On Thu, May 12, 2022 at 04:56:42PM +0200, Niklas Schnelle
wrote:> On Thu, 2022-05-05 at 10:38 +0200, Niklas Schnelle wrote:
> > While determining the next PCI function is factored out of
> > pci_scan_slot() into next_fn() the former still handles the first
> > function as a special case. This duplicates the code from the scan
loop.
> >
> > Furthermore the non ARI branch of next_fn() is generally hard to
> > understand and especially the check for multifunction devices is
hidden
> > in the handling of NULL devices for non-contiguous multifunction. It
> > also signals that no further functions need to be scanned by returning
> > 0 via wraparound and this is a valid function number.
> >
> > Improve upon this by transforming the conditions in next_fn() to be
> > easier to understand.
> >
> > By changing next_fn() to return -ENODEV instead of 0 when there is no
> > next function we can then handle the initial function inside the loop
> > and deduplicate the shared handling. This also makes it more explicit
> > that only function 0 must exist.
> >
> > No functional change is intended.
> >
> > Cc: Jan Kiszka <jan.kiszka at siemens.com>
> > Signed-off-by: Niklas Schnelle <schnelle at linux.ibm.com>
> > ---
>
> Friendly ping :-)
Thanks and sorry for the delay. I'm off today for my daughter's
wedding reception but will get back to it next week. Just to expose
some of my thought process (and not to request more work from you!)
I've been wondering whether b1bd58e448f2 ("PCI: Consolidate
"next-function" functions") is really causing us more trouble
than
it's worth. In some ways that makes the single next-function harder
to read. But I guess the hypervisor special case is not exactly a
"next-function" thing -- it's a "keep scanning even if
there's no fn
0" thing.
Bjorn