From b41772abebc27c61dd578b76da99aa5240b4c99a Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 21 Jun 2012 20:50:42 -0700 Subject: rcu: Stop rcu_do_batch() from multiplexing the "count" variable Commit b1420f1c (Make rcu_barrier() less disruptive) rearranged the code in rcu_do_batch(), moving the ->qlen manipulation to follow the requeueing of the callbacks. Unfortunately, this rearrangement clobbered the value of the "count" local variable before the value of rdp->qlen was adjusted, resulting in the value of rdp->qlen being inaccurate. This commit therefore introduces an index variable "i", avoiding the inadvertent multiplexing. Signed-off-by: Paul E. McKenney Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett --- kernel/rcutree.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 3b0f1337f75..38ecdda3f55 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1530,7 +1530,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) { unsigned long flags; struct rcu_head *next, *list, **tail; - int bl, count, count_lazy; + int bl, count, count_lazy, i; /* If no callbacks are ready, just return.*/ if (!cpu_has_callbacks_ready_to_invoke(rdp)) { @@ -1553,9 +1553,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) rdp->nxtlist = *rdp->nxttail[RCU_DONE_TAIL]; *rdp->nxttail[RCU_DONE_TAIL] = NULL; tail = rdp->nxttail[RCU_DONE_TAIL]; - for (count = RCU_NEXT_SIZE - 1; count >= 0; count--) - if (rdp->nxttail[count] == rdp->nxttail[RCU_DONE_TAIL]) - rdp->nxttail[count] = &rdp->nxtlist; + for (i = RCU_NEXT_SIZE - 1; i >= 0; i--) + if (rdp->nxttail[i] == rdp->nxttail[RCU_DONE_TAIL]) + rdp->nxttail[i] = &rdp->nxtlist; local_irq_restore(flags); /* Invoke callbacks. */ @@ -1583,9 +1583,9 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) if (list != NULL) { *tail = rdp->nxtlist; rdp->nxtlist = list; - for (count = 0; count < RCU_NEXT_SIZE; count++) - if (&rdp->nxtlist == rdp->nxttail[count]) - rdp->nxttail[count] = tail; + for (i = 0; i < RCU_NEXT_SIZE; i++) + if (&rdp->nxtlist == rdp->nxttail[i]) + rdp->nxttail[i] = tail; else break; } -- cgit v1.2.3