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SubjectRe: [PATCH] Fix PCI error token awkward value
linas@austin.ibm.com (Linas Vepstas) wrote:
>
>
>
> The pci channel state token currently has a poor choice of values;
> there are two ways of indicating that "everything's OK": 0 and 1.
> This is a bit of a burden.
>
> If a devce driver wants to check if the pci channel is in a working
> or a disconnected state, the driver writer must perform checks similar
> to
>
> if((pdev->error_state != 0) &&
> (pdev->error_state != pci_channel_io_normal)) {
> whatever();
> }
>
> which is rather akward. The first check is needed because
> stuct pci_dev is inited to all-zeros. The scond is needed
> because the error recovery will set the state to
> pci_channel_io_normal (which is not zero).
>
> This patch fixes this awkwardness.
>

eww.

>
> Index: linux-2.6.17-mm3/include/linux/pci.h
> ===================================================================
> --- linux-2.6.17-mm3.orig/include/linux/pci.h 2006-06-27 11:39:16.000000000 -0500
> +++ linux-2.6.17-mm3/include/linux/pci.h 2006-07-06 15:15:09.000000000 -0500
> @@ -85,7 +85,7 @@ typedef unsigned int __bitwise pci_chann
>
> enum pci_channel_state {
> /* I/O channel is in normal state */
> - pci_channel_io_normal = (__force pci_channel_state_t) 1,
> + pci_channel_io_normal = (__force pci_channel_state_t) 0,
>
> /* I/O to channel is blocked */
> pci_channel_io_frozen = (__force pci_channel_state_t) 2,

It needs a comment to prevent people from breaking it in the future, and
to help people who are trying to work out why the heck the kernel is
looking for a particular state in something which hasn't been set to that
state.

Also, it's a bit odd that we've gone and left a hole in the enum space.


Wouldn't it be better to sort out our initialisation so we don't actually
need this memset-equals-pci_channel_io_normal trick? pci_scan_device()
looks like a good place..
-
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