[PATCH] crypto: ccp: Use scoped guard for mutex

[PATCH] crypto: ccp: Use scoped guard for mutex

[Mario Limonciello]

From: Mario Limonciello <mario.limonciello@amd.com>

Using a scoped guard simplifies the cleanup handling.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
---
 drivers/crypto/ccp/dbc.c | 48 +++++++++++++++-------------------------
 1 file changed, 18 insertions(+), 30 deletions(-)

diff --git a/drivers/crypto/ccp/dbc.c b/drivers/crypto/ccp/dbc.c
index 5b105a23f6997..3617e6eabab14 100644
--- a/drivers/crypto/ccp/dbc.c
+++ b/drivers/crypto/ccp/dbc.c
@@ -7,6 +7,8 @@
  * Author: Mario Limonciello <mario.limonciello@amd.com>
  */
 
+#include <linux/mutex.h>
+
 #include "dbc.h"
 
 #define DBC_DEFAULT_TIMEOUT		(10 * MSEC_PER_SEC)
@@ -137,62 +139,48 @@ static long dbc_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return -ENODEV;
 	dbc_dev = psp_master->dbc_data;
 
-	mutex_lock(&dbc_dev->ioctl_mutex);
+	guard(mutex)(&dbc_dev->ioctl_mutex);
 
 	switch (cmd) {
 	case DBCIOCNONCE:
-		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_nonce))) {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_nonce)))
+			return -EFAULT;
 
 		ret = send_dbc_nonce(dbc_dev);
 		if (ret)
-			goto unlock;
+			return ret;
 
-		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_nonce))) {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_nonce)))
+			return -EFAULT;
 		break;
 	case DBCIOCUID:
-		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_setuid))) {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_setuid)))
+			return -EFAULT;
 
 		*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_setuid);
 		ret = send_dbc_cmd(dbc_dev, PSP_DYNAMIC_BOOST_SET_UID);
 		if (ret)
-			goto unlock;
+			return ret;
 
-		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_setuid))) {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_setuid)))
+			return -EFAULT;
 		break;
 	case DBCIOCPARAM:
-		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_param))) {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_from_user(dbc_dev->payload, argp, sizeof(struct dbc_user_param)))
+			return -EFAULT;
 
 		*dbc_dev->payload_size = dbc_dev->header_size + sizeof(struct dbc_user_param);
 		ret = send_dbc_parameter(dbc_dev);
 		if (ret)
-			goto unlock;
+			return ret;
 
-		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_param)))  {
-			ret = -EFAULT;
-			goto unlock;
-		}
+		if (copy_to_user(argp, dbc_dev->payload, sizeof(struct dbc_user_param)))
+			return -EFAULT;
 		break;
 	default:
 		ret = -EINVAL;
 
 	}
-unlock:
-	mutex_unlock(&dbc_dev->ioctl_mutex);
 
 	return ret;
 }
-- 
2.43.0

Re: [PATCH] crypto: ccp: Use scoped guard for mutex

[Markus Elfring]

> Using a scoped guard simplifies the cleanup handling.

Will another imperative wording become helpful for an improved change description?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.12-rc6#n94

Regards,
Markus

Re: [PATCH] crypto: ccp: Use scoped guard for mutex

[Tom Lendacky]

On 11/8/24 20:00, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> Using a scoped guard simplifies the cleanup handling.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  drivers/crypto/ccp/dbc.c | 48 +++++++++++++++-------------------------
>  1 file changed, 18 insertions(+), 30 deletions(-)
> 

>  	default:
>  		ret = -EINVAL;

Might as well make this a return -EINVAL and get rid of the return ret
at the end of the function, too.

Thanks,
Tom

>  
>  	}
> -unlock:
> -	mutex_unlock(&dbc_dev->ioctl_mutex);
>  
>  	return ret;
>  }