From c9e71002aacc9821e99531dcc130db88bbc8ad05 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 28 Feb 2008 11:51:07 -0800 Subject: [PATCH] rcupreempt: remove never-migrates assumption from rcu_process_callbacks() This patch fixes a potentially invalid access to a per-CPU variable in rcu_process_callbacks(). This per-CPU access needs to be done in such a way as to guarantee that the code using it cannot move to some other CPU before all uses of the value accessed have completed. Even though this code is currently only invoked from softirq context, which currrently cannot migrate to some other CPU, life would be better if this code did not silently make such an assumption. Signed-off-by: Paul E. McKenney Signed-off-by: Ingo Molnar --- kernel/rcupreempt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c index 845abcd472b..e9517014b57 100644 --- a/kernel/rcupreempt.c +++ b/kernel/rcupreempt.c @@ -952,9 +952,11 @@ static void rcu_process_callbacks(struct softirq_action *unused) { unsigned long flags; struct rcu_head *next, *list; - struct rcu_data *rdp = RCU_DATA_ME(); + struct rcu_data *rdp; - spin_lock_irqsave(&rdp->lock, flags); + local_irq_save(flags); + rdp = RCU_DATA_ME(); + spin_lock(&rdp->lock); list = rdp->donelist; if (list == NULL) { spin_unlock_irqrestore(&rdp->lock, flags); -- 2.20.1