| Message ID | 20170710123409.9043-2-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
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@arm.com> > Cc: Ralf Baechle <ralf@linux-mips.org> > Cc: Paul Burton <paul.burton@imgtec.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> 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? > --- > 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 >
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@arm.com> > > Cc: Ralf Baechle <ralf@linux-mips.org> > > Cc: Paul Burton <paul.burton@imgtec.com> > > Cc: Bjorn Helgaas <bhelgaas@google.com> > > 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. Thanks ! Lorenzo > > --- > > 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 > >
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@arm.com> > > > Cc: Ralf Baechle <ralf@linux-mips.org> > > > Cc: Paul Burton <paul.burton@imgtec.com> > > > Cc: Bjorn Helgaas <bhelgaas@google.com> > > > > 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 > > >
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. */
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@arm.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@imgtec.com> Cc: Bjorn Helgaas <bhelgaas@google.com> --- arch/mips/pci/pci-legacy.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)