[PATCH] powerpc/powernv: Detach from PE on releasing PCI device

[PATCH] powerpc/powernv: Detach from PE on releasing PCI device

[Gavin Shan]

The PCI hotplug can be part of EEH error recovery. The @pdn and
the device's PE number aren't removed and added afterwords. The
PE number in @pdn should be set to an invalid one. Otherwise, the
PE's device count is decreased on removing devices while failing
to be increased on adding devices. It leads to unbalanced PE's
device count and make normal PCI hotplug path broken.

Fixes: c5f7700bbd2e ("powerpc/powernv: Dynamically release PE")
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index c16d790..e98f4a8 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3442,7 +3442,16 @@ static void pnv_pci_release_device(struct pci_dev *pdev)
 	if (!pdn || pdn->pe_number == IODA_INVALID_PE)
 		return;
 
+	/* PCI hotplug can happen as part of EEH error recovery. The @pdn
+	 * isn't removed and added afterwards in this scenario. We should
+	 * set the PE number in @pdn to an invalid one. Otherwise, the PE's
+	 * device count is decreased on removing devices while failing to
+	 * be increased on adding devices. It leads to unbalanced PE's device
+	 * count and eventually make normal PCI hotplug path broken.
+	 */
 	pe = &phb->ioda.pe_array[pdn->pe_number];
+	pdn->pe_number = IODA_INVALID_PE;
+
 	WARN_ON(--pe->device_count < 0);
 	if (pe->device_count == 0)
 		pnv_ioda_release_pe(pe);
-- 
2.1.0

Re: powerpc/powernv: Detach from PE on releasing PCI device

[Michael Ellerman]

On Tue, 2016-06-09 at 06:34:01 UTC, Gavin Shan wrote:
> The PCI hotplug can be part of EEH error recovery. The @pdn and
> the device's PE number aren't removed and added afterwords. The
> PE number in @pdn should be set to an invalid one. Otherwise, the
> PE's device count is decreased on removing devices while failing
> to be increased on adding devices. It leads to unbalanced PE's
> device count and make normal PCI hotplug path broken.
> 
> Fixes: c5f7700bbd2e ("powerpc/powernv: Dynamically release PE")
> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/29bf282dec94f6015a675c0076

cheers