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Commit b4046f00 authored by Li Zefan's avatar Li Zefan Committed by Linus Torvalds
Browse files

devcgroup: avoid using cgroup_lock 



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

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d969fbe6

security/device_cgroup.c

+13 −8
Original line number Diff line number Diff line
@@ -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 @@ static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig) 


/* 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;

}