netdev - Re: [PATCH net v2] devlink: Fix devlink parallel commands processing

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Date: Tue, 12 Mar 2024 13:13:21 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Shay Drory <shayd@...dia.com>
Cc: netdev@...r.kernel.org, pabeni@...hat.com, davem@...emloft.net,
	kuba@...nel.org, edumazet@...gle.com, jiri@...dia.com
Subject: Re: [PATCH net v2] devlink: Fix devlink parallel commands processing

Tue, Mar 12, 2024 at 11:52:38AM CET, shayd@...dia.com wrote:
>Commit 870c7ad4a52b ("devlink: protect devlink->dev by the instance
>lock") added devlink instance locking inside a loop that iterates over
>all the registered devlink instances on the machine in the pre-doit
>phase. This can lead to serialization of devlink commands over
>different devlink instances.
>
>For example: While the first devlink instance is executing firmware
>flash, all commands to other devlink instances on the machine are
>forced to wait until the first devlink finishes.
>
>Therefore, in the pre-doit phase, take the devlink instance lock only
>for the devlink instance the command is targeting. Devlink layer is
>taking a reference on the devlink instance, ensuring the devlink->dev
>pointer is valid. This reference taking was introduced by commit
>a380687200e0 ("devlink: take device reference for devlink object").
>Without this commit, it would not be safe to access devlink->dev
>lockless.
>
>Fixes: 870c7ad4a52b ("devlink: protect devlink->dev by the instance lock")
>Signed-off-by: Shay Drory <shayd@...dia.com>
>---
>v1->v2:
> - Simplify the code by removing the goto

Indeed nicer. Thanks!

Reviewed-by: Jiri Pirko <jiri@...dia.com>