linux-kernel - [tip:core/locking] lockdep: fix deadlock in lockdep_trace

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Date:	Fri, 20 Mar 2009 10:26:53 GMT
From:	Peter Zijlstra <peterz@...radead.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, peterz@...radead.org, npiggin@...e.de,
	heiko.carstens@...ibm.com, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:core/locking] lockdep: fix deadlock in lockdep_trace_alloc

Commit-ID:  b0992675bc7a5eca3c6a5eeea5ed680cec09c8e7
Gitweb:     http://git.kernel.org/tip/b0992675bc7a5eca3c6a5eeea5ed680cec09c8e7
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Fri, 20 Mar 2009 11:13:20 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 20 Mar 2009 11:23:15 +0100

lockdep: fix deadlock in lockdep_trace_alloc

Heiko reported that we grab the graph lock with irqs enabled.

Fix this by providng the same wrapper as all other lockdep entry
functions have.

Reported-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Nick Piggin <npiggin@...e.de>
LKML-Reference: <1237544000.24626.52.camel@...ns>
Signed-off-by: Ingo Molnar <mingo@...e.hu>


---
 kernel/lockdep.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 77ac37f..c750038 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2257,7 +2257,7 @@ void trace_softirqs_off(unsigned long ip)
 		debug_atomic_inc(&redundant_softirqs_off);
 }
 
-void lockdep_trace_alloc(gfp_t gfp_mask)
+static void __lockdep_trace_alloc(gfp_t gfp_mask)
 {
 	struct task_struct *curr = current;
 
@@ -2282,6 +2282,20 @@ void lockdep_trace_alloc(gfp_t gfp_mask)
 	mark_held_locks(curr, RECLAIM_FS);
 }
 
+void lockdep_trace_alloc(gfp_t gfp_mask)
+{
+	unsigned long flags;
+
+	if (unlikely(current->lockdep_recursion))
+		return;
+
+	raw_local_irq_save(flags);
+	current->lockdep_recursion = 1;
+	__lockdep_trace_alloc(gfp_mask);
+	current->lockdep_recursion = 0;
+	raw_local_irq_restore(flags);
+}
+
 static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
 {
 	/*
--
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