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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>
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/*
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* Copyright (C) 2012 Red Hat. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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struct rcu_string {
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struct rcu_head rcu;
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char str[0];
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};
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static inline struct rcu_string *rcu_string_strdup(const char *src, gfp_t mask)
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{
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size_t len = strlen(src) + 1;
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struct rcu_string *ret = kzalloc(sizeof(struct rcu_string) +
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(len * sizeof(char)), mask);
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if (!ret)
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return ret;
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strncpy(ret->str, src, len);
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return ret;
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}
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static inline void rcu_string_free(struct rcu_string *str)
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{
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if (str)
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kfree_rcu(str, rcu);
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}
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#define printk_in_rcu(fmt, ...) do { \
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rcu_read_lock(); \
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printk(fmt, __VA_ARGS__); \
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rcu_read_unlock(); \
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} while (0)
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#define printk_ratelimited_in_rcu(fmt, ...) do { \
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rcu_read_lock(); \
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printk_ratelimited(fmt, __VA_ARGS__); \
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rcu_read_unlock(); \
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} while (0)
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#define rcu_str_deref(rcu_str) ({ \
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struct rcu_string *__str = rcu_dereference(rcu_str); \
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__str->str; \
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})
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