[PATCH 07/16] rcu: Save and restore irq flags in rcu_gp_cleanup()

Pranith Kumar
2014-07-23T05:10:55Z

We use raw_spin_lock_irqsave/restore() family of functions throughout the code
but for two locations. This commit replaces raw_spin_lock_irq()/unlock_irq()
with irqsave/restore() in one such location. This is not strictly necessary,
so I did not change the other location. I will update the other location if
this is accepted :)

This commit changes raw_spin_lock_irq()/unlock_irq() to lock_irqsave()/restore().

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
---
kernel/rcu/tree.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b14cecd..5dcbf36 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1706,13 +1706,13 @@ static int rcu_gp_fqs(struct rcu_state *rsp, int fqs_state_in)
*/
static void rcu_gp_cleanup(struct rcu_state *rsp)
{
- unsigned long gp_duration;
+ unsigned long gp_duration, flags;
bool needgp = false;
int nocb = 0;
struct rcu_data *rdp;
struct rcu_node *rnp = rcu_get_root(rsp);

- raw_spin_lock_irq(&rnp->lock);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
gp_duration = jiffies - rsp->gp_start;
if (gp_duration > rsp->gp_max)
@@ -1726,7 +1726,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
* safe for us to drop the lock in order to mark the grace
* period as completed in all of the rcu_node structures.
*/
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);

/*
* Propagate new ->completed value to rcu_node structures so
@@ -1738,7 +1738,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
* grace period is recorded in any of the rcu_node structures.
*/
rcu_for_each_node_breadth_first(rsp, rnp) {
- raw_spin_lock_irq(&rnp->lock);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock();
ACCESS_ONCE(rnp->completed) = rsp->gpnum;
rdp = this_cpu_ptr(rsp->rda);
@@ -1746,11 +1746,11 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
needgp = __note_gp_changes(rsp, rnp, rdp) || needgp;
/* smp_mb() provided by prior unlock-lock pair. */
nocb += rcu_future_gp_cleanup(rsp, rnp);
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
cond_resched();
}
rnp = rcu_get_root(rsp);
- raw_spin_lock_irq(&rnp->lock);
+ raw_spin_lock_irqsave(&rnp->lock, flags);
smp_mb__after_unlock_lock(); /* Order GP before ->completed update. */
rcu_nocb_gp_set(rnp, nocb);

@@ -1767,7 +1767,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
ACCESS_ONCE(rsp->gpnum),
TPS("newreq"));
}
- raw_spin_unlock_irq(&rnp->lock);
+ raw_spin_unlock_irqrestore(&rnp->lock, flags);
}

/*
--
2.0.0.rc2