ar7: replace mac address parsing

Replace sscanf() with mac_pton().

Quoted 1 line

Replace sscanf() with mac_pton().

[]

arch/mips/ar7/platform.c

Quoted 1 line

arch/mips/ar7/platform.c +0 -0

[]

arch/mips/ar7/platform.c static void __init cpmac_get_mac(int instance, unsigned char *dev_addr) · line 310

Quoted 9 lines

arch/mips/ar7/platform.c +1 -4

@@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
      }
 
      if (mac) {
-             if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
-                                     &dev_addr[0], &dev_addr[1],
-                                     &dev_addr[2], &dev_addr[3],
-                                     &dev_addr[4], &dev_addr[5]) != 6) {
+             if (!mac_pton(mac, dev_addr)) {

There is a slight functional change with this conversion.

mac_pton is strict about leading 0's and requires a 17 char strlen.

sscanf will accept 0:1:2:3:4:5, mac_pton will not.

arch/mips/ar7/platform.c static void __init cpmac_get_mac(int instance, unsigned char *dev_addr) · line 312

Quoted 2 lines

arch/mips/ar7/platform.c +0 -0

                      pr_warning("cannot parse mac address, "
                                      "using random address\n");

could be coalesced and pr_warn

                        pr_warn("cannot parse mac address - using random address\n");

2014-06-24 8:48 GMT-07:00 Joe Perches <[email protected]>:

Quoted 17 lines · Daniel Walter

Quoted 1 line

Replace sscanf() with mac_pton().

[]

arch/mips/ar7/platform.c

Quoted 1 line

arch/mips/ar7/platform.c +0 -0

[]

arch/mips/ar7/platform.c static void __init cpmac_get_mac(int instance, unsigned char *dev_addr) · line 310

Quoted 9 lines

arch/mips/ar7/platform.c +1 -4

@@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
      }
 
      if (mac) {
-             if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
-                                     &dev_addr[0], &dev_addr[1],
-                                     &dev_addr[2], &dev_addr[3],
-                                     &dev_addr[4], &dev_addr[5]) != 6) {
+             if (!mac_pton(mac, dev_addr)) {

There is a slight functional change with this conversion.

Quoted 1 line

mac_pton is strict about leading 0's and requires a 17 char strlen.

I do not have my devices handy, but I am fairly positive the use of sscanf() was exactly for that, we may or may not have leading zeroes. I am feeling a little uncomfortable with random code changes like that without being actually able to test on real hardware that has a variety of bootloaders and environment variables.

       for (i = 0; i < 6; i++)
               dev_addr[i] = (char2hex(mac[i * 3]) << 4) +
                       char2hex(mac[i * 3 + 1]);

So I'm tempted to say it should not cause any issues. But my sample size is rather small.

Quoted 18 lines · Florian Fainelli

2014-06-24 8:48 GMT-07:00 Joe Perches <[email protected]>:

Quoted 17 lines · Daniel Walter

Quoted 1 line

Replace sscanf() with mac_pton().

[]

arch/mips/ar7/platform.c

Quoted 1 line

arch/mips/ar7/platform.c +0 -0

[]

arch/mips/ar7/platform.c static void __init cpmac_get_mac(int instance, unsigned char *dev_addr) · line 310

Quoted 9 lines

arch/mips/ar7/platform.c +1 -4

@@ -307,10 +307,7 @@ static void __init cpmac_get_mac(int instance, unsigned char *dev_addr)
      }
 
      if (mac) {
-             if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
-                                     &dev_addr[0], &dev_addr[1],
-                                     &dev_addr[2], &dev_addr[3],
-                                     &dev_addr[4], &dev_addr[5]) != 6) {
+             if (!mac_pton(mac, dev_addr)) {

There is a slight functional change with this conversion.

Quoted 7 lines

Quoted 1 line

mac_pton is strict about leading 0's and requires a 17 char strlen.

I do not have my devices handy, but I am fairly positive the use of sscanf() was exactly for that, we may or may not have leading zeroes. I am feeling a little uncomfortable with random code changes like that without being actually able to test on real hardware that has a variety of bootloaders and environment variables.

One of my two devices has a mac address with one of the numbers being < 16, and it uses a fixed length mac:

(psbl) printenv
...
HWA_0 00:16:B6:2A:A4:3B

Also looking at the history[1] of this code, it looks like this was just an optimization of an earlier code which did expect 17 char len:

       for (i = 0; i < 6; i++)
               dev_addr[i] = (char2hex(mac[i * 3]) << 4) +
                       char2hex(mac[i * 3 + 1]);

So I'm tempted to say it should not cause any issues. But my sample size is rather small.
[1] d16f7093b6eb4f3859856f6ee4ab504cbeeea0b9