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rcu: Remove ACCESS_ONCE() from jiffies 

Because jiffies is one of a very few variables marked "volatile", there
is no need to use ACCESS_ONCE() when accessing it.  This commit therefore
removes the redundant ACCESS_ONCE() wrappers.

Reported by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
This commit is contained in:
Paul E. McKenney 2013-12-04 18:42:03 -08:00
parent 87de1cfdc5
commit cb1e78cfa2
2 changed files with 5 additions and 5 deletions
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4
kernel/rcu/torture.c
View File

@ -1352,7 +1352,7 @@ rcu_torture_shutdown(void *arg)
unsigned long jiffies_snap;
VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
jiffies_snap = ACCESS_ONCE(jiffies);
jiffies_snap = jiffies;
while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
!kthread_should_stop()) {
delta = shutdown_time - jiffies_snap;
@ -1361,7 +1361,7 @@ rcu_torture_shutdown(void *arg)
"rcu_torture_shutdown task: %lu jiffies remaining\n",
torture_type, delta);
schedule_timeout_interruptible(delta);
jiffies_snap = ACCESS_ONCE(jiffies);
jiffies_snap = jiffies;
}
if (kthread_should_stop()) {
VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");

6
kernel/rcu/tree.c
View File

@ -837,7 +837,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
* to the next. Only do this for the primary flavor of RCU.
*/
if (rdp->rsp == rcu_state &&
ULONG_CMP_GE(ACCESS_ONCE(jiffies), rdp->rsp->jiffies_resched)) {
ULONG_CMP_GE(jiffies, rdp->rsp->jiffies_resched)) {
rdp->rsp->jiffies_resched += 5;
resched_cpu(rdp->cpu);
}
@ -847,7 +847,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp,
static void record_gp_stall_check_time(struct rcu_state *rsp)
{
unsigned long j = ACCESS_ONCE(jiffies);
unsigned long j = jiffies;
unsigned long j1;
rsp->gp_start = j;
@ -1005,7 +1005,7 @@ static void check_cpu_stall(struct rcu_state *rsp, struct rcu_data *rdp)
if (rcu_cpu_stall_suppress || !rcu_gp_in_progress(rsp))
return;
j = ACCESS_ONCE(jiffies);
j = jiffies;
/*
* Lots of memory barriers to reject false positives.