Re: [PATCH]nfc: replace improper check device_is_registered() in nfc_se_io()

[Jakub Kicinski <kuba@kernel.org>]

On Tue, 15 Apr 2025 10:54:36 +0800 Chen Yufeng wrote:
> > On 14/04/2025 16:11, Chen Yufeng wrote:  
> > > A patch similar to commit da5c0f119203 ("nfc: replace improper check device_is_registered() in netlink related functions")  
> 
> > Please wrap commit message according to Linux coding style / submission
> > process (neither too early nor over the limit):
> > https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/process/submitting-patches.rst#L597  
> 
> Thanks for your reply!
> I have reorganized commit message as follows.
> 
> A patch similar to commit da5c0f119203 ("nfc: replace improper check 
> device_is_registered() in netlink related functions").
> 
> The nfc_se_io() function in the NFC subsystem suffers from a race 
> condition similar to previously reported issues in other netlink-related 
> functions. The function checks device status using device_is_registered(),
> but this check can race with device unregistration despite being protected
> by device_lock.
> 
> This patch also uses bool variable dev->shutting_down instead of
> device_is_registered() to judge whether the nfc device is registered,
> which is well synchronized.

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