From a81f564a7bf1655bc6a6a03bac31a641aeb75754 Mon Sep 17 00:00:00 2001
From: Vikram Mulukutla <markivx@codeaurora.org>
Date: Thu, 4 Oct 2012 17:13:22 -0700
Subject: [PATCH] --- yaml --- r: 330091 b: refs/heads/master c:
 214f766ea0909e743122966c4617b3a112e405d7 h: refs/heads/master i:   330089:
 1a410405b4f0b9a9376d2ecd10d8f35f3e50fdb8   330087:
 4bf0252c80923bb34195b59b818bf339c30af828 v: v3

---
 [refs]                     |  2 +-
 trunk/lib/spinlock_debug.c | 32 ++++++++++++++++++--------------
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/[refs] b/[refs]
index 937eefbc2cfd..bc26ca3072a5 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ca279cf1065fb689abea1dc7d8c11787729bb185
+refs/heads/master: 214f766ea0909e743122966c4617b3a112e405d7
diff --git a/trunk/lib/spinlock_debug.c b/trunk/lib/spinlock_debug.c
index eb10578ae055..0374a596cffa 100644
--- a/trunk/lib/spinlock_debug.c
+++ b/trunk/lib/spinlock_debug.c
@@ -107,23 +107,27 @@ static void __spin_lock_debug(raw_spinlock_t *lock)
 {
 	u64 i;
 	u64 loops = loops_per_jiffy * HZ;
-	int print_once = 1;
 
-	for (;;) {
-		for (i = 0; i < loops; i++) {
-			if (arch_spin_trylock(&lock->raw_lock))
-				return;
-			__delay(1);
-		}
-		/* lockup suspected: */
-		if (print_once) {
-			print_once = 0;
-			spin_dump(lock, "lockup suspected");
+	for (i = 0; i < loops; i++) {
+		if (arch_spin_trylock(&lock->raw_lock))
+			return;
+		__delay(1);
+	}
+	/* lockup suspected: */
+	spin_dump(lock, "lockup suspected");
 #ifdef CONFIG_SMP
-			trigger_all_cpu_backtrace();
+	trigger_all_cpu_backtrace();
 #endif
-		}
-	}
+
+	/*
+	 * The trylock above was causing a livelock.  Give the lower level arch
+	 * specific lock code a chance to acquire the lock. We have already
+	 * printed a warning/backtrace at this point. The non-debug arch
+	 * specific code might actually succeed in acquiring the lock.  If it is
+	 * not successful, the end-result is the same - there is no forward
+	 * progress.
+	 */
+	arch_spin_lock(&lock->raw_lock);
 }
 
 void do_raw_spin_lock(raw_spinlock_t *lock)