On Sat, 2019-06-29 at 10:08 +0200, Thomas Gleixner wrote:
> Megha,
>
> On Fri, 21 Jun 2019, Megha Dey wrote:
> >
> > +static int free_msi_irqs_grp(struct pci_dev *dev, int group_id)
> > +{
> >
> > +
> > + for_each_pci_msi_entry(entry, dev) {
> > + if (entry->group_id == group_id && entry->irq)
> > + for (i = 0; i < entry->nvec_used; i++)
> > + BUG_ON(irq_has_action(entry->irq +
> > i));
> BUG_ON is wrong here. This can and must be handled gracefully.
>
Hmm, I reused this code from the 'free_msi_irqs' function. I am not
sure why it is wrong to use BUG_ON here but ok to use it there, please
let me know.
> >
> > + }
> > +
> > + pci_msi_teardown_msi_irqs_grp(dev, group_id);
> > +
> > + list_for_each_entry_safe(entry, tmp, msi_list, list) {
> > + if (entry->group_id == group_id) {
> > + clear_bit(entry->msi_attrib.entry_nr, dev-
> > >entry);
> > + list_del(&entry->list);
> > + free_msi_entry(entry);
> > + }
> > + }
> > +
> > + list_for_each_entry_safe(msix_sysfs_entry, tmp_msix,
> > pci_msix, list) {
> > + if (msix_sysfs_entry->group_id == group_id) {
> Again. Proper group management makes all of that just straight
> forward and
> not yet another special case.
>
Yeah, the new proposal of having a group_list would get rid of this.
> >
> > + msi_attrs = msix_sysfs_entry-
> > >msi_irq_group->attrs;
> >
> > +static void pci_msix_shutdown_grp(struct pci_dev *dev, int
> > group_id)
> > +{
> > + struct msi_desc *entry;
> > + int grp_present = 0;
> > +
> > + if (pci_dev_is_disconnected(dev)) {
> > + dev->msix_enabled = 0;
> Huch? What's that? I can't figure out why this is needed and of
> course it
> completely lacks a comment explaining this.
>
Again, I have reused this code from the pci_msix_shutdown() function.
So for the group case, this is not required?
> >
> > + return;
> > + }
> > +
> > + /* Return the device with MSI-X masked as initial states
> > */
> > + for_each_pci_msi_entry(entry, dev) {
> > + if (entry->group_id == group_id) {
> > + /* Keep cached states to be restored */
> > + __pci_msix_desc_mask_irq(entry, 1);
> > + grp_present = 1;
> > + }
> > + }
> > +
> > + if (!grp_present) {
> > + pci_err(dev, "Group to be disabled not
> > present\n");
> > + return;
> So you print an error and silently return
>
This is a void function, hence no error value can be returned. What do
you think is the right thing to do if someone wants to delete a group
which is not present?
> >
> > + }
> > +}
> > +
> > +int pci_disable_msix_grp(struct pci_dev *dev, int group_id)
> > +{
> > + int num_vecs;
> > +
> > + if (!pci_msi_enable || !dev)
> > + return -EINVAL;
> > +
> > + pci_msix_shutdown_grp(dev, group_id);
> > + num_vecs = free_msi_irqs_grp(dev, group_id);
> just to call in another function which has to do the same group_id
> lookup
> muck again.
Even with the new proposal, we are to have 2 sets of functions: one to
delete all the msic_desc entries associated with the device, and the
other to delete those only belonging a 'user specified' group. So we do
need to pass a group_id to these functions right? Yes, internally the
deletion would be straightforward with the new approach.
>
> >
> > +
> > + return num_vecs;
> > +}
> > +EXPORT_SYMBOL(pci_disable_msix_grp);
> Why is this exposed ?
>
As before, I just followed what pci_disable_msix() did <sigh>. Looks
like pci_disable_msix is called from a variety of drivers, thus it is
exposed. Currently, no one will use the pci_disable_msix_grp()
externally, thus it need not be exposed for now.
> Thanks,
>
> tglx
