diff options
| -rw-r--r-- | security/device_cgroup.c | 34 |
1 files changed, 5 insertions, 29 deletions
diff --git a/security/device_cgroup.c b/security/device_cgroup.c index d5c15a7c67c3..5ba78701adc3 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -1,5 +1,5 @@ /* - * dev_cgroup.c - device cgroup subsystem + * device_cgroup.c - device cgroup subsystem * * Copyright 2007 IBM Corp */ @@ -10,6 +10,7 @@ #include <linux/list.h> #include <linux/uaccess.h> #include <linux/seq_file.h> +#include <linux/rcupdate.h> #define ACC_MKNOD 1 #define ACC_READ 2 @@ -22,18 +23,8 @@ /* * whitelist locking rules: - * cgroup_lock() cannot be taken under dev_cgroup->lock. - * dev_cgroup->lock can be taken with or without cgroup_lock(). - * - * modifications always require cgroup_lock - * modifications to a list which is visible require the - * dev_cgroup->lock *and* cgroup_lock() - * walking the list requires dev_cgroup->lock or cgroup_lock(). - * - * reasoning: dev_whitelist_copy() needs to kmalloc, so needs - * a mutex, which the cgroup_lock() is. Since modifying - * a visible list requires both locks, either lock can be - * taken for walking the list. + * hold cgroup_lock() for update/read. + * hold rcu_read_lock() for read. */ struct dev_whitelist_item { @@ -47,7 +38,6 @@ struct dev_whitelist_item { struct dev_cgroup { struct cgroup_subsys_state css; struct list_head whitelist; - spinlock_t lock; }; static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s) @@ -103,7 +93,6 @@ free_and_exit: /* Stupid prototype - don't bother combining existing entries */ /* * called under cgroup_lock() - * since the list is visible to other tasks, we need the spinlock also */ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, struct dev_whitelist_item *wh) @@ -114,7 +103,6 @@ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, if (!whcopy) return -ENOMEM; - spin_lock(&dev_cgroup->lock); list_for_each_entry(walk, &dev_cgroup->whitelist, list) { if (walk->type != wh->type) continue; @@ -130,7 +118,6 @@ static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, if (whcopy != NULL) list_add_tail_rcu(&whcopy->list, &dev_cgroup->whitelist); - spin_unlock(&dev_cgroup->lock); return 0; } @@ -144,14 +131,12 @@ static void whitelist_item_free(struct rcu_head *rcu) /* * called under cgroup_lock() - * since the list is visible to other tasks, we need the spinlock also */ static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup, struct dev_whitelist_item *wh) { struct dev_whitelist_item *walk, *tmp; - spin_lock(&dev_cgroup->lock); list_for_each_entry_safe(walk, tmp, &dev_cgroup->whitelist, list) { if (walk->type == DEV_ALL) goto remove; @@ -169,7 +154,6 @@ remove: call_rcu(&walk->rcu, whitelist_item_free); } } - spin_unlock(&dev_cgroup->lock); } /* @@ -209,7 +193,6 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss, } } - spin_lock_init(&dev_cgroup->lock); return &dev_cgroup->css; } @@ -325,15 +308,11 @@ static int parent_has_perm(struct dev_cgroup *childcg, { struct cgroup *pcg = childcg->css.cgroup->parent; struct dev_cgroup *parent; - int ret; if (!pcg) return 1; parent = cgroup_to_devcgroup(pcg); - spin_lock(&parent->lock); - ret = may_access_whitelist(parent, wh); - spin_unlock(&parent->lock); - return ret; + return may_access_whitelist(parent, wh); } /* @@ -352,7 +331,6 @@ static int parent_has_perm(struct dev_cgroup *childcg, static int devcgroup_update_access(struct dev_cgroup *devcgroup, int filetype, const char *buffer) { - struct dev_cgroup *cur_devcgroup; const char *b; char *endp; int count; @@ -361,8 +339,6 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, if (!capable(CAP_SYS_ADMIN)) return -EPERM; - cur_devcgroup = task_devcgroup(current); - memset(&wh, 0, sizeof(wh)); b = buffer; |