From cb1e78cfa267453bb19e7edafd214c03834b664c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 4 Dec 2013 18:42:03 -0800 Subject: [PATCH] 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 Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcu/torture.c | 4 ++-- kernel/rcu/tree.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/kernel/rcu/torture.c b/kernel/rcu/torture.c index ab7dd192a50..022c5312b72 100644 --- a/kernel/rcu/torture.c +++ b/kernel/rcu/torture.c @@ -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"); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 321feef0f5c..73c3cd2b87a 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -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. -- 2.41.0