[PATCH 6.1 1/3] Revert "crypto: jitterentropy - replace long-held spinlock with mutex"

[Eric Biggers <ebiggers@kernel.org>]

This reverts commit 21de77d06f6b540e870e64ef5ff56be4eb8ba08f.

This is needed to cleanly revert commit fc659f1a6903 ("crypto: jitter -
replace LFSR with SHA3-256").  It will be reapplied.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 crypto/jitterentropy-kcapi.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/crypto/jitterentropy-kcapi.c b/crypto/jitterentropy-kcapi.c
index 74d5c8da0e8ab..4b50cbc8a2faf 100644
--- a/crypto/jitterentropy-kcapi.c
+++ b/crypto/jitterentropy-kcapi.c
@@ -42,7 +42,6 @@
 #include <linux/fips.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/time.h>
 #include <crypto/internal/rng.h>
@@ -181,7 +180,7 @@ int jent_read_random_block(void *hash_state, char *dst, unsigned int dst_len)
  ***************************************************************************/
 
 struct jitterentropy {
-	struct mutex jent_lock;
+	spinlock_t jent_lock;
 	struct rand_data *entropy_collector;
 	struct crypto_shash *tfm;
 	struct shash_desc *sdesc;
@@ -191,7 +190,7 @@ static void jent_kcapi_cleanup(struct crypto_tfm *tfm)
 {
 	struct jitterentropy *rng = crypto_tfm_ctx(tfm);
 
-	mutex_lock(&rng->jent_lock);
+	spin_lock(&rng->jent_lock);
 
 	if (rng->sdesc) {
 		shash_desc_zero(rng->sdesc);
@@ -206,7 +205,7 @@ static void jent_kcapi_cleanup(struct crypto_tfm *tfm)
 	if (rng->entropy_collector)
 		jent_entropy_collector_free(rng->entropy_collector);
 	rng->entropy_collector = NULL;
-	mutex_unlock(&rng->jent_lock);
+	spin_unlock(&rng->jent_lock);
 }
 
 static int jent_kcapi_init(struct crypto_tfm *tfm)
@@ -216,7 +215,7 @@ static int jent_kcapi_init(struct crypto_tfm *tfm)
 	struct shash_desc *sdesc;
 	int size, ret = 0;
 
-	mutex_init(&rng->jent_lock);
+	spin_lock_init(&rng->jent_lock);
 
 	/*
 	 * Use SHA3-256 as conditioner. We allocate only the generic
@@ -251,6 +250,7 @@ static int jent_kcapi_init(struct crypto_tfm *tfm)
 		goto err;
 	}
 
+	spin_lock_init(&rng->jent_lock);
 	return 0;
 
 err:
@@ -265,7 +265,7 @@ static int jent_kcapi_random(struct crypto_rng *tfm,
 	struct jitterentropy *rng = crypto_rng_ctx(tfm);
 	int ret = 0;
 
-	mutex_lock(&rng->jent_lock);
+	spin_lock(&rng->jent_lock);
 
 	ret = jent_read_entropy(rng->entropy_collector, rdata, dlen);
 
@@ -291,7 +291,7 @@ static int jent_kcapi_random(struct crypto_rng *tfm,
 		ret = -EINVAL;
 	}
 
-	mutex_unlock(&rng->jent_lock);
+	spin_unlock(&rng->jent_lock);
 
 	return ret;
 }
-- 
2.56.0