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Message-ID: <be3576e234177f8da28be8ba37fd369c00fb548d.camel@sipsolutions.net>
Subject: Re: [PATCH v1 2/2] net: rfkill: Fix a logic error within
 rfkill_set_hw_state_reason()
From: Johannes Berg <johannes@sipsolutions.net>
To: quic_zijuhu <quic_zijuhu@quicinc.com>, 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
Date: Wed, 12 Jun 2024 12:11:26 +0200
In-Reply-To: <b8610296-f8cf-4b61-9b64-ffb52b7ab251@quicinc.com>
References: <1717771212-30723-1-git-send-email-quic_zijuhu@quicinc.com>
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	 <b3e0a55f0680b590537133bfb02cd1bbfd61a56e.camel@sipsolutions.net>
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On Wed, 2024-06-12 at 17:43 +0800, quic_zijuhu wrote:
> 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 s=
tate
> > > by using its parameter @reason as reason mask.
> >=20
> > Using reason as a mask is perfectly valid.
> >=20
> > And checking that the bit changed also seems valid.
> >=20
> 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.
>=20
> @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.
>=20
> > 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?
> >=20
> the worker will be unneccessarily scheduled for above example based on
> current logic even if the rfkill always stay in block state.
> >=20

But yes, this is right. It's just not a bug.

johannes