linux-kernel - Re: [PATCH v2] ath10k: skip the wait for completion to recovery in shutdown path

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Date:   Mon, 07 Dec 2020 18:12:38 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Youghandhar Chintala <youghand@...eaurora.org>,
        kuabhs@...omium.org,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        ath10k <ath10k@...ts.infradead.org>,
        Doug Anderson <dianders@...omium.org>,
        Rakesh Pillai <pillair@...eaurora.org>
Subject: Re: [PATCH v2] ath10k: skip the wait for completion to recovery in shutdown path

Brian Norris <briannorris@...omium.org> writes:

> On Thu, Nov 26, 2020 at 9:16 AM Youghandhar Chintala
> <youghand@...eaurora.org> wrote:
>> --- a/drivers/net/wireless/ath/ath10k/snoc.c
>> +++ b/drivers/net/wireless/ath/ath10k/snoc.c
>> @@ -1790,9 +1790,6 @@ static int ath10k_snoc_remove(struct platform_device *pdev)
>>
>>         reinit_completion(&ar->driver_recovery);
>>
>> -       if (test_bit(ATH10K_SNOC_FLAG_RECOVERY, &ar_snoc->flags))
>> -               wait_for_completion_timeout(&ar->driver_recovery, 3 * HZ);
>
> Hmm, this is the only instance of waiting for this completion, which
> means that after this patch, 'ar->driver_recovery' is doing exactly
> nothing. Should you instead just remove it completely?
>
> Also, if your patch is correct, it seems like the completion was never
> needed in the first place. You should probably address such a claim in
> the commit message; is there truly no need to wait here? Or was there
> some purpose here, but that purpose was accomplished some other way?
> Or was there a purpose, and that purpose was misguided? It feels to me
> like it is indeed correct to remove this (shutdown should be performed
> promptly; we don't need to delay it just to try to "finish
> recovering"), but it's your job to convince the reader.

Exactly what I was thinking as well. To me this patch was just looks
racy and all the commit log says that it's "unwanted delay".

-- 
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https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches