linux-kernel - Re: [PATCH v2] scsi: pm8001: Fix data race in sysfs SAS address read

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Message-ID: <CAAo+4rWk2ZgjSVk9bMSh683drt-bW9EjkYgBsS4q8CcraGDEBQ@mail.gmail.com>
Date: Fri, 16 Jan 2026 21:41:55 +0800
From: Chengfeng Ye <dg573847474@...il.com>
To: James Bottomley <James.Bottomley@...senpartnership.com>
Cc: Jinpu Wang <jinpu.wang@...os.com>, 
	"Martin K . Petersen" <martin.petersen@...cle.com>, Bart Van Assche <bvanassche@....org>, 
	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Chengfeng Ye <cyeaa@...nect.ust.hk>
Subject: Re: [PATCH v2] scsi: pm8001: Fix data race in sysfs SAS address read

Hi James,

> I think everyone would agree this can't happen for built in drivers
> (because user space doesn't start until long after driver init), so
> your theory above rests on a race between inserting the module and a
> tool reading the file which can be fixed by waiting a short period ...
> it just doesn't seem to be an important issue.

True for the case of built-in driver (most use scenario), the race
window is short.

> Whereas taking the internal host lock in a
> sysfs read routine could potentially be a DoS vector.

Agree that using a spinlock just to fix this hardly triggered output
issue may not be a good idea.
I think this theoretical uninitialized/torn-read issue could also be
fixed by delaying the creation of the sysfs folder until
initialization finishes. Can help create a new patch if you'd like to
improve the code, or we can just ignore it if it is not worth
bothering with a small issue like this.

Best regards,
Chengfeng