From 6521f30273fbec65146a0f16de74b7b402b0f7b0 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Sun, 6 Aug 2006 20:28:44 +1000 Subject: [PATCH] [CRYPTO] api: Add crypto_alg reference counting 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 Signed-off-by: David S. Miller --- crypto/api.c | 32 ++++++++++++++++++++++++++------ crypto/proc.c | 3 +++ include/linux/crypto.h | 3 +++ 3 files changed, 32 insertions(+), 6 deletions(-) diff --git a/crypto/api.c b/crypto/api.c index 8c2743a05f..5994a58ef9 100644 --- a/crypto/api.c +++ b/crypto/api.c @@ -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_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 inline void crypto_mod_put(struct crypto_alg *alg) +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) diff --git a/crypto/proc.c b/crypto/proc.c index c0a5dd7ce2..8543b7a157 100644 --- a/crypto/proc.c +++ b/crypto/proc.c @@ -12,6 +12,8 @@ * any later version. * */ + +#include #include #include #include @@ -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: diff --git a/include/linux/crypto.h b/include/linux/crypto.h index cb1e6631b1..7f57ff8ec9 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -17,6 +17,7 @@ #ifndef _LINUX_CRYPTO_H #define _LINUX_CRYPTO_H +#include #include #include #include @@ -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; }; -- 2.39.5