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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-05-07 13:43:30 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-07-02 12:34:03 -0700
commit74d874e7bdc5b09cedcc7da0de44db25888eea10 (patch)
tree72cf891de767436eaba95e06e0a575f461297f8e /Documentation/RCU/rcubarrier.txt
parentcba6d0d64ee53772b285d0c0c288deefbeaf7775 (diff)
downloadlinux-linaro-stable-74d874e7bdc5b09cedcc7da0de44db25888eea10.tar.gz
rcu: Update documentation to cover call_srcu() and srcu_barrier().
The advent of call_srcu() and srcu_barrier() obsoleted some of the documentation, so this commit brings that up to date. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'Documentation/RCU/rcubarrier.txt')
-rw-r--r--Documentation/RCU/rcubarrier.txt15
1 files changed, 4 insertions, 11 deletions
diff --git a/Documentation/RCU/rcubarrier.txt b/Documentation/RCU/rcubarrier.txt
index e439a0edee22..38428c125135 100644
--- a/Documentation/RCU/rcubarrier.txt
+++ b/Documentation/RCU/rcubarrier.txt
@@ -79,8 +79,6 @@ complete. Pseudo-code using rcu_barrier() is as follows:
2. Execute rcu_barrier().
3. Allow the module to be unloaded.
-Quick Quiz #1: Why is there no srcu_barrier()?
-
The rcutorture module makes use of rcu_barrier in its exit function
as follows:
@@ -162,7 +160,7 @@ for any pre-existing callbacks to complete.
Then lines 55-62 print status and do operation-specific cleanup, and
then return, permitting the module-unload operation to be completed.
-Quick Quiz #2: Is there any other situation where rcu_barrier() might
+Quick Quiz #1: Is there any other situation where rcu_barrier() might
be required?
Your module might have additional complications. For example, if your
@@ -242,7 +240,7 @@ reaches zero, as follows:
4 complete(&rcu_barrier_completion);
5 }
-Quick Quiz #3: What happens if CPU 0's rcu_barrier_func() executes
+Quick Quiz #2: What happens if CPU 0's rcu_barrier_func() executes
immediately (thus incrementing rcu_barrier_cpu_count to the
value one), but the other CPU's rcu_barrier_func() invocations
are delayed for a full grace period? Couldn't this result in
@@ -259,12 +257,7 @@ so that your module may be safely unloaded.
Answers to Quick Quizzes
-Quick Quiz #1: Why is there no srcu_barrier()?
-
-Answer: Since there is no call_srcu(), there can be no outstanding SRCU
- callbacks. Therefore, there is no need to wait for them.
-
-Quick Quiz #2: Is there any other situation where rcu_barrier() might
+Quick Quiz #1: Is there any other situation where rcu_barrier() might
be required?
Answer: Interestingly enough, rcu_barrier() was not originally
@@ -278,7 +271,7 @@ Answer: Interestingly enough, rcu_barrier() was not originally
implementing rcutorture, and found that rcu_barrier() solves
this problem as well.
-Quick Quiz #3: What happens if CPU 0's rcu_barrier_func() executes
+Quick Quiz #2: What happens if CPU 0's rcu_barrier_func() executes
immediately (thus incrementing rcu_barrier_cpu_count to the
value one), but the other CPU's rcu_barrier_func() invocations
are delayed for a full grace period? Couldn't this result in