From 1d32d09a150e52c62a7cec3ac193752208394ceb Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 26 Jul 2009 18:39:41 +0200
Subject: [PATCH] sched: Add lock_count to task struct

commit 53e9ba175098c8f13e2cc0a45f3b586a22a4ffd3 in tip.

Debugging interface.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
 include/linux/sched.h |   20 ++++++++++++++++++++
 kernel/fork.c         |    6 ++++++
 2 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 304c8c8..0f0cc03 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1414,6 +1414,26 @@ struct task_struct {
 	gfp_t lockdep_reclaim_gfp;
 #endif
 
+/* realtime bits */
+
+#define MAX_PREEMPT_TRACE 25
+#define MAX_LOCK_STACK	MAX_PREEMPT_TRACE
+#ifdef CONFIG_DEBUG_PREEMPT
+	int lock_count;
+# ifdef CONFIG_PREEMPT_RT
+	struct rt_mutex *owned_lock[MAX_LOCK_STACK];
+# endif
+#endif
+#ifdef CONFIG_DETECT_SOFTLOCKUP
+	unsigned long	softlockup_count; /* Count to keep track how long the
+					   *  thread is in the kernel without
+					   *  sleeping.
+					   */
+#endif
+#ifdef CONFIG_DEBUG_RT_MUTEXES
+	void *last_kernel_lock;
+#endif
+
 /* journalling filesystem info */
 	void *journal_info;
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 1a3f641..f496dcf 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -920,6 +920,9 @@ static void rt_mutex_init_task(struct task_struct *p)
 #ifdef CONFIG_RT_MUTEXES
 	plist_head_init_raw(&p->pi_waiters, &p->pi_lock);
 	p->pi_blocked_on = NULL;
+# ifdef CONFIG_DEBUG_RT_MUTEXES
+	p->last_kernel_lock = NULL;
+# endif
 #endif
 }
 
@@ -1145,6 +1148,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
 	if (retval)
 		goto bad_fork_cleanup_io;
+#ifdef CONFIG_DEBUG_PREEMPT
+	p->lock_count = 0;
+#endif
 
 	if (pid != &init_struct_pid) {
 		retval = -ENOMEM;
-- 
1.7.0.4