Commit 4afb6515 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'locking-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull lockdep fix from Thomas Gleixner:
 "A RT fix for lockdep.

  lockdep invokes prandom_u32() to create cookies. This worked until
  prandom_u32() was switched to the real random generator, which takes a
  spinlock for extraction, which does not work on RT when invoked from
  atomic contexts.

  lockdep has no requirement for real random numbers and it turns out
  sched_clock() is good enough to create the cookie. That works
  everywhere and is faster"

* tag 'locking-urgent-2022-06-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/lockdep: Use sched_clock() for random numbers
parents 36da9f5f 4051a817

kernel/locking/lockdep.c

+1 −1
Original line number Diff line number Diff line
@@ -5432,7 +5432,7 @@ static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock) 
			 * be guessable and still allows some pin nesting in

			 * our u32 pin_count.

			 */

			cookie.val = 1 + (prandom_u32() >> 16);

			cookie.val = 1 + (sched_clock() & 0xffff);

			hlock->pin_count += cookie.val;

			return cookie;

		}