From c8020a67e625c714c4dbedc8ae2944b461e204ec Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 10 Aug 2012 16:55:59 -0700 Subject: [PATCH] rcu: Protect rcu_node accesses during CPU stall warnings The print_other_cpu_stall() function accesses a number of rcu_node fields without protection from the ->lock. In theory, this is not a problem because the fields accessed are all integers, but in practice the compiler can get nasty. Therefore, the commit extends the existing critical section to cover the entire loop body. Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 2c4ee4cdbc0e..2cf8eb3e2d43 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -746,14 +746,15 @@ static void print_other_cpu_stall(struct rcu_state *rsp) rcu_for_each_leaf_node(rsp, rnp) { raw_spin_lock_irqsave(&rnp->lock, flags); ndetected += rcu_print_task_stall(rnp); + if (rnp->qsmask != 0) { + for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) + if (rnp->qsmask & (1UL << cpu)) { + print_cpu_stall_info(rsp, + rnp->grplo + cpu); + ndetected++; + } + } raw_spin_unlock_irqrestore(&rnp->lock, flags); - if (rnp->qsmask == 0) - continue; - for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++) - if (rnp->qsmask & (1UL << cpu)) { - print_cpu_stall_info(rsp, rnp->grplo + cpu); - ndetected++; - } } /*