Merge tag 'v4.4.16' into linux-linaro-lsk-v4.4lsk-v4.4-16.07

This is the 4.4.16 stable release

# gpg: Signature made Wed 27 Jul 2016 17:48:38 BST using RSA key ID 6092693E
# gpg: requesting key 6092693E from hkp server the.earth.li
# gpg: key 6092693E: public key "Greg Kroah-Hartman (Linux kernel stable release signing key) <greg@kroah.com>" imported
# gpg: public key of ultimately trusted key B4B0BED6 not found
# gpg: 2 marginal(s) needed, 1 complete(s) needed, PGP trust model
# gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
# gpg: Total number processed: 1
# gpg:               imported: 1  (RSA: 1)
# gpg: Good signature from "Greg Kroah-Hartman (Linux kernel stable release signing key) <greg@kroah.com>"
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 647F 2865 4894 E3BD 4571  99BE 38DB BDC8 6092 693E

1 files changed, 17 insertions, 36 deletions

diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
index 7d633f19e38a..1885fc44b1bc 100644
--- a/include/asm-generic/qspinlock.h
+++ b/include/asm-generic/qspinlock.h
@@ -21,37 +21,33 @@
 #include <asm-generic/qspinlock_types.h>
 
 /**
+ * queued_spin_unlock_wait - wait until the _current_ lock holder releases the lock
+ * @lock : Pointer to queued spinlock structure
+ *
+ * There is a very slight possibility of live-lock if the lockers keep coming
+ * and the waiter is just unfortunate enough to not see any unlock state.
+ */
+#ifndef queued_spin_unlock_wait
+extern void queued_spin_unlock_wait(struct qspinlock *lock);
+#endif
+
+/**
  * queued_spin_is_locked - is the spinlock locked?
  * @lock: Pointer to queued spinlock structure
  * Return: 1 if it is locked, 0 otherwise
  */
+#ifndef queued_spin_is_locked
 static __always_inline int queued_spin_is_locked(struct qspinlock *lock)
 {
 	/*
-	 * queued_spin_lock_slowpath() can ACQUIRE the lock before
-	 * issuing the unordered store that sets _Q_LOCKED_VAL.
-	 *
-	 * See both smp_cond_acquire() sites for more detail.
-	 *
-	 * This however means that in code like:
-	 *
-	 *   spin_lock(A)		spin_lock(B)
-	 *   spin_unlock_wait(B)	spin_is_locked(A)
-	 *   do_something()		do_something()
-	 *
-	 * Both CPUs can end up running do_something() because the store
-	 * setting _Q_LOCKED_VAL will pass through the loads in
-	 * spin_unlock_wait() and/or spin_is_locked().
+	 * See queued_spin_unlock_wait().
 	 *
-	 * Avoid this by issuing a full memory barrier between the spin_lock()
-	 * and the loads in spin_unlock_wait() and spin_is_locked().
-	 *
-	 * Note that regular mutual exclusion doesn't care about this
-	 * delayed store.
+	 * Any !0 state indicates it is locked, even if _Q_LOCKED_VAL
+	 * isn't immediately observable.
 	 */
-	smp_mb();
-	return atomic_read(&lock->val) & _Q_LOCKED_MASK;
+	return atomic_read(&lock->val);
 }
+#endif
 
 /**
  * queued_spin_value_unlocked - is the spinlock structure unlocked?
@@ -121,21 +117,6 @@ static __always_inline void queued_spin_unlock(struct qspinlock *lock)
 }
 #endif
 
-/**
- * queued_spin_unlock_wait - wait until current lock holder releases the lock
- * @lock : Pointer to queued spinlock structure
- *
- * There is a very slight possibility of live-lock if the lockers keep coming
- * and the waiter is just unfortunate enough to not see any unlock state.
- */
-static inline void queued_spin_unlock_wait(struct qspinlock *lock)
-{
-	/* See queued_spin_is_locked() */
-	smp_mb();
-	while (atomic_read(&lock->val) & _Q_LOCKED_MASK)
-		cpu_relax();
-}
-
 #ifndef virt_spin_lock
 static __always_inline bool virt_spin_lock(struct qspinlock *lock)
 {