diff mbox series

[v2,2/2] powerpc/eeh: Release EEH device state synchronously

Message ID 6097b6ce84be2f36023d24d6a3b0774617ccb656.1587361657.git.sbobroff@linux.ibm.com (mailing list archive)
State Changes Requested
Headers show
Series powerpc/eeh: Release EEH device state synchronously | expand

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Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (a9aa21d05c33c556e48c5062b6632a9b94906570)
snowpatch_ozlabs/build-ppc64le success Build succeeded
snowpatch_ozlabs/build-ppc64be success Build succeeded
snowpatch_ozlabs/build-ppc64e success Build succeeded
snowpatch_ozlabs/build-pmac32 warning Upstream build failed, couldn't test patch
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 45 lines checked
snowpatch_ozlabs/needsstable success Patch has no Fixes tags

Commit Message

Sam Bobroff April 20, 2020, 5:47 a.m. UTC
EEH device state is currently removed (by eeh_remove_device()) during
the device release handler, which is invoked as the device's reference
count drops to zero. This may take some time, or forever, as other
threads may hold references.

However, the PCI device state is released synchronously by
pci_stop_and_remove_bus_device(). This mismatch causes problems, for
example the device may be re-discovered as a new device before the
release handler has been called, leaving the PCI and EEH state
mismatched.

So instead, call eeh_remove_device() from the bus device removal
handlers, which are called synchronously in the removal path.

Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
---
v2 - Added comment explaining why the add case can't be handled similarly to the remove case.

 arch/powerpc/kernel/eeh.c         | 31 +++++++++++++++++++++++++++++++
 arch/powerpc/kernel/pci-hotplug.c |  2 --
 2 files changed, 31 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 17cb3e9b5697..64361311bc8e 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -1106,6 +1106,37 @@  static int eeh_init(void)
 
 core_initcall_sync(eeh_init);
 
+static int eeh_device_notifier(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	struct device *dev = data;
+
+	switch (action) {
+	/*
+	 * Note: It's not possible to perform EEH device addition (i.e.
+	 * {pseries,pnv}_pcibios_bus_add_device()) here because it depends on
+	 * the device's resources, which have not yet been set up.
+	 */
+	case BUS_NOTIFY_DEL_DEVICE:
+		eeh_remove_device(to_pci_dev(dev));
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block eeh_device_nb = {
+	.notifier_call = eeh_device_notifier,
+};
+
+static __init int eeh_set_bus_notifier(void)
+{
+	bus_register_notifier(&pci_bus_type, &eeh_device_nb);
+	return 0;
+}
+arch_initcall(eeh_set_bus_notifier);
+
 /**
  * eeh_add_device_early - Enable EEH for the indicated device node
  * @pdn: PCI device node for which to set up EEH
diff --git a/arch/powerpc/kernel/pci-hotplug.c b/arch/powerpc/kernel/pci-hotplug.c
index d6a67f814983..28e9aa274f64 100644
--- a/arch/powerpc/kernel/pci-hotplug.c
+++ b/arch/powerpc/kernel/pci-hotplug.c
@@ -57,8 +57,6 @@  void pcibios_release_device(struct pci_dev *dev)
 	struct pci_controller *phb = pci_bus_to_host(dev->bus);
 	struct pci_dn *pdn = pci_get_pdn(dev);
 
-	eeh_remove_device(dev);
-
 	if (phb->controller_ops.release_device)
 		phb->controller_ops.release_device(dev);