CRYPTO: Octeon: always disable preemption when using crypto engine

Always disable preemption on behalf of the drivers when crypto engine
is taken into use. This will simplify the usage.
Signed-off-by: NAaro Koskinen <aaro.koskinen@iki.fi>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9494/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/cavium-octeon/crypto/octeon-crypto.c

@@ -17,7 +17,7 @@
  * crypto operations in calls to octeon_crypto_enable/disable in order to make
  * sure the state of COP2 isn't corrupted if userspace is also performing
  * hardware crypto operations. Allocate the state parameter on the stack.
- * Preemption must be disabled to prevent context switches.
+ * Returns with preemption disabled.
  *
  * @state: Pointer to state structure to store current COP2 state in.
  *
@@ -28,6 +28,7 @@ unsigned long octeon_crypto_enable(struct octeon_cop2_state *state)
 	int status;
 	unsigned long flags;
 
+	preempt_disable();
 	local_irq_save(flags);
 	status = read_c0_status();
 	write_c0_status(status | ST0_CU2);
@@ -62,5 +63,6 @@ void octeon_crypto_disable(struct octeon_cop2_state *state,
 	else
 		write_c0_status(read_c0_status() & ~ST0_CU2);
 	local_irq_restore(flags);
+	preempt_enable();
 }
 EXPORT_SYMBOL_GPL(octeon_crypto_disable);

arch/mips/cavium-octeon/crypto/octeon-md5.c

@@ -97,7 +97,6 @@ static int octeon_md5_update(struct shash_desc *desc, const u8 *data,
 	memcpy((char *)mctx->block + (sizeof(mctx->block) - avail), data,
 	       avail);
 
-	preempt_disable();
 	flags = octeon_crypto_enable(&state);
 	octeon_md5_store_hash(mctx);
 
@@ -113,7 +112,6 @@ static int octeon_md5_update(struct shash_desc *desc, const u8 *data,
 
 	octeon_md5_read_hash(mctx);
 	octeon_crypto_disable(&state, flags);
-	preempt_enable();
 
 	memcpy(mctx->block, data, len);
 
@@ -131,7 +129,6 @@ static int octeon_md5_final(struct shash_desc *desc, u8 *out)
 
 	*p++ = 0x80;
 
-	preempt_disable();
 	flags = octeon_crypto_enable(&state);
 	octeon_md5_store_hash(mctx);
 
@@ -149,7 +146,6 @@ static int octeon_md5_final(struct shash_desc *desc, u8 *out)
 
 	octeon_md5_read_hash(mctx);
 	octeon_crypto_disable(&state, flags);
-	preempt_enable();
 
 	memcpy(out, mctx->hash, sizeof(mctx->hash));
 	memset(mctx, 0, sizeof(*mctx));