On Mon, 21 Jun 2021 08:01:35 -0500
Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
> On Sat, Jun 19, 2021 at 07:29:20PM +0530, Amey Narkhede wrote:
> > On 21/06/18 03:00PM, Bjorn Helgaas wrote:
> > > On Tue, Jun 08, 2021 at 11:18:53AM +0530, Amey Narkhede wrote:
> > > > + while ((name = strsep(&options, ",")) != NULL) {
> > > > + if (sysfs_streq(name, ""))
> > > > + continue;
> > > > +
> > > > + name = strim(name);
> > > > +
> > > > + for (i = 0; i < PCI_RESET_METHODS_NUM; i++) {
> > > > + if (reset_methods[i] &&
> > > > + sysfs_streq(name, pci_reset_fn_methods[i].name)) {
> > > > + reset_methods[i] = prio--;
> > > > + break;
> > > > + }
> > > > + }
> > > > +
> > > > + if (i == PCI_RESET_METHODS_NUM) {
> > > > + kfree(options);
> > > > + return -EINVAL;
> > > > + }
> > > > + }
> > > > +
> > > > + if (reset_methods[0] &&
> > > > + reset_methods[0] != PCI_RESET_METHODS_NUM)
> > > > + pci_warn(pdev, "Device specific reset disabled/de-prioritized by user");
> > >
> > > Is there a specific reason for this warning? Is it just telling the
> > > user that he might have shot himself in the foot? Not sure that's
> > > necessary.
> > >
> > I think generally presence of device specific reset method means other
> > methods are potentially broken. Is it okay to skip this?
>
> We might want a warning at reset-time if all the methods failed,
> because that means we may leak state between users. Maybe we also
> want one here, if *all* reset methods are disabled. I don't really
> like special treatment of device-specific methods here because it
> depends on the assumption that "device-specific means all other resets
> are broken." That's hard to maintain.
I'd say the device specific reset is special. The device itself can
support a number of resets and they're theoretically all equivalent,
it's a policy decision which to use. But the device specific reset is
a software provided reset. Someone has specifically gone to the
trouble to create a reset mechanism that is in some way better than the
other methods. Not using that one by default sure feels like something
worthy of leaving a breadcrumb in dmesg for debugging. Thanks,
Alex
