[PATCH 4.7 104/143] dm round robin: do not use this_cpu_ptr() without having preemption disabled
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-09-05 17:13:43
Also in:
lkml
4.7-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mike Snitzer <redacted>
commit 802934b2cfde463b72cc1b9bc1c081895a90be53 upstream.
Use local_irq_save() to disable preemption before calling
this_cpu_ptr().
Reported-by: Benjamin Block <redacted>
Fixes: b0b477c7e0dd ("dm round robin: use percpu 'repeat_count' and 'current_path'")
Suggested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Mike Snitzer <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-round-robin.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-round-robin.c
+++ b/drivers/md/dm-round-robin.c@@ -210,14 +210,17 @@ static struct dm_path *rr_select_path(st 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);