Re: [PATCH v1 2/2] net: rfkill: Fix a logic error within rfkill_set_hw_state_reason()

[quic_zijuhu <quic_zijuhu@quicinc.com>]

On 6/12/2024 4:18 PM, Johannes Berg wrote:
> On Fri, 2024-06-07 at 22:40 +0800, Zijun Hu wrote:
>> Kernel API rfkill_set_hw_state_reason() wrongly gets previous block state
>> by using its parameter @reason as reason mask.
> 
> Using reason as a mask is perfectly valid.
> 
> And checking that the bit changed also seems valid.
> 
i don't think so as explained below.
let us assume @rfkill->hard_block_reasons has value
RFKILL_HARD_BLOCK_SIGNAL which means block state before
__rfkill_set_sw_state(..., true, RFKILL_HARD_BLOCK_NOT_OWNER) is invoked.

@prev should mean previous block state, @prev will have false based on
current logic, it is wrong since rfkill have block state before the call.

> We might want to not schedule the worker if it's not needed, but that's
> a different issue, I don't see a real bug here?
> 
the worker will be unneccessarily scheduled for above example based on
current logic even if the rfkill always stay in block state.
> johannes
>