Re: [PATCH linux-next] net: smc911x: replace ternary operator with min()

Hi Jakub,

On Wed, May 18, 2022 at 5:33 PM Jakub Kicinski [off-list ref] wrote:

On Wed, 18 May 2022 11:07:08 +0200 Geert Uytterhoeven wrote:

quoted

On Mon, May 16, 2022 at 10:36 PM Guo Zhengkui [off-list ref] wrote:

quoted

Fix the following coccicheck warning:

drivers/net/ethernet/smsc/smc911x.c:483:20-22: WARNING opportunity for min()

Signed-off-by: Guo Zhengkui <redacted>

Thanks for your patch, which is now commit 5ff0348b7f755aac ("net:
smc911x: replace ternary operator with min()") in net-next/master.

quoted

--- a/drivers/net/ethernet/smsc/smc911x.c
+++ b/drivers/net/ethernet/smsc/smc911x.c

@@ -480,7 +480,7 @@ static void smc911x_hardware_send_pkt(struct net_device *dev)
        SMC_SET_TX_FIFO(lp, cmdB);

        DBG(SMC_DEBUG_PKTS, dev, "Transmitted packet\n");
-       PRINT_PKT(buf, len <= 64 ? len : 64);
+       PRINT_PKT(buf, min(len, 64));

Unfortunately you forgot to test-compile this with
ENABLE_SMC_DEBUG_PKTS=1, which triggers:

        drivers/net/ethernet/smsc/smc911x.c: In function
‘smc911x_hardware_send_pkt’:
        include/linux/minmax.h:20:28: error: comparison of distinct
pointer types lacks a cast [-Werror]
           20 |  (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
              |                            ^~
        drivers/net/ethernet/smsc/smc911x.c:483:17: note: in expansion
of macro ‘min’
          483 |  PRINT_PKT(buf, min(len, 64));

"len" is "unsigned int", while "64" is "(signed) int".

Ah, damn. I did double check that the build test actually compiles
smc911x.o 'cause this patch looked suspicious. Didn't realize that
more than allmodconfig is needed to trigger this :/

How do you enable ENABLE_SMC_DEBUG_PKTS? You edit the source?

Yes you do.

To avoid missing stuff like this in the future, my fix also includes
a change to the dummy PRINT_PKT(), so you don't have to enable
ENABLE_SMC_DEBUG_PKTS anymore to trigger the issue.

quoted

I have sent a fix
https://lore.kernel.org/r/ca032d4122fc70d3a56a524e5944a8eff9a329e8.1652864652.git.geert+renesas@glider.be/ (local)

Thanks a lot!

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds