locking: remove unused double_spin_lock()

double_spin_lock() has no callers, and it can't be used without additional
lockdep annotations, remove it.

Signed-off-by: Oleg Nesterov <[e-mail]>
Cc: Arjan van de Ven <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>

include/linux/spinlock.h

···
 })
 
 /*
- * Locks two spinlocks l1 and l2.
- * l1_first indicates if spinlock l1 should be taken first.
- */
-static inline void double_spin_lock(spinlock_t *l1, spinlock_t *l2,
-				    bool l1_first)
-	__acquires(l1)
-	__acquires(l2)
-{
-	if (l1_first) {
-		spin_lock(l1);
-		spin_lock(l2);
-	} else {
-		spin_lock(l2);
-		spin_lock(l1);
-	}
-}
-
-/*
- * Unlocks two spinlocks l1 and l2.
- * l1_taken_first indicates if spinlock l1 was taken first and therefore
- * should be released after spinlock l2.
- */
-static inline void double_spin_unlock(spinlock_t *l1, spinlock_t *l2,
-				      bool l1_taken_first)
-	__releases(l1)
-	__releases(l2)
-{
-	if (l1_taken_first) {
-		spin_unlock(l2);
-		spin_unlock(l1);
-	} else {
-		spin_unlock(l1);
-		spin_unlock(l2);
-	}
-}
-
-/*
  * Pull the atomic_t declaration:
  * (asm-mips/atomic.h needs above definitions)
  */