linux-kernel - [PATCH 21/29] locking, tsx: Protect assert_spin_locked() with

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Date:	Fri, 22 Mar 2013 18:25:15 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	linux-kernel@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	x86@...nel.org, Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 21/29] locking, tsx: Protect assert_spin_locked() with _xtest()

From: Andi Kleen <ak@...ux.intel.com>

lock_is_locked aborts with lock elision. Some code does a lot of lock asserts,
which causes a lot of aborts. Add a _xtest() here so that the checking is only
done when the lock is not elided. This always happens occasionally due to
fallbacks, so there is still enough assert coverage.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 include/linux/spinlock_api_smp.h |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
index cf9bf3b..cd9269b 100644
--- a/include/linux/spinlock_api_smp.h
+++ b/include/linux/spinlock_api_smp.h
@@ -5,6 +5,8 @@
 # error "please don't include this file directly"
 #endif
 
+#include <linux/rtm.h>
+
 /*
  * include/linux/spinlock_api_smp.h
  *
@@ -17,7 +19,10 @@
 
 int in_lock_functions(unsigned long addr);
 
-#define assert_raw_spin_locked(x)	BUG_ON(!raw_spin_is_locked(x))
+#define assert_raw_spin_locked(x) do {			\
+	if (!_xtest())					\
+		BUG_ON(!raw_spin_is_locked(x));		\
+	} while (0)
 
 void __lockfunc _raw_spin_lock(raw_spinlock_t *lock)		__acquires(lock);
 void __lockfunc _raw_spin_lock_nested(raw_spinlock_t *lock, int subclass)
-- 
1.7.7.6

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