mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 17:08:10 +00:00
606686eeac
Al pointed out that we can just toss out the old name on a device and add a new one arbitrarily, so anybody who uses device->name in printk could possibly use free'd memory. Instead of adding locking around all of this he suggested doing it with RCU, so I've introduced a struct rcu_string that does just that and have gone through and protected all accesses to device->name that aren't under the uuid_mutex with rcu_read_lock(). This protects us and I will use it for dealing with removing the device that we used to mount the file system in a later patch. Thanks, Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Josef Bacik <josef@redhat.com>
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/*
|
|
* Copyright (C) 2012 Red Hat. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public
|
|
* License v2 as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public
|
|
* License along with this program; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 021110-1307, USA.
|
|
*/
|
|
|
|
struct rcu_string {
|
|
struct rcu_head rcu;
|
|
char str[0];
|
|
};
|
|
|
|
static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask)
|
|
{
|
|
size_t len = strlen(src) + 1;
|
|
struct rcu_string *ret = kzalloc(sizeof(struct rcu_string) +
|
|
(len * sizeof(char)), mask);
|
|
if (!ret)
|
|
return ret;
|
|
strncpy(ret->str, src, len);
|
|
return ret;
|
|
}
|
|
|
|
static inline void rcu_string_free(struct rcu_string *str)
|
|
{
|
|
if (str)
|
|
kfree_rcu(str, rcu);
|
|
}
|
|
|
|
#define printk_in_rcu(fmt, ...) do { \
|
|
rcu_read_lock(); \
|
|
printk(fmt, __VA_ARGS__); \
|
|
rcu_read_unlock(); \
|
|
} while (0)
|
|
|
|
#define printk_ratelimited_in_rcu(fmt, ...) do { \
|
|
rcu_read_lock(); \
|
|
printk_ratelimited(fmt, __VA_ARGS__); \
|
|
rcu_read_unlock(); \
|
|
} while (0)
|
|
|
|
#define rcu_str_deref(rcu_str) ({ \
|
|
struct rcu_string *__str = rcu_dereference(rcu_str); \
|
|
__str->str; \
|
|
})
|