can: isotp: implement cleanups / improvements from review

As pointed out by Jakub Kicinski here:
http://lore.kernel.org/r/20201009175751.5c54097f@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com
this patch addresses the remarked issues:

- remove empty line in comment
- remove default=y for CAN_ISOTP in Kconfig
- make use of pr_notice_once()
- use GFP_ATOMIC instead of gfp_any() in soft hrtimer context

The version strings in the CAN subsystem are removed by a separate patch.
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/r/20201012074354.25839-1-socketcan@hartkopp.netSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

include/uapi/linux/can/isotp.h

@@ -160,7 +160,6 @@ struct can_isotp_ll_options {
  * these default settings can be changed via sockopts.
  * For that reason the STmin value is intentionally _not_ checked for
  * consistency and copied directly into the flow control (FC) frame.
- *
  */
 
 #endif /* !_UAPI_CAN_ISOTP_H */

net/can/Kconfig

@@ -57,7 +57,6 @@ source "net/can/j1939/Kconfig"
 
 config CAN_ISOTP
 	tristate "ISO 15765-2:2016 CAN transport protocol"
-	default y
 	help
 	  CAN Transport Protocols offer support for segmented Point-to-Point
 	  communication between CAN nodes via two defined CAN Identifiers.
@@ -67,6 +66,8 @@ config CAN_ISOTP
 	  vehicle diagnosis (UDS, ISO 14229) or IP-over-CAN traffic.
 	  This protocol driver implements data transfers according to
 	  ISO 15765-2:2016 for 'classic' CAN and CAN FD frame types.
+	  If you want to perform automotive vehicle diagnostic services (UDS),
+	  say 'y'.
 
 source "drivers/net/can/Kconfig"
 

net/can/isotp.c

@@ -222,8 +222,8 @@ static int isotp_send_fc(struct sock *sk, int ae, u8 flowstatus)
 
 	can_send_ret = can_send(nskb, 1);
 	if (can_send_ret)
-		printk_once(KERN_NOTICE "can-isotp: %s: can_send_ret %d\n",
-			    __func__, can_send_ret);
+		pr_notice_once("can-isotp: %s: can_send_ret %d\n",
+			       __func__, can_send_ret);
 
 	dev_put(dev);
 
@@ -769,7 +769,7 @@ static enum hrtimer_restart isotp_tx_timer_handler(struct hrtimer *hrtimer)
 
 isotp_tx_burst:
 		skb = alloc_skb(so->ll.mtu + sizeof(struct can_skb_priv),
-				gfp_any());
+				GFP_ATOMIC);
 		if (!skb) {
 			dev_put(dev);
 			break;
@@ -798,8 +798,8 @@ static enum hrtimer_restart isotp_tx_timer_handler(struct hrtimer *hrtimer)
 
 		can_send_ret = can_send(skb, 1);
 		if (can_send_ret)
-			printk_once(KERN_NOTICE "can-isotp: %s: can_send_ret %d\n",
-				    __func__, can_send_ret);
+			pr_notice_once("can-isotp: %s: can_send_ret %d\n",
+				       __func__, can_send_ret);
 
 		if (so->tx.idx >= so->tx.len) {
 			/* we are done */
@@ -942,8 +942,8 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	err = can_send(skb, 1);
 	dev_put(dev);
 	if (err) {
-		printk_once(KERN_NOTICE "can-isotp: %s: can_send_ret %d\n",
-			    __func__, err);
+		pr_notice_once("can-isotp: %s: can_send_ret %d\n",
+			       __func__, err);
 		return err;
 	}