Received-SPF: pass (google.com: domain of linux-wireless+bounces-8846-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45e3:2400::1 as permitted sender) client-ip=2604:1380:45e3:2400::1;
Message-ID: <b8610296-f8cf-4b61-9b64-ffb52b7ab251@quicinc.com>
Date: Wed, 12 Jun 2024 17:43:33 +0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v1 2/2] net: rfkill: Fix a logic error within
 rfkill_set_hw_state_reason()
To: Johannes Berg <johannes@sipsolutions.net>, <davem@davemloft.net>,
        <edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>,
        <emmanuel.grumbach@intel.com>
CC: <linux-wireless@vger.kernel.org>, <netdev@vger.kernel.org>
References: <1717771212-30723-1-git-send-email-quic_zijuhu@quicinc.com>
 <1717771212-30723-3-git-send-email-quic_zijuhu@quicinc.com>
 <b3e0a55f0680b590537133bfb02cd1bbfd61a56e.camel@sipsolutions.net>
Content-Language: en-US
From: quic_zijuhu <quic_zijuhu@quicinc.com>
In-Reply-To: <b3e0a55f0680b590537133bfb02cd1bbfd61a56e.camel@sipsolutions.net>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit

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
>