linux-kernel - Re: [net v1] net: wwan: t7xx: Fix napi rx poll issue

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Message-ID: <20250516084842.26c80cb5@kernel.org>
Date: Fri, 16 May 2025 08:48:42 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Jinjian Song <jinjian.song@...ocom.com>
Cc: andrew+netdev@...n.ch, angelogioacchino.delregno@...labora.com,
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Subject: Re: [net v1] net: wwan: t7xx: Fix napi rx poll issue

On Fri, 16 May 2025 15:30:38 +0800 Jinjian Song wrote:
> It seems that a judgment is made every time ccmni_inst[x] is used in the driver,
> and the synchronization on the 2 way might have been done when NAPI triggers
> polling by napi_schedule and when WWAN trigger dellink. 

Synchronization is about ensuring that the condition validating
by the if() remains true for as long as necessary.
You need to wrap the read with READ_ONCE() and write with WRITE_ONCE().
The rest if fine because netdev unregister sync against NAPIs in flight.