linux-kernel - Re: [PATCH 3/3] ipmi:bt-bmc: Fix error handling and status check

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Date:   Sat, 18 Apr 2020 15:23:54 +0800
From:   Tang Bin <tangbin@...s.chinamobile.com>
To:     minyard@....org
Cc:     arnd@...db.de, gregkh@...uxfoundation.org,
        openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] ipmi:bt-bmc: Fix error handling and status check

Hi Corey:

On 2020/4/18 10:14, Corey Minyard wrote:
> Sorry for the delay, I have had a lot of distractions.

No no no,  it's greatly appreciated  for your instruction. Thanks.

>
> The trouble is that the handling of bt_bmc->irq needs to be consistent.
> Either it needs to be negative if the irq allocation fails, or it needs
> to be zero if the irq allocation fails.  I think it needs to be negative
> because zero is a valid interrupt in some cases.
>
> Consider the following code:
>
>         bt_bmc_config_irq(bt_bmc, pdev);
>
>          if (bt_bmc->irq) {
>                  dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
>          } else {
>                  dev_info(dev, "No IRQ; using timer\n");
>                  timer_setup(&bt_bmc->poll_timer, poll_timer, 0);
>
> If bt_bmc->irq is negative (if platform_get_irq_optional() fails), it
> will say it's using the irq and won't start a timer and the driver won't
> work.  Then later (in your change below) it will try to stop the timer
> even though it's not running.
>
> If devm_request_irq() fails, then the interrupt is not set, but since
> bt_bmc->irq is most likely not zero, it will not start the timer and the
> driver won't work.
>
> You really need to set bt_bmc->irq negative if it fails.  And fix the
> check above to be if (bt_bmc->irq >= 0).

Got it. You are right, I am lacking in consideration here.


Thank you very much, I will send the v2.

Tang Bin

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