Commit a8a217c22116 ("locking/core: Remove {read,spin,write}_can_lock()")
removed the definition of raw_spin_can_lock, causing the GENERIC_LOCKBREAK
spin_lock routines to poll the break_lock field when waiting on a lock.This has been reported to cause a deadlock during boot on s390, because the break_lock field is also set by the waiters, and can potentially remain set indefinitely if no other CPUs come in to take the lock after it has been released. This patch removes the explicit spinning on break_lock from the waiters, instead relying on the outer trylock operation to determine when the lock is available. Cc: Martin Schwidefsky <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Ingo Molnar <[email protected]> Fixes: a8a217c22116 ("locking/core: Remove {read,spin,write}_can_lock()") Reported-by: Sebastian Ott <[email protected]> Tested-by: Sebastian Ott <[email protected]> Signed-off-by: Will Deacon <[email protected]> --- kernel/locking/spinlock.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/locking/spinlock.c b/kernel/locking/spinlock.c index 1fd1a7543cdd..0ebb253e2199 100644 --- a/kernel/locking/spinlock.c +++ b/kernel/locking/spinlock.c @@ -68,8 +68,8 @@ void __lockfunc __raw_##op##_lock(locktype##_t *lock) \ \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - while ((lock)->break_lock) \ - arch_##op##_relax(&lock->raw_lock); \ + \ + arch_##op##_relax(&lock->raw_lock); \ } \ (lock)->break_lock = 0; \ } \ @@ -88,8 +88,8 @@ unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \ \ if (!(lock)->break_lock) \ (lock)->break_lock = 1; \ - while ((lock)->break_lock) \ - arch_##op##_relax(&lock->raw_lock); \ + \ + arch_##op##_relax(&lock->raw_lock); \ } \ (lock)->break_lock = 0; \ return flags; \ -- 2.1.4
