Re: [PATCH] bcache: Fix a sleep-in-atomic bug

[Jia-Ju Bai]

On 05/31/2017 03:23 PM, Jia-Ju Bai wrote:

The driver may sleep under a spin lock, and the function call path is:
journal_wait_for_write (acquire the lock by spin_lock)
   closure_sync
     schedule -->  may sleep

To fix it, the lock is released before "closure_sync", and the lock is
acquired again after this function.

Signed-off-by: Jia-Ju Bai<baijiaju1...@163.com>
---
  drivers/md/bcache/journal.c |    1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index 1198e53..ad47c36 100644
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -724,6 +724,7 @@ static struct journal_write *journal_wait_for_write(struct 
cache_set *c,
                        btree_flush_write(c);
                }

+               spin_unlock(&c->journal.lock);
                closure_sync(&cl);
                spin_lock(&c->journal.lock);
                wait = true;

Sorry, my patch is not correct, and it will cause double unlock.
Please ignore my patch.


Jia-Ju Bai