linux-kernel - [tip:core/urgent] lockdep: Fix trace_hardirqs_on

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Date:	Thu, 4 Aug 2011 08:34:24 GMT
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, sergey.senozhatsky@...il.com,
	davej@...hat.com, tglx@...utronix.de, lacombar@...il.com,
	mingo@...e.hu
Subject: [tip:core/urgent] lockdep: Fix trace_hardirqs_on_caller()

Commit-ID:  7d36b26be0f3c6b86e3ab7e1539e42f3a3bc79ca
Gitweb:     http://git.kernel.org/tip/7d36b26be0f3c6b86e3ab7e1539e42f3a3bc79ca
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Tue, 26 Jul 2011 13:13:44 +0200
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 4 Aug 2011 10:17:36 +0200

lockdep: Fix trace_hardirqs_on_caller()

Commit dd4e5d3ac4a ("lockdep: Fix trace_[soft,hard]irqs_[on,off]()
recursion") made a bit of a mess of the various checks and error
conditions.

In particular it moved the check for !irqs_disabled() before the
spurious enable test, resulting in some warnings.

Reported-by: Arnaud Lacombe <lacombar@...il.com>
Reported-by: Dave Jones <davej@...hat.com>
Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/1311679697.24752.28.camel@twins
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/lockdep.c |   30 ++++++++++++++++--------------
 1 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 3956f51..74ca247 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2485,23 +2485,9 @@ static void __trace_hardirqs_on_caller(unsigned long ip)
 {
 	struct task_struct *curr = current;
 
-	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
-		return;
-
-	if (unlikely(curr->hardirqs_enabled)) {
-		/*
-		 * Neither irq nor preemption are disabled here
-		 * so this is racy by nature but losing one hit
-		 * in a stat is not a big deal.
-		 */
-		__debug_atomic_inc(redundant_hardirqs_on);
-		return;
-	}
 	/* we'll do an OFF -> ON transition: */
 	curr->hardirqs_enabled = 1;
 
-	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
-		return;
 	/*
 	 * We are going to turn hardirqs on, so set the
 	 * usage bit for all held locks:
@@ -2529,9 +2515,25 @@ void trace_hardirqs_on_caller(unsigned long ip)
 	if (unlikely(!debug_locks || current->lockdep_recursion))
 		return;
 
+	if (unlikely(current->hardirqs_enabled)) {
+		/*
+		 * Neither irq nor preemption are disabled here
+		 * so this is racy by nature but losing one hit
+		 * in a stat is not a big deal.
+		 */
+		__debug_atomic_inc(redundant_hardirqs_on);
+		return;
+	}
+
 	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
 		return;
 
+	if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
+		return;
+
+	if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
+		return;
+
 	current->lockdep_recursion = 1;
 	__trace_hardirqs_on_caller(ip);
 	current->lockdep_recursion = 0;
--
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