[PATCH 0/5] hamradio: mkiss: modernize and clean up mkiss driver

[PATCH 0/5] hamradio: mkiss: modernize and clean up mkiss driver

[Mashiro Chen]

This patch series modernizes the mkiss driver, which is used for
AX.25 communication over serial lines.

The series starts by moving variable assignments out of 'if'
conditions to improve code safety and readability.
The second patch removes redundant static initializations to 0.
The third patch fixes missing spaces around assignment operations.
The fourth patch modernizes the logging system by replacing legacy
printk() calls with netdev_* and pr_* macros for better
device-specific context.
The fifth patch addresses remaining checkpatch.pl issues, primarily
converting space-based indentation to tabs, aligning parameters, and
fixing comment formats.

These changes have been compile-tested.

Mashiro Chen (5):
  hamradio: mkiss: move assignments out of if conditions
  hamradio: mkiss: remove redundant static initialization to 0
  hamradio: mkiss: fix spacing around assignment operator
  hamradio: mkiss: modernize logging with netdev and pr macros
  hamradio: mkiss: cleanup indentation and coding style

 drivers/net/hamradio/mkiss.c | 98 ++++++++++++++++--------------------
 1 file changed, 44 insertions(+), 54 deletions(-)

-- 
2.53.0

[PATCH 1/5] hamradio: mkiss: move assignments out of if conditions

[Mashiro Chen]

Move assignments out of if conditions to comply with
the Linux Kernel coding style and improve code
readability. This also switches to the preferred
'if (!ptr)' idiom for NULL pointer checks.

Signed-off-by: Mashiro Chen <mashiro.chen@mailbox.org>
---
 drivers/net/hamradio/mkiss.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 5f38a002b..eac45d936 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -282,7 +282,8 @@ static void ax_bump(struct mkiss *ax)
 
 	count = ax->rcount;
 
-	if ((skb = dev_alloc_skb(count)) == NULL) {
+	skb = dev_alloc_skb(count);
+	if (!skb) {
 		printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n",
 		       ax->dev->name);
 		ax->dev->stats.rx_dropped++;
@@ -591,10 +592,12 @@ static int ax_open(struct net_device *dev)
 	if (len < 576 * 2)
 		len = 576 * 2;
 
-	if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
+	ax->rbuff = kmalloc(len + 4, GFP_KERNEL);
+	if (!ax->rbuff)
 		goto norbuff;
 
-	if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
+	ax->xbuff = kmalloc(len + 4, GFP_KERNEL);
+	if (!ax->xbuff)
 		goto noxbuff;
 
 	ax->mtu	     = dev->mtu + 73;
-- 
2.53.0

[PATCH 2/5] hamradio: mkiss: remove redundant static initialization to 0

[Mashiro Chen]

Static variables are automatically initialized to 0 by the
compiler.
Remove the explicit initialization to comply with the Linux
Kernel coding standards.

Signed-off-by: Mashiro Chen <mashiro.chen@mailbox.org>
---
 drivers/net/hamradio/mkiss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index eac45d936..3721572ce 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -686,7 +686,7 @@ static void mkiss_put(struct mkiss *ax)
 		complete(&ax->dead);
 }
 
-static int crc_force = 0;	/* Can be overridden with insmod */
+static int crc_force;	/* Can be overridden with insmod */
 
 static int mkiss_open(struct tty_struct *tty)
 {
-- 
2.53.0

[PATCH 3/5] hamradio: mkiss: fix spacing around assignment operator

[Mashiro Chen]

Add missing spaces around the assignment operator to
adhere to the Linux Kernel coding style.

Signed-off-by: Mashiro Chen <mashiro.chen@mailbox.org>
---
 drivers/net/hamradio/mkiss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 3721572ce..b9160b95f 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -201,7 +201,7 @@ static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc,
 	int len)
 {
 	unsigned char *ptr = d;
-	unsigned char c=0;
+	unsigned char c = 0;
 
 	*ptr++ = END;
 	while (len > 0) {
-- 
2.53.0

[PATCH 4/5] hamradio: mkiss: modernize logging with netdev and pr macros

[Mashiro Chen]

Replace legacy printk() calls with modern logging macros.
This allows for better device-specific context by using
netdev_err() and netdev_info() where possible. For global
module-level messages, use pr_info() and pr_err(). This
modernization also allows the removal of the redundant
'banner' and 'msg_regfail' static strings, simplifying
the driver initialization logic.

Signed-off-by: Mashiro Chen <mashiro.chen@mailbox.org>
---
 drivers/net/hamradio/mkiss.c | 51 ++++++++++++------------------------
 1 file changed, 17 insertions(+), 34 deletions(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index b9160b95f..75b9bd2e1 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -249,9 +249,7 @@ static void ax_bump(struct mkiss *ax)
 				return;
 			}
 			if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) {
-				printk(KERN_INFO
-				       "mkiss: %s: Switching to crc-smack\n",
-				       ax->dev->name);
+				netdev_info(ax->dev, "Switching to crc-smack\n");
 				ax->crcmode = CRC_MODE_SMACK;
 			}
 			ax->rcount -= 2;
@@ -263,9 +261,7 @@ static void ax_bump(struct mkiss *ax)
 				return;
 			}
 			if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) {
-				printk(KERN_INFO
-				       "mkiss: %s: Switching to crc-flexnet\n",
-				       ax->dev->name);
+				netdev_info(ax->dev, "Switching to crc-flexnet\n");
 				ax->crcmode = CRC_MODE_FLEX;
 			}
 			ax->rcount -= 2;
@@ -284,8 +280,7 @@ static void ax_bump(struct mkiss *ax)
 
 	skb = dev_alloc_skb(count);
 	if (!skb) {
-		printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n",
-		       ax->dev->name);
+		netdev_err(ax->dev, "memory squeeze, dropping packet.\n");
 		ax->dev->stats.rx_dropped++;
 		spin_unlock_bh(&ax->buflock);
 		return;
@@ -376,9 +371,7 @@ static void ax_changedmtu(struct mkiss *ax)
 	rbuff = kmalloc(len + 4, GFP_ATOMIC);
 
 	if (xbuff == NULL || rbuff == NULL)  {
-		printk(KERN_ERR "mkiss: %s: unable to grow ax25 buffers, "
-		       "MTU change cancelled.\n",
-		       ax->dev->name);
+		netdev_err(ax->dev, "unable to grow ax25 buffers, MTU change cancelled.\n");
 		dev->mtu = ax->mtu;
 		kfree(xbuff);
 		kfree(rbuff);
@@ -433,7 +426,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 		ax_changedmtu(ax);
 
 	if (len > ax->mtu) {		/* Sigh, shouldn't occur BUT ... */
-		printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name);
+		netdev_err(ax->dev, "truncating oversized transmit packet!\n");
 		dev->stats.tx_dropped++;
 		netif_start_queue(dev);
 		return;
@@ -469,8 +462,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 				  cmd = 0;
 				}
 				ax->crcauto = (cmd ? 0 : 1);
-				printk(KERN_INFO "mkiss: %s: crc mode set to %d\n",
-				       ax->dev->name, cmd);
+				netdev_info(ax->dev, "crc mode set to %d\n", cmd);
 			}
 			spin_unlock_bh(&ax->buflock);
 			netif_start_queue(dev);
@@ -484,7 +476,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 		switch (ax->crcmode) {
 		case CRC_MODE_SMACK_TEST:
 			ax->crcmode  = CRC_MODE_FLEX_TEST;
-			printk(KERN_INFO "mkiss: %s: Trying crc-smack\n", ax->dev->name);
+			netdev_info(ax->dev, "Trying crc-smack\n");
 			fallthrough;
 		case CRC_MODE_SMACK:
 			*p |= 0x80;
@@ -493,7 +485,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 			break;
 		case CRC_MODE_FLEX_TEST:
 			ax->crcmode = CRC_MODE_NONE;
-			printk(KERN_INFO "mkiss: %s: Trying crc-flexnet\n", ax->dev->name);
+			netdev_info(ax->dev, "Trying crc-flexnet\n");
 			fallthrough;
 		case CRC_MODE_FLEX:
 			*p |= 0x20;
@@ -526,7 +518,7 @@ static netdev_tx_t ax_xmit(struct sk_buff *skb, struct net_device *dev)
 		return ax25_ip_xmit(skb);
 
 	if (!netif_running(dev))  {
-		printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
+		netdev_err(ax->dev, "xmit call when iface is down\n");
 		return NETDEV_TX_BUSY;
 	}
 
@@ -540,8 +532,8 @@ static netdev_tx_t ax_xmit(struct sk_buff *skb, struct net_device *dev)
 			return NETDEV_TX_BUSY;
 		}
 
-		printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
-		       (tty_chars_in_buffer(ax->tty) || ax->xleft) ?
+		netdev_err(ax->dev, "transmit timed out, %s?\n",
+			   (tty_chars_in_buffer(ax->tty) || ax->xleft) ?
 		       "bad line quality" : "driver error");
 
 		ax->xleft = 0;
@@ -735,24 +727,20 @@ static int mkiss_open(struct tty_struct *tty)
 	switch (crc_force) {
 	case 3:
 		ax->crcmode  = CRC_MODE_SMACK;
-		printk(KERN_INFO "mkiss: %s: crc mode smack forced.\n",
-		       ax->dev->name);
+		netdev_info(ax->dev, "crc mode smack forced.\n");
 		break;
 	case 2:
 		ax->crcmode  = CRC_MODE_FLEX;
-		printk(KERN_INFO "mkiss: %s: crc mode flexnet forced.\n",
-		       ax->dev->name);
+		netdev_info(ax->dev, "crc mode flexnet forced.\n");
 		break;
 	case 1:
 		ax->crcmode  = CRC_MODE_NONE;
-		printk(KERN_INFO "mkiss: %s: crc mode disabled.\n",
-		       ax->dev->name);
+		netdev_info(ax->dev, "crc mode disabled.\n");
 		break;
 	case 0:
 	default:
 		crc_force = 0;
-		printk(KERN_INFO "mkiss: %s: crc mode is auto.\n",
-		       ax->dev->name);
+		netdev_info(ax->dev, "crc mode is auto.\n");
 		ax->crcmode  = CRC_MODE_SMACK_TEST;
 	}
 	ax->crcauto = (crc_force ? 0 : 1);
@@ -949,20 +937,15 @@ static struct tty_ldisc_ops ax_ldisc = {
 	.write_wakeup	= mkiss_write_wakeup
 };
 
-static const char banner[] __initconst = KERN_INFO \
-	"mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n";
-static const char msg_regfail[] __initconst = KERN_ERR \
-	"mkiss: can't register line discipline (err = %d)\n";
-
 static int __init mkiss_init_driver(void)
 {
 	int status;
 
-	printk(banner);
+	pr_info("mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n");
 
 	status = tty_register_ldisc(&ax_ldisc);
 	if (status != 0)
-		printk(msg_regfail, status);
+		pr_err("mkiss: can't register line discipline (err = %d)\n", status);
 
 	return status;
 }
-- 
2.53.0

[PATCH 5/5] hamradio: mkiss: cleanup indentation and coding style

[Mashiro Chen]

Clean up the remaining coding style issues in mkiss.c
to follow the Linux Kernel coding standards. The
primary changes include fixing indentation and
alignment issues by using tabs instead of spaces where
possible. Additionally, add missing spaces after
keywords and blank lines after variable declarations.
Block comment formatting is also adjusted to use a
separate line for the trailing delimiter.

Signed-off-by: Mashiro Chen <mashiro.chen@mailbox.org>
---
 drivers/net/hamradio/mkiss.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 75b9bd2e1..8939582ac 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -64,7 +64,7 @@ struct mkiss {
 #define AXF_OUTWAIT	4		/* is outpacket was flag	*/
 
 	int		mode;
-        int		crcmode;	/* MW: for FlexNet, SMACK etc.  */
+	int		crcmode;	/* MW: for FlexNet, SMACK etc.  */
 	int		crcauto;	/* CRC auto mode */
 
 #define CRC_MODE_NONE		0
@@ -439,27 +439,30 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 		/* Configuration Command (kissparms(1).
 		 * Protocol spec says: never append CRC.
 		 * This fixes a very old bug in the linux
-		 * kiss driver. -- dl9sau */
+		 * kiss driver. -- dl9sau
+		 */
 		switch (*p & 0xff) {
 		case 0x85:
 			/* command from userspace especially for us,
-			 * not for delivery to the tnc */
+			 * not for delivery to the tnc
+			 */
 			if (len > 1) {
 				int cmd = (p[1] & 0xff);
-				switch(cmd) {
+
+				switch (cmd) {
 				case 3:
-				  ax->crcmode = CRC_MODE_SMACK;
-				  break;
+					ax->crcmode = CRC_MODE_SMACK;
+					break;
 				case 2:
-				  ax->crcmode = CRC_MODE_FLEX;
-				  break;
+					ax->crcmode = CRC_MODE_FLEX;
+					break;
 				case 1:
-				  ax->crcmode = CRC_MODE_NONE;
-				  break;
+					ax->crcmode = CRC_MODE_NONE;
+					break;
 				case 0:
 				default:
-				  ax->crcmode = CRC_MODE_SMACK_TEST;
-				  cmd = 0;
+					ax->crcmode = CRC_MODE_SMACK_TEST;
+					cmd = 0;
 				}
 				ax->crcauto = (cmd ? 0 : 1);
 				netdev_info(ax->dev, "crc mode set to %d\n", cmd);
@@ -473,6 +476,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 		}
 	} else {
 		unsigned short crc;
+
 		switch (ax->crcmode) {
 		case CRC_MODE_SMACK_TEST:
 			ax->crcmode  = CRC_MODE_FLEX_TEST;
@@ -812,7 +816,7 @@ static int mkiss_ioctl(struct tty_struct *tty, unsigned int cmd,
 	switch (cmd) {
 	case SIOCGIFNAME:
 		err = copy_to_user((void __user *) arg, ax->dev->name,
-		                   strlen(ax->dev->name) + 1) ? -EFAULT : 0;
+				   strlen(ax->dev->name) + 1) ? -EFAULT : 0;
 		break;
 
 	case SIOCGIFENCAP:
@@ -828,7 +832,7 @@ static int mkiss_ioctl(struct tty_struct *tty, unsigned int cmd,
 		ax->mode = tmp;
 		dev->addr_len        = AX25_ADDR_LEN;
 		dev->hard_header_len = AX25_KISS_HEADER_LEN +
-		                       AX25_MAX_HEADER_LEN + 3;
+				       AX25_MAX_HEADER_LEN + 3;
 		dev->type            = ARPHRD_AX25;
 
 		err = 0;
@@ -838,7 +842,7 @@ static int mkiss_ioctl(struct tty_struct *tty, unsigned int cmd,
 		char addr[AX25_ADDR_LEN];
 
 		if (copy_from_user(&addr,
-		                   (void __user *) arg, AX25_ADDR_LEN)) {
+				   (void __user *)arg, AX25_ADDR_LEN)) {
 			err = -EFAULT;
 			break;
 		}
-- 
2.53.0

Re: [PATCH 0/5] hamradio: mkiss: modernize and clean up mkiss driver

[Jakub Kicinski]

On Sun, 29 Mar 2026 22:34:03 +0800 Mashiro Chen wrote:
> This patch series modernizes the mkiss driver, which is used for
> AX.25 communication over serial lines.

Quoting documentation:

  Clean-up patches
  ~~~~~~~~~~~~~~~~
  
  Netdev discourages patches which perform simple clean-ups, which are not in
  the context of other work. For example:
  
  * Addressing ``checkpatch.pl``, and other trivial coding style warnings
  * Addressing :ref:`Local variable ordering<rcs>` issues
  * Conversions to device-managed APIs (``devm_`` helpers)
  
  This is because it is felt that the churn that such changes produce comes
  at a greater cost than the value of such clean-ups.
  
  Conversely, spelling and grammar fixes are not discouraged.
  
See: https://www.kernel.org/doc/html/next/process/maintainer-netdev.html#clean-up-patches
-- 
pw-bot: reject

Re: [PATCH 0/5] hamradio: mkiss: modernize and clean up mkiss driver

[Mashiro Chen]

Hi Jakub,

Thank you for the quick review and for pointing out the Netdev policy
regarding clean-up patches. I apologize for the noise; I was not fully
aware of the specific guidelines for the Netdev subsystem in this regard.

I will respect these guidelines and focus my further contributions on
functional improvements or bug fixes.

Regarding the current series, I understand them do not meet the Netdev
Standard for clean-up patches and I will drop these submissions.

Thank you again for your time and guidance.

Best Regards,
Mashiro Chen