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rcu: Fix synchronize_rcu_expedited() header comment 

This commit brings the synchronize_rcu_expedited() function's header
comment into line with the new implementation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2016-01-28 18:48:37 -08:00
parent a1e1224849
commit 26ece8ef6e
1 changed files with 13 additions and 7 deletions
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20
kernel/rcu/tree_plugin.h
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@ -722,13 +722,19 @@ static void sync_rcu_exp_handler(void *info)
* synchronize_rcu_expedited - Brute-force RCU grace period
*
* Wait for an RCU-preempt grace period, but expedite it. The basic
* idea is to invoke synchronize_sched_expedited() to push all the tasks to
* the ->blkd_tasks lists and wait for this list to drain. This consumes
* significant time on all CPUs and is unfriendly to real-time workloads,
* so is thus not recommended for any sort of common-case code.
* In fact, if you are using synchronize_rcu_expedited() in a loop,
* please restructure your code to batch your updates, and then Use a
* single synchronize_rcu() instead.
* idea is to IPI all non-idle non-nohz online CPUs. The IPI handler
* checks whether the CPU is in an RCU-preempt critical section, and
* if so, it sets a flag that causes the outermost rcu_read_unlock()
* to report the quiescent state. On the other hand, if the CPU is
* not in an RCU read-side critical section, the IPI handler reports
* the quiescent state immediately.
*
* Although this is a greate improvement over previous expedited
* implementations, it is still unfriendly to real-time workloads, so is
* thus not recommended for any sort of common-case code. In fact, if
* you are using synchronize_rcu_expedited() in a loop, please restructure
* your code to batch your updates, and then Use a single synchronize_rcu()
* instead.
*/
void synchronize_rcu_expedited(void)
{