diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-05-06 18:49:21 +0200 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2010-05-06 18:49:21 +0200 |
commit | cc631fb732b8ccd6a0cc45557475ea09b0c21a68 (patch) | |
tree | 37e8c84f227a21d628a9d3a96dbbf5fedd506db1 | |
parent | 94458d5ecb3da844823cc191e73e5c5ead98a464 (diff) |
sched: correctly place paranioa memory barriers in synchronize_sched_expedited()
The memory barriers must be in the SMP case, not in the !SMP case.
Also add a barrier after the atomic_inc() in order to ensure that
other CPUs see post-synchronize_sched_expedited() actions as following
the expedited grace period.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
-rw-r--r-- | kernel/sched.c | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index e9c6d798831..155a16d5214 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8932,6 +8932,15 @@ struct cgroup_subsys cpuacct_subsys = { void synchronize_sched_expedited(void) { +} +EXPORT_SYMBOL_GPL(synchronize_sched_expedited); + +#else /* #ifndef CONFIG_SMP */ + +static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); + +static int synchronize_sched_expedited_cpu_stop(void *data) +{ /* * There must be a full memory barrier on each affected CPU * between the time that try_stop_cpus() is called and the @@ -8943,16 +8952,7 @@ void synchronize_sched_expedited(void) * necessary. Do smp_mb() anyway for documentation and * robustness against future implementation changes. */ - smp_mb(); -} -EXPORT_SYMBOL_GPL(synchronize_sched_expedited); - -#else /* #ifndef CONFIG_SMP */ - -static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0); - -static int synchronize_sched_expedited_cpu_stop(void *data) -{ + smp_mb(); /* See above comment block. */ return 0; } @@ -8990,6 +8990,7 @@ void synchronize_sched_expedited(void) get_online_cpus(); } atomic_inc(&synchronize_sched_expedited_count); + smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */ put_online_cpus(); } EXPORT_SYMBOL_GPL(synchronize_sched_expedited); |