Re: [PATCH] [v2] iwlwifi: pcie: fix constant-conversion warning

On Thu, Nov 11, 2021 at 8:31 AM Arnd Bergmann [off-list ref] wrote:

From: Arnd Bergmann <arnd@arndb.de>

clang points out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty:

drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
        for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
               ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~

This is still harmless, as the loop correctly terminates, but adding
an extra range check makes that obvious to both readers and to the
compiler.

Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
Reported-by: kernel test robot <redacted>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Something went wrong on my end: I thought this was a clang warning and
that I had
fixed it because it didn't come back with my v2 patch. However I now see it in
my gcc-11 test builds, so I assume this was a gcc warning all along, and that
my patch does nothing. Please disregard it if you have not already applied it.

       Arnd