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authorDongdong Deng <dongdong.deng@windriver.com>2010-09-28 04:32:43 -0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-10-07 13:41:06 -0400
commit4ee0a603926cad973e4d384f48c5e279a0fd4118 (patch)
treeda507192551987d4841fccc541a5b94adfef4f01 /kernel/rcutree.c
parentb0a0f667a349247bd7f05f806b662a25653822bc (diff)
rcu: using ACCESS_ONCE() to observe the jiffies_stall/rnp->qsmask value
Using ACCESS_ONCE() to observe the jiffies_stall/rnp->qsmask value due to the caller didn't hold the root_rcu/rnp node's lock. Although use without ACCESS_ONCE() is safe due to the value loaded being used but once, the ACCESS_ONCE() is a good documentation aid -- the variables are being loaded without the services of a lock. Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com> CC: Dipankar Sarma <dipankar@in.ibm.com> CC: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index e75073504a31..ccdc04c47981 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -545,9 +545,9 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
545 545
546 if (rcu_cpu_stall_suppress) 546 if (rcu_cpu_stall_suppress)
547 return; 547 return;
548 delta = jiffies - rsp->jiffies_stall; 548 delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall);
549 rnp = rdp->mynode; 549 rnp = rdp->mynode;
550 if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { 550 if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) {
551 551
552 /* We haven't checked in, so go dump stack. */ 552 /* We haven't checked in, so go dump stack. */
553 print_cpu_stall(rsp); 553 print_cpu_stall(rsp);