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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-11-28 10:42:42 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2011-12-11 10:32:06 -0800
commit3842a0832a1d6eb0b31421f8810a813135967512 (patch)
tree67aff02fde9c32e647d7b3c4cea948d7867f664d /include/linux/srcu.h
parentf0e7c19db8798b4b991a2c71911e71f5dfdb348f (diff)
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 <peterz@infradead.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/srcu.h')
-rw-r--r--include/linux/srcu.h5
1 files changed, 5 insertions, 0 deletions
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)
{