Patch "locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support" has been added to the 4.2-stable tree

Patch "locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support" has been added to the 4.2-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     locking-qspinlock-x86-only-emit-the-test-and-set-fallback-when-building-guest-support.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From a6b277857fd2c990bc208ca1958d3f34d26052f7 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Sat, 5 Sep 2015 16:55:05 +0200
Subject: locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support

From: Peter Zijlstra <peterz@infradead.org>

commit a6b277857fd2c990bc208ca1958d3f34d26052f7 upstream.

Only emit the test-and-set fallback for Hypervisors lacking
PARAVIRT_SPINLOCKS support when building for guests.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
index 8dde3bdc4a05..eaba08076030 100644
--- a/arch/x86/include/asm/qspinlock.h
+++ b/arch/x86/include/asm/qspinlock.h
@@ -39,8 +39,8 @@ static inline void queued_spin_unlock(struct qspinlock *lock)
 }
 #endif
 
+#ifdef CONFIG_PARAVIRT
 #define virt_spin_lock virt_spin_lock
-
 static inline bool virt_spin_lock(struct qspinlock *lock)
 {
 	if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
@@ -59,6 +59,7 @@ static inline bool virt_spin_lock(struct qspinlock *lock)
 
 	return true;
 }
+#endif /* CONFIG_PARAVIRT */
 
 #include <asm-generic/qspinlock.h>
 


Patches currently in stable-queue which might be from peterz@infradead.org are

queue-4.2/time-fix-timekeeping_freqadjust-s-incorrect-use-of-abs-instead-of-abs64.patch
queue-4.2/perf-x86-intel-fix-constraint-access.patch
queue-4.2/sched-access-local-runqueue-directly-in-single_task_running.patch
queue-4.2/locking-qspinlock-x86-only-emit-the-test-and-set-fallback-when-building-guest-support.patch
queue-4.2/locking-qspinlock-x86-fix-performance-regression-under-unaccelerated-vms.patch