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[CRYPTO] api: Add crypto_alg reference counting

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Up until now we've relied on module reference counting to ensure that the
crypto_alg structures don't disappear from under us.  This was good enough
as long as each crypto_alg came from exactly one module.

However, with parameterised crypto algorithms a crypto_alg object may need
two or more modules to operate.  This means that we need to count the
references to the crypto_alg object directly.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2006-08-06 20:28:44 +10:00
parent 72fa491912
commit 6521f30273
3 changed files with 32 additions and 6 deletions
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32
crypto/api.c
View file

@ -29,13 +29,26 @@
LIST_HEAD(crypto_alg_list);
DECLARE_RWSEM(crypto_alg_sem);
static inline int crypto_mod_get(struct crypto_alg *alg)
static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
{
return try_module_get(alg->cra_module);
atomic_inc(&alg->cra_refcnt);
return alg;
}
static inline void crypto_mod_put(struct crypto_alg *alg)
static inline void crypto_alg_put(struct crypto_alg *alg)
{
if (atomic_dec_and_test(&alg->cra_refcnt) && alg->cra_destroy)
alg->cra_destroy(alg);
}
static struct crypto_alg *crypto_mod_get(struct crypto_alg *alg)
{
return try_module_get(alg->cra_module) ? crypto_alg_get(alg) : NULL;
}
static void crypto_mod_put(struct crypto_alg *alg)
{
crypto_alg_put(alg);
module_put(alg->cra_module);
}
@ -274,6 +287,7 @@ int crypto_register_alg(struct crypto_alg *alg)
}
list_add(&alg->cra_list, &crypto_alg_list);
atomic_set(&alg->cra_refcnt, 1);
out:
up_write(&crypto_alg_sem);
return ret;
@ -284,8 +298,6 @@ int crypto_unregister_alg(struct crypto_alg *alg)
int ret = -ENOENT;
struct crypto_alg *q;
BUG_ON(!alg->cra_module);
down_write(&crypto_alg_sem);
list_for_each_entry(q, &crypto_alg_list, cra_list) {
if (alg == q) {
@ -296,7 +308,15 @@ int crypto_unregister_alg(struct crypto_alg *alg)
}
out:
up_write(&crypto_alg_sem);
return ret;
if (ret)
return ret;
BUG_ON(atomic_read(&alg->cra_refcnt) != 1);
if (alg->cra_destroy)
alg->cra_destroy(alg);
return 0;
}
int crypto_alg_available(const char *name, u32 flags)

3
crypto/proc.c
View file

@ -12,6 +12,8 @@
* any later version.
*
*/
#include <asm/atomic.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/rwsem.h>
@ -54,6 +56,7 @@ static int c_show(struct seq_file *m, void *p)
seq_printf(m, "driver : %s\n", alg->cra_driver_name);
seq_printf(m, "module : %s\n", module_name(alg->cra_module));
seq_printf(m, "priority : %d\n", alg->cra_priority);
seq_printf(m, "refcnt : %d\n", atomic_read(&alg->cra_refcnt));
switch (alg->cra_flags & CRYPTO_ALG_TYPE_MASK) {
case CRYPTO_ALG_TYPE_CIPHER:

3
include/linux/crypto.h
View file

@ -17,6 +17,7 @@
#ifndef _LINUX_CRYPTO_H
#define _LINUX_CRYPTO_H
#include <asm/atomic.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
@ -148,6 +149,7 @@ struct crypto_alg {
unsigned int cra_alignmask;
int cra_priority;
atomic_t cra_refcnt;
char cra_name[CRYPTO_MAX_ALG_NAME];
char cra_driver_name[CRYPTO_MAX_ALG_NAME];
@ -160,6 +162,7 @@ struct crypto_alg {
int (*cra_init)(struct crypto_tfm *tfm);
void (*cra_exit)(struct crypto_tfm *tfm);
void (*cra_destroy)(struct crypto_alg *alg);
struct module *cra_module;
};