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| author | Dongdong Deng <dongdong.deng@windriver.com> | 2010-09-28 16:32:43 +0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-10-07 10:41:06 -0700 |
| commit | 4ee0a603926cad973e4d384f48c5e279a0fd4118 (patch) | |
| tree | da507192551987d4841fccc541a5b94adfef4f01 /kernel/rcutree.c | |
| parent | b0a0f667a349247bd7f05f806b662a25653822bc (diff) | |
| download | lwn-4ee0a603926cad973e4d384f48c5e279a0fd4118.tar.gz lwn-4ee0a603926cad973e4d384f48c5e279a0fd4118.zip | |
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.c | 4 |
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) if (rcu_cpu_stall_suppress) return; - delta = jiffies - rsp->jiffies_stall; + delta = jiffies - ACCESS_ONCE(rsp->jiffies_stall); rnp = rdp->mynode; - if ((rnp->qsmask & rdp->grpmask) && delta >= 0) { + if ((ACCESS_ONCE(rnp->qsmask) & rdp->grpmask) && delta >= 0) { /* We haven't checked in, so go dump stack. */ print_cpu_stall(rsp); |