linux-kernel - Re: [PATCH] smp: smp_call_on_cpu(): use INIT_WORK_ONSTACK() for automatic work

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Message-ID: <20160923072117.GK2794@worktop>
Date:   Fri, 23 Sep 2016 09:21:17 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Nicolai Stange <nicstange@...il.com>
Cc:     Juergen Gross <jgross@...e.com>, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Davidlohr Bueso <dave@...olabs.net>,
        Richard Weinberger <richard@....at>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] smp: smp_call_on_cpu(): use INIT_WORK_ONSTACK() for
 automatic work_struct

On Thu, Sep 22, 2016 at 09:15:52PM +0200, Nicolai Stange wrote:

> One minor question regarding your patch though: it hasn't got a
> destroy_work_on_stack(). Isn't one needed because of
>   INIT_WORK_ONSTACK() -> __INIT_WORK() -> __init_work() ->
>   debug_object_init_on_stack() ?
> At least work_on_cpu() destroys its local work_struct that way...

I wasn't aware of destroy_work_on_stack(), and I'm not familiar enough
with the debug objects stuff to see hwo important it is to call.

Also, there's more INIT_WORK_ONSTACK usage lacking
destroy_work_on_stack() calls.

Maybe it would be good to do a patch fixing them all up and adding a
comment with INIT_WORK_ONSTACK() that says it ought to be paired with
destroy_work_on_stack().