Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-17 09:31:50 +00:00
Code Issues Packages Projects Releases Wiki Activity

Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

Browse Source 
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcupdate: fix bug of rcu_barrier*()
  profiling: fix !procfs build

Fixed trivial conflicts in 'include/linux/profile.h'
This commit is contained in:
Linus Torvalds 2008-10-23 09:38:55 -07:00
commit f2e4bd2b37
1 changed files with 10 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
kernel/rcupdate.c
View File

@ -119,18 +119,19 @@ static void _rcu_barrier(enum rcu_barrier type)
/* Take cpucontrol mutex to protect against CPU hotplug */
mutex_lock(&rcu_barrier_mutex);
init_completion(&rcu_barrier_completion);
atomic_set(&rcu_barrier_cpu_count, 0);
/*
* The queueing of callbacks in all CPUs must be atomic with
* respect to RCU, otherwise one CPU may queue a callback,
* wait for a grace period, decrement barrier count and call
* complete(), while other CPUs have not yet queued anything.
* So, we need to make sure that grace periods cannot complete
* until all the callbacks are queued.
* Initialize rcu_barrier_cpu_count to 1, then invoke
* rcu_barrier_func() on each CPU, so that each CPU also has
* incremented rcu_barrier_cpu_count. Only then is it safe to
* decrement rcu_barrier_cpu_count -- otherwise the first CPU
* might complete its grace period before all of the other CPUs
* did their increment, causing this function to return too
* early.
*/
rcu_read_lock();
atomic_set(&rcu_barrier_cpu_count, 1);
on_each_cpu(rcu_barrier_func, (void *)type, 1);
rcu_read_unlock();
if (atomic_dec_and_test(&rcu_barrier_cpu_count))
complete(&rcu_barrier_completion);
wait_for_completion(&rcu_barrier_completion);
mutex_unlock(&rcu_barrier_mutex);
}