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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-08-03 16:41:23 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-09-23 07:42:23 -0700
commit2aef619c7524d73d18ff7b102a1706066b69141d (patch)
treeda1409acbdc4baca4858af9fbc7e413fd5efa0d0 /Documentation/RCU/checklist.txt
parent13dbf9140c726c307a9c7e2b7ff83cf95da3bb44 (diff)
downloadlinux-linaro-stable-2aef619c7524d73d18ff7b102a1706066b69141d.tar.gz
rcu: Document SRCU dead-CPU capabilities, emphasize read-side limits
The current documentation did not help someone grepping for SRCU to learn that disabling preemption is not a replacement for srcu_read_lock(), so upgrade the documentation to bring this out, not just for SRCU, but also for RCU-bh. Also document the fact that SRCU readers are respected on CPUs executing in user mode, idle CPUs, and even on offline CPUs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Diffstat (limited to 'Documentation/RCU/checklist.txt')
-rw-r--r--Documentation/RCU/checklist.txt6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index fc103d7a0474..cdb20d41a44a 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -310,6 +310,12 @@ over a rather long period of time, but improvements are always welcome!
code under the influence of preempt_disable(), you instead
need to use synchronize_irq() or synchronize_sched().
+ This same limitation also applies to synchronize_rcu_bh()
+ and synchronize_srcu(), as well as to the asynchronous and
+ expedited forms of the three primitives, namely call_rcu(),
+ call_rcu_bh(), call_srcu(), synchronize_rcu_expedited(),
+ synchronize_rcu_bh_expedited(), and synchronize_srcu_expedited().
+
12. Any lock acquired by an RCU callback must be acquired elsewhere
with softirq disabled, e.g., via spin_lock_irqsave(),
spin_lock_bh(), etc. Failing to disable irq on a given