Re: [PATCH] libata: fallback to the other IDENTIFY on device error,take#2

[Tejun Heo]

Dave Jones wrote:
> On Sun, May 13, 2007 at 02:57:44PM +0200, Tejun Heo wrote:
>  > Jeff Garzik wrote:
>  > > Tejun Heo wrote:
>  > >> +            if (class == ATA_DEV_ATA)
>  > >> +                class = ATA_DEV_ATAPI;
>  > >> +            else
>  > >> +                class = ATA_DEV_ATA;
>  > > 
>  > > 
>  > > the 'else' branch is obviously redundant
>  > 
>  > Why?  We can also fallback from ATAPI to ATA.
> 
> Then did you mean to write..
> 
> +            if (class == ATA_DEV_ATA)
> +                class = ATA_DEV_ATAPI;
> +            else if (class == ATA_DEV_ATAPI)
> +                class = ATA_DEV_ATA;
> 
> ?
> 
> Otherwise, as Jeff mentions, you're doing a redundant assignment
> in the else branch.

Hmmm... I'm feeling very dense today.  At that point, class is either
ATA_DEV_ATA or ATA_DEV_ATAPI.  The if-else clause tries to flip between
the two.

1. if class == ATA_DEV_ATA, the 'if' test succeeds and "class =
ATA_DEV_ATAPI" runs, so it flips correctly.

2. if class == ATA_DEV_ATAPI,  the 'if' test fails and "class =
ATA_DEV_ATA" runs, so it flips correctly.

What am I missing here?  Feel free to scream at me and hammer me into
senses.  :-)

-- 
tejun
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