[PATCH] devcgroup: avoid using cgroup_lock

Li Zefan
2009-03-12T01:48:23Z

There is nothing special that has to be protected by cgroup_lock,
so introduce devcgroup_mtuex for it's own use.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
security/device_cgroup.c | 21 +++++++++++++--------
1 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 3aacd0f..5fda7df 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -11,6 +11,7 @@
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
+#include <linux/mutex.h>

#define ACC_MKNOD 1
#define ACC_READ 2
@@ -21,9 +22,11 @@
#define DEV_CHAR 2
#define DEV_ALL 4 /* this represents all devices */

+static DEFINE_MUTEX(devcgroup_mutex);
+
/*
* whitelist locking rules:
- * hold cgroup_lock() for update/read.
+ * hold devcgroup_mutex for update/read.
* hold rcu_read_lock() for read.
*/

@@ -67,7 +70,7 @@ static int devcgroup_can_attach(struct cgroup_subsys *ss,
}

/*
- * called under cgroup_lock()
+ * called under devcgroup_mutex
*/
static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig)
{
@@ -92,7 +95,7 @@ free_and_exit:

/* Stupid prototype - don't bother combining existing entries */
/*
- * called under cgroup_lock()
+ * called under devcgroup_mutex
*/
static int dev_whitelist_add(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
@@ -130,7 +133,7 @@ static void whitelist_item_free(struct rcu_head *rcu)
}

/*
- * called under cgroup_lock()
+ * called under devcgroup_mutex
*/
static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup,
struct dev_whitelist_item *wh)
@@ -185,8 +188,10 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss,
list_add(&wh->list, &dev_cgroup->whitelist);
} else {
parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
+ mutex_lock(&devcgroup_mutex);
ret = dev_whitelist_copy(&dev_cgroup->whitelist,
&parent_dev_cgroup->whitelist);
+ mutex_unlock(&devcgroup_mutex);
if (ret) {
kfree(dev_cgroup);
return ERR_PTR(ret);
@@ -273,7 +278,7 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
* does the access granted to dev_cgroup c contain the access
* requested in whitelist item refwh.
* return 1 if yes, 0 if no.
- * call with c->lock held
+ * call with devcgroup_mutex held
*/
static int may_access_whitelist(struct dev_cgroup *c,
struct dev_whitelist_item *refwh)
@@ -426,11 +431,11 @@ static int devcgroup_access_write(struct cgroup *cgrp, struct cftype *cft,
const char *buffer)
{
int retval;
- if (!cgroup_lock_live_group(cgrp))
- return -ENODEV;
+
+ mutex_lock(&devcgroup_mutex);
retval = devcgroup_update_access(cgroup_to_devcgroup(cgrp),
cft->private, buffer);
- cgroup_unlock();
+ mutex_unlock(&devcgroup_mutex);
return retval;
}

--
1.5.4.rc3