path: root/kernel
diff options
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2008-02-28 11:51:07 -0800
committerIngo Molnar <mingo@elte.hu>2008-02-29 20:21:13 +0100
commitc9e71002aacc9821e99531dcc130db88bbc8ad05 (patch)
tree2446b59e33eccc53ff8a04179588296bc43c0f0f /kernel
parentae778869ae4549628b9e83efe958c3aaa63ed1b9 (diff)
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 <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/rcupreempt.c b/kernel/rcupreempt.c
index 845abcd472b0..e9517014b57c 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);

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