Re: [PATCH 0/3] Revert MSI msg API churn

[Bjorn Helgaas]

On Wed, Oct 01, 2014 at 10:48:16AM -0600, Alex Williamson wrote:
> The MSI message API has gone through some churn, that I think results
> in an inconsistent interface.  We now have this:
> 
> void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void write_msi_msg(unsigned int irq, struct msi_msg *msg);
> 
> write_msi_msg() takes an irq arg, but read_msi_msg() takes an
> msi_desc.  Presumably write_msi_msg() was not converted because it
> has a much larger user base, but this sort of inconsitency results
> in a poor API.

Yeah, that isn't good, thanks for noticing.

I rebuilt the pci/msi branch and dropped the commits you mentioned.
The ones that are left are these:

  56b72b409579 PCI/MSI: Use __write_msi_msg() instead of write_msi_msg()
  1e8f4cc82ede MSI/powerpc: Use __read_msi_msg() instead of read_msi_msg()
  2b260085e466 PCI/MSI: Use __get_cached_msi_msg() instead of get_cached_msi_msg()

which I think are OK.

> This series reverts a selection of commits to return us to:
> 
> void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
> void write_msi_msg(unsigned int irq, struct msi_msg *msg);
> 
> I've left the removal of read_msi_msg() since it has no users, but
> restored get_cached_msi_msg() since it has an imminent user.  This
> will also cleanup the upcoming merge conflicts in next.  Thanks,
> 
> Alex
> 
> ---
> 
> Alex Williamson (3):
>       Revert "PCI/MSI: Remove unused get_cached_msi_msg()"
>       Revert "PCI/MSI: Rename __get_cached_msi_msg() to get_cached_msi_msg()"
>       Revert "PCI/MSI: Rename __read_msi_msg() to read_msi_msg()"
> 
> 
>  arch/ia64/kernel/msi_ia64.c          |    2 +-
>  arch/ia64/sn/kernel/msi_sn.c         |    2 +-
>  arch/powerpc/platforms/pseries/msi.c |    2 +-
>  arch/x86/kernel/apic/io_apic.c       |    2 +-
>  arch/x86/pci/xen.c                   |    2 +-
>  drivers/pci/msi.c                    |   11 +++++++++--
>  include/linux/msi.h                  |    5 +++--
>  7 files changed, 17 insertions(+), 9 deletions(-)
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