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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-11-28 10:42:42 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2011-12-11 10:32:06 -0800 |
| commit | 3842a0832a1d6eb0b31421f8810a813135967512 (patch) | |
| tree | 67aff02fde9c32e647d7b3c4cea948d7867f664d /include/linux/srcu.h | |
| parent | rcu: Identify dyntick-idle CPUs on first force_quiescent_state() pass (diff) | |
| download | linux-dev-3842a0832a1d6eb0b31421f8810a813135967512.tar.xz linux-dev-3842a0832a1d6eb0b31421f8810a813135967512.zip | |
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.h | 5 |
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) { |