linux-kernel - [PATCH 2.6.19-rc2-git3] lockdep: internal locking fixes

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Message-ID: <20061020061234.GA1898@ff.dom.local>
Date:	Fri, 20 Oct 2006 08:12:34 +0200
From:	Jarek Poplawski <jarkao2@...pl>
To:	linux-kernel@...r.kernel.org
Cc:	mingo@...e.hu
Subject: [PATCH 2.6.19-rc2-git3] lockdep: internal locking fixes

Hello,

Here are mainly some lockdep returns with 0 with unlocking fixes. 

Regards,
Jarek P.

PS: if there will be any questions after 3PM EST
I'll be back on monday. 


Signed-off-by: Jarek Poplawski <jarkao2@...pl>
---

diff -Nurp linux-2.6.19-rc2-git3-/kernel/lockdep.c linux-2.6.19-rc2-git3/kernel/lockdep.c
--- linux-2.6.19-rc2-git3-/kernel/lockdep.c	2006-10-19 18:41:00.000000000 +0200
+++ linux-2.6.19-rc2-git3/kernel/lockdep.c	2006-10-19 23:27:51.000000000 +0200
@@ -227,9 +227,9 @@ static int save_trace(struct stack_trace
 
 	trace->skip = 3;
 	trace->all_contexts = 0;
-
-	/* Make sure to not recurse in case the the unwinder needs to tak
-e	   locks. */
+	/*
+	 * Make sure to not recurse in case the unwinder needs to take locks.
+	 */
 	lockdep_off();
 	save_stack_trace(trace, NULL);
 	lockdep_on();
@@ -237,8 +237,10 @@ e	   locks. */
 	trace->max_entries = trace->nr_entries;
 
 	nr_stack_trace_entries += trace->nr_entries;
-	if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES))
+	if (DEBUG_LOCKS_WARN_ON(nr_stack_trace_entries > MAX_STACK_TRACE_ENTRIES)) {
+		__raw_spin_unlock(&hash_lock);
 		return 0;
+	}
 
 	if (nr_stack_trace_entries == MAX_STACK_TRACE_ENTRIES) {
 		__raw_spin_unlock(&hash_lock);
@@ -474,7 +476,8 @@ static int add_lock_to_list(struct lock_
 		return 0;
 
 	entry->class = this;
-	save_trace(&entry->trace);
+	if (!save_trace(&entry->trace))
+		return 0;
 
 	/*
 	 * Since we never remove from the dependency list, the list can
@@ -563,7 +566,10 @@ static noinline int print_circular_bug_t
 		return 0;
 
 	this.class = check_source->class;
-	save_trace(&this.trace);
+	/* hash_lock unlocked by the header */
+	__raw_spin_lock(&hash_lock);
+	if (!save_trace(&this.trace))
+		return 0;
 	print_circular_bug_entry(&this, 0);
 
 	printk("\nother info that might help us debug this:\n\n");
@@ -959,6 +965,9 @@ check_prev_add(struct task_struct *curr,
 	}
 
 	/*
+	 * Return value of 2 signals 'dependency already added',
+	 * in that case we dont have to add the backlink either.
+	 *
 	 * Ok, all validations passed, add the new lock
 	 * to the previous lock's dependency list:
 	 */
@@ -966,15 +975,10 @@ check_prev_add(struct task_struct *curr,
 			       &prev->class->locks_after, next->acquire_ip);
 	if (!ret)
 		return 0;
-	/*
-	 * Return value of 2 signals 'dependency already added',
-	 * in that case we dont have to add the backlink either.
-	 */
-	if (ret == 2)
-		return 2;
 	ret = add_lock_to_list(next->class, prev->class,
 			       &next->class->locks_before, next->acquire_ip);
-
+	if (!ret)
+		return 0;
 	/*
 	 * Debugging printouts:
 	 */
-
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