linux-kernel - Re: [PATCH] scsi: ibmvscsi: Don't use rc uninitialized in ibmvscsi_do

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Message-ID: <20190603032344.GA26021@archlinux-epyc>
Date:   Sun, 2 Jun 2019 20:23:44 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Tyrel Datwyler <tyreld@...ux.ibm.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        clang-built-linux@...glegroups.com, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: [PATCH] scsi: ibmvscsi: Don't use rc uninitialized in
 ibmvscsi_do_work

Hi Michael,

On Sun, Jun 02, 2019 at 08:15:38PM +1000, Michael Ellerman wrote:
> Hi Nathan,
> 
> It's always preferable IMHO to keep any initialisation as localised as
> possible, so that the compiler can continue to warn about uninitialised
> usages elsewhere. In this case that would mean doing the rc = 0 in the
> switch, something like:

I am certainly okay with implementing this in a v2. I mulled over which
would be preferred, I suppose I guessed wrong :) Thank you for the
review and input.

> 
> diff --git a/drivers/scsi/ibmvscsi/ibmvscsi.c b/drivers/scsi/ibmvscsi/ibmvscsi.c
> index 727c31dc11a0..7ee5755cf636 100644
> --- a/drivers/scsi/ibmvscsi/ibmvscsi.c
> +++ b/drivers/scsi/ibmvscsi/ibmvscsi.c
> @@ -2123,9 +2123,6 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
>  
>         spin_lock_irqsave(hostdata->host->host_lock, flags);
>         switch (hostdata->action) {
> -       case IBMVSCSI_HOST_ACTION_NONE:
> -       case IBMVSCSI_HOST_ACTION_UNBLOCK:
> -               break;
>         case IBMVSCSI_HOST_ACTION_RESET:
>                 spin_unlock_irqrestore(hostdata->host->host_lock, flags);
>                 rc = ibmvscsi_reset_crq_queue(&hostdata->queue, hostdata);
> @@ -2142,7 +2139,10 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
>                 if (!rc)
>                         rc = ibmvscsi_send_crq(hostdata, 0xC001000000000000LL, 0);
>                 break;
> +       case IBMVSCSI_HOST_ACTION_NONE:
> +       case IBMVSCSI_HOST_ACTION_UNBLOCK:
>         default:
> +               rc = 0;
>                 break;
>         }
> 
> 
> But then that makes me wonder if that's actually correct?
> 
> If we get an action that we don't recognise should we just throw it away
> like that? (by doing hostdata->action = IBMVSCSI_HOST_ACTION_NONE). Tyrel?

However, because of this, I will hold off on v2 until Tyrel can give
some feedback.

Thanks,
Nathan