| Message ID | 16fa7682a17785cd2580a12fed60e237f6f98826.camel@kernel.crashing.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc/powernv/pci: Work around races in PCI bridge enabling | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
| snowpatch_ozlabs/checkpatch | warning | Test checkpatch on branch next |
| snowpatch_ozlabs/build-ppc64le | fail | Test build-ppc64le on branch next |
| snowpatch_ozlabs/build-ppc64be | fail | Test build-ppc64be on branch next |
| snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
| snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
Hi Benjamin,
I love your patch! Yet something to improve:
[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.18 next-20180817]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Benjamin-Herrenschmidt/powerpc-powernv-pci-Work-around-races-in-PCI-bridge-enabling/20180817-113453
base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-defconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.2.0 make.cross ARCH=powerpc
All errors (new ones prefixed by >>):
arch/powerpc/platforms/powernv/pci-ioda.c: In function 'pnv_pci_enable_bridges':
>> arch/powerpc/platforms/powernv/pci-ioda.c:3262:18: error: unused variable 'pdev' [-Werror=unused-variable]
struct pci_dev *pdev;
^~~~
>> arch/powerpc/platforms/powernv/pci-ioda.c:3261:18: error: unused variable 'bus' [-Werror=unused-variable]
struct pci_bus *bus;
^~~
>> arch/powerpc/platforms/powernv/pci-ioda.c:3260:18: error: unused variable 'phb' [-Werror=unused-variable]
struct pnv_phb *phb;
^~~
cc1: all warnings being treated as errors
vim +/pdev +3262 arch/powerpc/platforms/powernv/pci-ioda.c
3256
3257 static void pnv_pci_enable_bridges(void)
3258 {
3259 struct pci_controller *hose;
> 3260 struct pnv_phb *phb;
> 3261 struct pci_bus *bus;
> 3262 struct pci_dev *pdev;
3263
3264 list_for_each_entry(hose, &hose_list, list_node)
3265 pnv_pci_enable_bridge(hose->bus);
3266 }
3267
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c index 70b2e1e0f23c..0975b0aaf210 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -3368,12 +3368,52 @@ static void pnv_pci_ioda_create_dbgfs(void) #endif /* CONFIG_DEBUG_FS */ } +static void pnv_pci_enable_bridge(struct pci_bus *bus) +{ + struct pci_dev *dev = bus->self; + struct pci_bus *child; + + /* Empty bus ? bail */ + if (list_empty(&bus->devices)) + return; + + /* + * If there's a bridge associated with that bus enable it. This works + * around races in the generic code if the enabling is done during + * parallel probing. This can be removed once those races have been + * fixed. + */ + if (dev) { + int rc = pci_enable_device(dev); + if (rc) + pci_err(dev, "Error enabling bridge (%d)\n", rc); + pci_set_master(dev); + } + + /* Perform the same to child busses */ + list_for_each_entry(child, &bus->children, node) + pnv_pci_enable_bridge(child); +} + +static void pnv_pci_enable_bridges(void) +{ + struct pci_controller *hose; + struct pnv_phb *phb; + struct pci_bus *bus; + struct pci_dev *pdev; + + list_for_each_entry(hose, &hose_list, list_node) + pnv_pci_enable_bridge(hose->bus); +} + static void pnv_pci_ioda_fixup(void) { pnv_pci_ioda_setup_PEs(); pnv_pci_ioda_setup_iommu_api(); pnv_pci_ioda_create_dbgfs(); + pnv_pci_enable_bridges(); + #ifdef CONFIG_EEH pnv_eeh_post_init(); #endif
The generic code is race when multiple children of a PCI bridge try to enable it simultaneously. This leads to drivers trying to access a device through a not-yet-enabled bridge, and this EEH errors under various circumstances when using parallel driver probing. There is work going on to fix that properly in the PCI core but it will take some time. x86 gets away with it because (outside of hotplug), the BIOS enables all the bridges at boot time. This patch does the same thing on powernv by enabling all bridges that have child devices at boot time, thus avoiding subsequent races. It's suitable for backporting to stable and distros, while the proper PCI fix will probably be significantly more invasive. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> CC: stable@vger.kernel.org ---