include/linux/srcu.h index 1eb520cd1680..e1b005918bbb 100644 --- a/include/linux/srcu.h +++ b/include/linux/srcu.h @@ -158,6 +158,11 @@ static inline int srcu_read_lock_held(struct srcu_struct *sp) * one way to indirectly wait on an SRCU grace period is to acquire * a mutex that is held elsewhere while calling synchronize_srcu() or * synchronize_srcu_expedited(). + * + * Note that srcu_read_lock() and the matching srcu_read_unlock() must + * occur in the same context, for example, it is illegal to invoke + * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() + * was invoked in process context. */ static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp) { -- cgit v1.2.3-59-g8ed1b