crypto: cryptd - Use refcount_t for refcount

Reference counters are preferred to use refcount_t instead of
atomic_t.
This is because the implementation of refcount_t can prevent
overflows and detect possible use-after-free.
So convert atomic_t ref counters to refcount_t.

Signed-off-by: Chuhong Yuan <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

crypto/cryptd.c

···
 #include <crypto/internal/aead.h>
 #include <crypto/internal/skcipher.h>
 #include <crypto/cryptd.h>
-#include <linux/atomic.h>
+#include <linux/refcount.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
···
 };
 
 struct cryptd_skcipher_ctx {
-	atomic_t refcnt;
+	refcount_t refcnt;
 	struct crypto_sync_skcipher *child;
 };
 
···
 };
 
 struct cryptd_hash_ctx {
-	atomic_t refcnt;
+	refcount_t refcnt;
 	struct crypto_shash *child;
 };
 
···
 };
 
 struct cryptd_aead_ctx {
-	atomic_t refcnt;
+	refcount_t refcnt;
 	struct crypto_aead *child;
 };
 
···
 {
 	int cpu, err;
 	struct cryptd_cpu_queue *cpu_queue;
-	atomic_t *refcnt;
+	refcount_t *refcnt;
 
 	cpu = get_cpu();
 	cpu_queue = this_cpu_ptr(queue->cpu_queue);
···
 
 	queue_work_on(cpu, cryptd_wq, &cpu_queue->work);
 
-	if (!atomic_read(refcnt))
+	if (!refcount_read(refcnt))
 		goto out_put_cpu;
 
-	atomic_inc(refcnt);
+	refcount_inc(refcnt);
 
 out_put_cpu:
 	put_cpu();
···
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(tfm);
 	struct cryptd_skcipher_request_ctx *rctx = skcipher_request_ctx(req);
-	int refcnt = atomic_read(&ctx->refcnt);
+	int refcnt = refcount_read(&ctx->refcnt);
 
 	local_bh_disable();
 	rctx->complete(&req->base, err);
 	local_bh_enable();
 
-	if (err != -EINPROGRESS && refcnt && atomic_dec_and_test(&ctx->refcnt))
+	if (err != -EINPROGRESS && refcnt && refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_skcipher(tfm);
 }
 
···
 	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
 	struct cryptd_hash_ctx *ctx = crypto_ahash_ctx(tfm);
 	struct cryptd_hash_request_ctx *rctx = ahash_request_ctx(req);
-	int refcnt = atomic_read(&ctx->refcnt);
+	int refcnt = refcount_read(&ctx->refcnt);
 
 	local_bh_disable();
 	rctx->complete(&req->base, err);
 	local_bh_enable();
 
-	if (err != -EINPROGRESS && refcnt && atomic_dec_and_test(&ctx->refcnt))
+	if (err != -EINPROGRESS && refcnt && refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_ahash(tfm);
 }
 
···
 
 out:
 	ctx = crypto_aead_ctx(tfm);
-	refcnt = atomic_read(&ctx->refcnt);
+	refcnt = refcount_read(&ctx->refcnt);
 
 	local_bh_disable();
 	compl(&req->base, err);
 	local_bh_enable();
 
-	if (err != -EINPROGRESS && refcnt && atomic_dec_and_test(&ctx->refcnt))
+	if (err != -EINPROGRESS && refcnt && refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_aead(tfm);
 }
 
···
 	}
 
 	ctx = crypto_skcipher_ctx(tfm);
-	atomic_set(&ctx->refcnt, 1);
+	refcount_set(&ctx->refcnt, 1);
 
 	return container_of(tfm, struct cryptd_skcipher, base);
 }
···
 {
 	struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(&tfm->base);
 
-	return atomic_read(&ctx->refcnt) - 1;
+	return refcount_read(&ctx->refcnt) - 1;
 }
 EXPORT_SYMBOL_GPL(cryptd_skcipher_queued);
 
···
 {
 	struct cryptd_skcipher_ctx *ctx = crypto_skcipher_ctx(&tfm->base);
 
-	if (atomic_dec_and_test(&ctx->refcnt))
+	if (refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_skcipher(&tfm->base);
 }
 EXPORT_SYMBOL_GPL(cryptd_free_skcipher);
···
 	}
 
 	ctx = crypto_ahash_ctx(tfm);
-	atomic_set(&ctx->refcnt, 1);
+	refcount_set(&ctx->refcnt, 1);
 
 	return __cryptd_ahash_cast(tfm);
 }
···
 {
 	struct cryptd_hash_ctx *ctx = crypto_ahash_ctx(&tfm->base);
 
-	return atomic_read(&ctx->refcnt) - 1;
+	return refcount_read(&ctx->refcnt) - 1;
 }
 EXPORT_SYMBOL_GPL(cryptd_ahash_queued);
 
···
 {
 	struct cryptd_hash_ctx *ctx = crypto_ahash_ctx(&tfm->base);
 
-	if (atomic_dec_and_test(&ctx->refcnt))
+	if (refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_ahash(&tfm->base);
 }
 EXPORT_SYMBOL_GPL(cryptd_free_ahash);
···
 	}
 
 	ctx = crypto_aead_ctx(tfm);
-	atomic_set(&ctx->refcnt, 1);
+	refcount_set(&ctx->refcnt, 1);
 
 	return __cryptd_aead_cast(tfm);
 }
···
 {
 	struct cryptd_aead_ctx *ctx = crypto_aead_ctx(&tfm->base);
 
-	return atomic_read(&ctx->refcnt) - 1;
+	return refcount_read(&ctx->refcnt) - 1;
 }
 EXPORT_SYMBOL_GPL(cryptd_aead_queued);
 
···
 {
 	struct cryptd_aead_ctx *ctx = crypto_aead_ctx(&tfm->base);
 
-	if (atomic_dec_and_test(&ctx->refcnt))
+	if (refcount_dec_and_test(&ctx->refcnt))
 		crypto_free_aead(&tfm->base);
 }
 EXPORT_SYMBOL_GPL(cryptd_free_aead);