UBUNTU: SAUCE: fix yama_ptracer_del lockdep warning

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.

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

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Acked-by: Tim Gardner <tim.gardner@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 7c3591a..b200e33 100644 (file)
--- 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;
 }