linux-kernel - Re: [PATCH 02/22] greybus: Use alloc_ordered_workqueue() to create ordered workqueues

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Message-ID: <ZEItNlmuw5MHDBXH@hovoldconsulting.com>
Date:   Fri, 21 Apr 2023 08:29:10 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     jiangshanlai@...il.com, linux-kernel@...r.kernel.org,
        kernel-team@...a.com, Alex Elder <elder@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        greybus-dev@...ts.linaro.org
Subject: Re: [PATCH 02/22] greybus: Use alloc_ordered_workqueue() to create
 ordered workqueues

On Thu, Apr 20, 2023 at 04:50:26PM -1000, Tejun Heo wrote:
> BACKGROUND
> ==========
> 
> When multiple work items are queued to a workqueue, their execution order
> doesn't match the queueing order. They may get executed in any order and
> simultaneously. When fully serialized execution - one by one in the queueing
> order - is needed, an ordered workqueue should be used which can be created
> with alloc_ordered_workqueue().

> This patch series audits all callsites that create an UNBOUND workqueue w/
> @max_active==1 and converts them to alloc_ordered_workqueue() as necessary.
> 
> WHAT TO LOOK FOR
> ================
> 
> The conversions are from
> 
>   alloc_workqueue(WQ_UNBOUND | flags, 1, args..)
> 
> to
> 
>   alloc_ordered_workqueue(flags, args...)
> 
> which don't cause any functional changes. If you know that fully ordered
> execution is not ncessary, please let me know. I'll drop the conversion and
> instead add a comment noting the fact to reduce confusion while conversion
> is in progress.
> 
> If you aren't fully sure, it's completely fine to let the conversion
> through. The behavior will stay exactly the same and we can always
> reconsider later.
> 
> As there are follow-up workqueue core changes, I'd really appreciate if the
> patch can be routed through the workqueue tree w/ your acks. Thanks.
> 
> Signed-off-by: Tejun Heo <tj@...nel.org>
> Cc: Johan Hovold <johan@...nel.org>
> Cc: Alex Elder <elder@...nel.org>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: greybus-dev@...ts.linaro.org

Acked-by: Johan Hovold <johan@...nel.org>