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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2008-01-25 23:08:24 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-01-25 23:08:24 +0300 |
| commit | e0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f (patch) | |
| tree | 92106dbd88530d3884bc6c4d1c088cba1ad8630e /kernel/rcupdate.c | |
| parent | 01c1c660f4b8086cad7a62345fd04290f3d82c8f (diff) | |
| download | linux-e0ecfa7917cafe72f4a75f87e8bb5d8d51dc534f.tar.xz | |
Preempt-RCU: fix rcu_barrier for preemptive environment.
Fix rcu_barrier() to work properly in preemptive kernel environment.
Also, the ordering of callback must be preserved while moving
callbacks to another CPU during CPU hotplug.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 0ccd0095ebdc..760dfc233a00 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -115,7 +115,17 @@ void rcu_barrier(void) 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. + */ + rcu_read_lock(); on_each_cpu(rcu_barrier_func, NULL, 0, 1); + rcu_read_unlock(); wait_for_completion(&rcu_barrier_completion); mutex_unlock(&rcu_barrier_mutex); } |