[PATCH] [Natty SRU] UBUNTU: SAUCE: fix yama_ptracer_del lockdep warning(v1)

[Ming Lei]

From a3bea763772d6f0f672b76f26dd6152d6d40812f Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei at canonical.com>
Date: Wed, 29 Jun 2011 19:06:25 +0800
Subject: [PATCH] [Natty SRU] UBUNTU: SAUCE: fix yama_ptracer_del lockdep warning(v1)

yama_ptracer_del can be called in softirq context, so
ptracer_relations_lock may be held in softirq context.

This patch replaces spin_[un]lock with spin_[un]lock_bh for
&ptracer_relations_lock to fix reported lockdep warning and
avoid possible dealock.

SRU Justification:

Impact:
	- lockdep warning is triggered if lockdep config options are
	  enabled
	- probably deadlock can be produced in yama_ptracer_del path

Fix:
	- After applying the patch, lockdep warning is fixefd

BugLink: http://bugs.launchpad.net/bugs/791019

Signed-off-by: Ming Lei <ming.lei at canonical.com>
---
 security/yama/yama_lsm.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 7c3591a..b200e33 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -46,7 +46,7 @@ static int yama_ptracer_add(struct task_struct *tracer,
 	struct ptrace_relation *entry, *relation = NULL;
 
 	added = kmalloc(sizeof(*added), GFP_KERNEL);
-	spin_lock(&ptracer_relations_lock);
+	spin_lock_bh(&ptracer_relations_lock);
 	list_for_each_entry(entry, &ptracer_relations, node)
 		if (entry->tracee == tracee) {
 			relation = entry;
@@ -64,7 +64,7 @@ static int yama_ptracer_add(struct task_struct *tracer,
 	relation->tracer = tracer;
 
 unlock_out:
-	spin_unlock(&ptracer_relations_lock);
+	spin_unlock_bh(&ptracer_relations_lock);
 	if (added && added != relation)
 		kfree(added);
 
@@ -82,7 +82,7 @@ static void yama_ptracer_del(struct task_struct *tracer,
 	struct ptrace_relation *relation;
 	struct list_head *list, *safe;
 
-	spin_lock(&ptracer_relations_lock);
+	spin_lock_bh(&ptracer_relations_lock);
 	list_for_each_safe(list, safe, &ptracer_relations) {
 		relation = list_entry(list, struct ptrace_relation, node);
 		if (relation->tracee == tracee ||
@@ -91,7 +91,7 @@ static void yama_ptracer_del(struct task_struct *tracer,
 			kfree(relation);
 		}
 	}
-	spin_unlock(&ptracer_relations_lock);
+	spin_unlock_bh(&ptracer_relations_lock);
 }
 
 /**
@@ -205,7 +205,7 @@ static int ptracer_exception_found(struct task_struct *tracer,
 	struct ptrace_relation *relation;
 	struct task_struct *parent = NULL;
 
-	spin_lock(&ptracer_relations_lock);
+	spin_lock_bh(&ptracer_relations_lock);
 
 	rcu_read_lock();
 	read_lock(&tasklist_lock);
@@ -221,7 +221,7 @@ static int ptracer_exception_found(struct task_struct *tracer,
 
 	if (task_is_descendant(parent, tracer))
 		rc = 1;
-	spin_unlock(&ptracer_relations_lock);
+	spin_unlock_bh(&ptracer_relations_lock);
 
 	return rc;
 }
-- 
1.7.4.1



--
Ming Lei