[Intel-wired-lan] [PATCH] igc: Do not use link uninitialized in igc_check_for_copper_link
Neftin, Sasha
sasha.neftin at intel.com
Sun Jul 19 05:34:12 UTC 2020
On 7/17/2020 05:12, Nathan Chancellor wrote:
> On Thu, Jul 16, 2020 at 07:29:03PM +0300, Neftin, Sasha wrote:
>> On 7/16/2020 07:49, Nathan Chancellor wrote:
>>> Clang warns:
>>>
>> Hello Nathan,
>> Thanks for tracking our code.Please, look at https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20200709073416.14126-1-sasha.neftin@intel.com/
>> - I hope this patch already address this Clang warns - please, let me know.
>
> I have not explicitly tested it but it seems obvious that it will. Let's
> go with that.
>
Good Nathan, let's go with my
https://patchwork.ozlabs.org/project/intel-wired-lan/patch/20200709073416.14126-1-sasha.neftin@intel.com/
and let me know if warning still generated.
Thanks,
Sasha
> Cheers,
> Nathan
>
>>> drivers/net/ethernet/intel/igc/igc_mac.c:374:6: warning: variable 'link'
>>> is used uninitialized whenever 'if' condition is true
>>> [-Wsometimes-uninitialized]
>>> if (!mac->get_link_status) {
>>> ^~~~~~~~~~~~~~~~~~~~~
>>> drivers/net/ethernet/intel/igc/igc_mac.c:424:33: note: uninitialized use
>>> occurs here
>>> ret_val = igc_set_ltr_i225(hw, link);
>>> ^~~~
>>> drivers/net/ethernet/intel/igc/igc_mac.c:374:2: note: remove the 'if' if
>>> its condition is always false
>>> if (!mac->get_link_status) {
>>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> drivers/net/ethernet/intel/igc/igc_mac.c:367:11: note: initialize the
>>> variable 'link' to silence this warning
>>> bool link;
>>> ^
>>> = 0
>>> 1 warning generated.
>>>
>>> It is not wrong, link is only uninitialized after this through
>>> igc_phy_has_link. Presumably, if we skip the majority of this function
>>> when get_link_status is false, we should skip calling igc_set_ltr_i225
>>> as well. Just directly return 0 in this case, rather than bothering with
>>> adding another label or initializing link in the if statement.
>>>
>>> Fixes: 707abf069548 ("igc: Add initial LTR support")
>>> Link: https://github.com/ClangBuiltLinux/linux/issues/1095
>>> Signed-off-by: Nathan Chancellor <natechancellor at gmail.com>
>>> ---
>>> drivers/net/ethernet/intel/igc/igc_mac.c | 6 ++----
>>> 1 file changed, 2 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/intel/igc/igc_mac.c b/drivers/net/ethernet/intel/igc/igc_mac.c
>>> index b47e7b0a6398..26e3c56a4a8b 100644
>>> --- a/drivers/net/ethernet/intel/igc/igc_mac.c
>>> +++ b/drivers/net/ethernet/intel/igc/igc_mac.c
>>> @@ -371,10 +371,8 @@ s32 igc_check_for_copper_link(struct igc_hw *hw)
>>> * get_link_status flag is set upon receiving a Link Status
>>> * Change or Rx Sequence Error interrupt.
>>> */
>>> - if (!mac->get_link_status) {
>>> - ret_val = 0;
>>> - goto out;
>>> - }
>>> + if (!mac->get_link_status)
>>> + return 0;
>>> /* First we want to see if the MII Status Register reports
>>> * link. If so, then we want to get the current speed/duplex
>>>
>>> base-commit: ca0e494af5edb59002665bf12871e94b4163a257
>>>
>> Thanks,
>> Sasha
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