Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull random fixes from Ted Ts'o:
 "Fix a circular locking dependency in random's collection of cputime
  used by a thread when it exits."

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: fix locking dependency with the tasklist_lock

1 files changed, 8 insertions, 4 deletions

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 594bda9dcfc8..32a6c5764950 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -852,6 +852,7 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
                       int reserved)
 {
         unsigned long flags;
+        int wakeup_write = 0;
 
         /* Hold lock while accounting */
         spin_lock_irqsave(&r->lock, flags);
@@ -873,10 +874,8 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
                 else
                         r->entropy_count = reserved;
 
-                if (r->entropy_count < random_write_wakeup_thresh) {
-                        wake_up_interruptible(&random_write_wait);
-                        kill_fasync(&fasync, SIGIO, POLL_OUT);
-                }
+                if (r->entropy_count < random_write_wakeup_thresh)
+                        wakeup_write = 1;
         }
 
         DEBUG_ENT("debiting %zu entropy credits from %s%s\n",
@@ -884,6 +883,11 @@ static size_t account(struct entropy_store *r, size_t nbytes, int min,
 
         spin_unlock_irqrestore(&r->lock, flags);
 
+        if (wakeup_write) {
+                wake_up_interruptible(&random_write_wait);
+                kill_fasync(&fasync, SIGIO, POLL_OUT);
+        }
+
         return nbytes;
 }