[PATCH] rcu_do_batch: make ->qlen decrement irq safe

rcu_do_batch() decrements rdp->qlen with irqs enabled. This is not good, it can also be modified by call_rcu() from interrupt. Decrement ->qlen once with irqs disabled, after a main loop. Signed-off-by: Oleg Nesterov <[email protected]> Cc: Dipankar Sarma <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
kawasaki · Sep 13, 2006 · dd9daa2 · dd9daa2
1 parent 7fbb364
commit dd9daa2
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
@@ -241,12 +241,16 @@ static void rcu_do_batch(struct rcu_data *rdp)
 		next = rdp->donelist = list->next;
 		list->func(list);
 		list = next;
-		rdp->qlen--;
 		if (++count >= rdp->blimit)
 			break;
 	}
+
+	local_irq_disable();
+	rdp->qlen -= count;
+	local_irq_enable();
 	if (rdp->blimit == INT_MAX && rdp->qlen <= qlowmark)
 		rdp->blimit = blimit;
+
 	if (!rdp->donelist)
 		rdp->donetail = &rdp->donelist;
 	else