rcu: Fix detection of abruptly-ending stall

The code that attempts to identify stalls that end just as we detect
them is broken by both flavors of initialization failure.  This commit
therefore properly initializes and computes the count of the number
of reasons why the RCU grace period is stalled.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 4b97bba7396e6194db4bf5b644ef8b5a1997c974..dc8c5284fe06a889e156f9b2d7599aeacd40cb58 100644 (file)
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -733,7 +733,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
        int cpu;
        long delta;
        unsigned long flags;
-       int ndetected;
+       int ndetected = 0;
        struct rcu_node *rnp = rcu_get_root(rsp);
 
        /* Only let one CPU complain about others per time interval. */
@@ -774,7 +774,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
         */
        rnp = rcu_get_root(rsp);
        raw_spin_lock_irqsave(&rnp->lock, flags);
-       ndetected = rcu_print_task_stall(rnp);
+       ndetected += rcu_print_task_stall(rnp);
        raw_spin_unlock_irqrestore(&rnp->lock, flags);
 
        print_cpu_stall_info_end();