Re: [PATCH 1/2] mt76: mt7915: fix unused 'mode' variable

From: Nathan Chancellor
Date: Thu Feb 25 2021 - 13:05:15 EST


On Thu, Feb 25, 2021 at 03:59:14PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> clang points out a possible corner case in the mt7915_tm_set_tx_cont()
> function if called with invalid arguments:
>
> drivers/net/wireless/mediatek/mt76/mt7915/testmode.c:593:2: warning: variable 'mode' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
> default:
> ^~~~~~~
> drivers/net/wireless/mediatek/mt76/mt7915/testmode.c:597:13: note: uninitialized use occurs here
> rateval = mode << 6 | rate_idx;
> ^~~~
> drivers/net/wireless/mediatek/mt76/mt7915/testmode.c:506:37: note: initialize the variable 'mode' to silence this warning
> u8 rate_idx = td->tx_rate_idx, mode;
> ^
>
> Change it to return an error instead of continuing with invalid data
> here.
>
> Fixes: 3f0caa3cbf94 ("mt76: mt7915: add support for continuous tx in testmode")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/net/wireless/mediatek/mt76/mt7915/testmode.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/testmode.c b/drivers/net/wireless/mediatek/mt76/mt7915/testmode.c
> index 7fb2170a9561..aa629e1fb420 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/testmode.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/testmode.c
> @@ -543,6 +543,7 @@ mt7915_tm_set_tx_cont(struct mt7915_phy *phy, bool en)
> tx_cont->bw = CMD_CBW_20MHZ;
> break;
> default:
> + return -EINVAL;

Remove the break if we are adding a return?

> break;
> }
>
> @@ -591,6 +592,7 @@ mt7915_tm_set_tx_cont(struct mt7915_phy *phy, bool en)
> mode = MT_PHY_TYPE_HE_MU;
> break;
> default:
> + return -EINVAL;
> break;
> }
>
> --
> 2.29.2
>