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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-09-29 12:34:40 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2015-12-04 12:26:51 -0800
commit886ef5a18a4a771d5fdc0e23ae9373bb35d529e7 (patch)
treecbecef5a7f6313614c0b8617411a764ab24c91ab /kernel/rcu
parent1de6e56ddc043437d335ee0455a1b34b73510c91 (diff)
downloadlinux-sh-886ef5a18a4a771d5fdc0e23ae9373bb35d529e7.tar.gz
rcu: Move smp_mb() from rcu_seq_snap() to rcu_exp_gp_seq_snap()
The memory barrier in rcu_seq_snap() is needed only for grace periods, so this commit moves it to the grace-period-oriented wrapper rcu_exp_gp_seq_snap(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index bd2605c144cc..a4a0475aede9 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3347,7 +3347,6 @@ static unsigned long rcu_seq_snap(unsigned long *sp)
{
unsigned long s;
- smp_mb(); /* Caller's modifications seen first by other CPUs. */
s = (READ_ONCE(*sp) + 3) & ~0x1;
smp_mb(); /* Above access must not bleed into critical section. */
return s;
@@ -3374,6 +3373,7 @@ static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
}
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
{
+ smp_mb(); /* Caller's modifications seen first by other CPUs. */
return rcu_seq_snap(&rsp->expedited_sequence);
}
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)