On Mon, Jul 10, 2017 at 04:49:24PM +0100, Lorenzo Pieralisi wrote:
> On Mon, Jul 10, 2017 at 09:55:53AM -0500, Bjorn Helgaas wrote:
> > On Mon, Jul 10, 2017 at 01:34:09PM +0100, Lorenzo Pieralisi wrote:
> > > If pci_scan_root_bus() fails (ie returns NULL) pcibios_scan_bus() must
> > > return immediately since the struct pci_bus pointer it returns is not
> > > valid and cannot be used.
> > >
> > > Move code checking the pci_scan_root_bus() return value to reinstate
> > > proper pcibios_scanbus() error path behaviour.
> > >
> > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> > > Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> > > Cc: Paul Burton <paul.burton@xxxxxxxxxx>
> > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> >
> > I agree this is certainly broken. In fact, I think I broke it with
> > 9e808eb6a768 ("PCI: Cleanup control flow") in 2015. So probably v4.14
> > material?
>
> Yes that makes sense, I spotted it since I am preparing patches to
> remove pci_fixup_irqs() from the kernel (by removing it from all arches
> that still use it), I think that technically:
>
> 88555b481958 ("MIPS: PCI: Support for CONFIG_PCI_DOMAINS_GENERIC")
>
> created a possible breakage (ie by using the possible NULL bus pointer),
> if you merge it in one branch for 4.14 I will base the pci_fixup_irqs()
> removal on top of it and post the series, just let me know please.
Ah, you're right. I created some poor style (checking the return
value after intervening code) with 9e808eb6a768, and then 88555b481958
fell into the trap I had laid.
I put this on pci/irq-fixups for a continuation of your work and
started it off with this patch.
I will rebase the branch after -rc1, but that shouldn't be a problem
for you because I normally apply patches from email rather than
pulling them directly. I'll be on vacation July 14-28, so that
probably won't happen until August.
Thanks!
> > > ---
> > > arch/mips/pci/pci-legacy.c | 10 +++++-----
> > > 1 file changed, 5 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/arch/mips/pci/pci-legacy.c b/arch/mips/pci/pci-legacy.c
> > > index 174575a..71d62f8 100644
> > > --- a/arch/mips/pci/pci-legacy.c
> > > +++ b/arch/mips/pci/pci-legacy.c
> > > @@ -89,16 +89,16 @@ static void pcibios_scanbus(struct pci_controller *hose)
> > > pci_add_resource(&resources, hose->busn_resource);
> > > bus = pci_scan_root_bus(NULL, next_busno, hose->pci_ops, hose,
> > > &resources);
> > > - hose->bus = bus;
> > > -
> > > - need_domain_info = need_domain_info || pci_domain_nr(bus);
> > > - set_pci_need_domain_info(hose, need_domain_info);
> > > -
> > > if (!bus) {
> > > pci_free_resource_list(&resources);
> > > return;
> > > }
> > >
> > > + hose->bus = bus;
> > > +
> > > + need_domain_info = need_domain_info || pci_domain_nr(bus);
> > > + set_pci_need_domain_info(hose, need_domain_info);
> > > +
> > > next_busno = bus->busn_res.end + 1;
> > > /* Don't allow 8-bit bus number overflow inside the hose -
> > > reserve some space for bridges. */
> > > --
> > > 2.10.0
> > >
