On Wed, Jul 28, 2021 at 11:15:19PM +0530, Amey Narkhede wrote:
> On 21/07/27 05:59PM, Bjorn Helgaas wrote:
> > On Fri, Jul 09, 2021 at 06:08:07PM +0530, Amey Narkhede wrote:
> > > Introduce a new array reset_methods in struct pci_dev to keep track of
> > > reset mechanisms supported by the device and their ordering.
> > >
> > > Also refactor probing and reset functions to take advantage of calling
> > > convention of reset functions.
> > >
> > > Co-developed-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > > Signed-off-by: Amey Narkhede <ameynarkhede03@xxxxxxxxx>
> > > ---
> > > drivers/pci/pci.c | 92 ++++++++++++++++++++++++++-------------------
> > > drivers/pci/pci.h | 9 ++++-
> > > drivers/pci/probe.c | 5 +--
> > > include/linux/pci.h | 7 ++++
> > > 4 files changed, 70 insertions(+), 43 deletions(-)
> > >
> >
> [...]
> > > + BUILD_BUG_ON(ARRAY_SIZE(pci_reset_fn_methods) != PCI_NUM_RESET_METHODS);
> > >
> > > might_sleep();
> > >
> > > - rc = pci_dev_specific_reset(dev, 1);
> > > - if (rc != -ENOTTY)
> > > - return rc;
> > > - rc = pcie_reset_flr(dev, 1);
> > > - if (rc != -ENOTTY)
> > > - return rc;
> > > - rc = pci_af_flr(dev, 1);
> > > - if (rc != -ENOTTY)
> > > - return rc;
> > > - rc = pci_pm_reset(dev, 1);
> > > - if (rc != -ENOTTY)
> > > - return rc;
> > > + for (i = 1; i < PCI_NUM_RESET_METHODS; i++) {
> > > + rc = pci_reset_fn_methods[i].reset_fn(dev, 1);
> > > + if (!rc)
> > > + reset_methods[n++] = i;
> >
> > Why do we need this local reset_methods[] array? Can we just fill
> > in dev->reset_methods[] directly and skip the memcpy() below?
> >
> This is for avoiding caching of previously supported reset methods.
> Is it okay if I use memset(dev->reset_methods, 0,
> sizeof(dev->reset_methods)) instead to clear the values in
> dev->reset_methods?
I don't think there's ever a case where you look at a
dev->reset_methods[] element past a zero value, so we shouldn't care
about any previously-supported methods left in the array.
If we *do* look at something past a zero value, why do we do that? It
sounds like it would be a bug.
> > > + else if (rc != -ENOTTY)
> > > + break;
> > > + }
> > >
> > > - return pci_reset_bus_function(dev, 1);
> > > + memcpy(dev->reset_methods, reset_methods, sizeof(reset_methods));
> > > }
> > >
> > > /**
> [...]
