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Fix a circular locking dependency in random's collection of cputime

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used by a thread when it exits.
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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
This commit is contained in:
Linus Torvalds 2013-03-08 14:42:16 -08:00
commit c77f8bf918
1 changed files with 8 additions and 4 deletions
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12
drivers/char/random.c
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@ -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;
}