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dm round robin: do not use this_cpu_ptr() without having preemption disabled 

Use local_irq_save() to disable preemption before calling
this_cpu_ptr().

Reported-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Fixes: b0b477c7e0 ("dm round robin: use percpu 'repeat_count' and 'current_path'")
Cc: stable@vger.kernel.org # 4.6+
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2016-08-05 12:29:06 -04:00
parent 694d0d0bb2
commit 802934b2cf
1 changed files with 5 additions and 2 deletions
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7
drivers/md/dm-round-robin.c
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@ -210,14 +210,17 @@ static struct dm_path *rr_select_path(struct path_selector *ps, size_t nr_bytes)
struct path_info *pi = NULL;
struct dm_path *current_path = NULL;
local_irq_save(flags);
current_path = *this_cpu_ptr(s->current_path);
if (current_path) {
percpu_counter_dec(&s->repeat_count);
if (percpu_counter_read_positive(&s->repeat_count) > 0)
if (percpu_counter_read_positive(&s->repeat_count) > 0) {
local_irq_restore(flags);
return current_path;
}
}
spin_lock_irqsave(&s->lock, flags);
spin_lock(&s->lock);
if (!list_empty(&s->valid_paths)) {
pi = list_entry(s->valid_paths.next, struct path_info, list);
list_move_tail(&pi->list, &s->valid_paths);