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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 <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2012-08-10 16:55:59 -07:00
parent 5fd4dc068c
commit c8020a67e6
1 changed files with 8 additions and 7 deletions
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15
kernel/rcutree.c
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@ -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++;
}
}
/*