powerpc/eeh_sysfs: Make clearing EEH_DEV_SYSFS saner

The eeh_sysfs_remove_device() function is supposed to clear the
EEH_DEV_SYSFS flag since it indicates the EEH sysfs entries have been added
for a pci_dev.

When the sysfs files are removed eeh_remove_device() the eeh_dev and the
pci_dev have already been de-associated. This then causes the
pci_dev_to_eeh_dev() call in eeh_sysfs_remove_device() to return NULL so
the flag can't be cleared from the still-live eeh_dev. This problem is
worked around in the caller by clearing the flag manually. However, this
behaviour doesn't make a whole lot of sense, so this patch fixes it by:

a) Re-ordering eeh_remove_device() so that eeh_sysfs_remove_device() is
   called before de-associating the pci_dev and eeh_dev.

b) Making eeh_sysfs_remove_device() emit a warning if there's no
   corresponding eeh_dev for a pci_dev. The paths where the sysfs
   files are only reachable if EEH was setup for the device
   for the device in the first place so hitting this warning
   indicates a programming error.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Sam Bobroff <sbobroff@linux.ibm.com>
Tested-by: Sam Bobroff <sbobroff@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190715085612.8802-6-oohall@gmail.com

1 files changed, 8 insertions, 7 deletions

diff --git a/arch/powerpc/kernel/eeh_sysfs.c b/arch/powerpc/kernel/eeh_sysfs.c
index a6638ea54797..4fb0f1e1017a 100644
--- a/arch/powerpc/kernel/eeh_sysfs.c
+++ b/arch/powerpc/kernel/eeh_sysfs.c
@@ -159,22 +159,23 @@ void eeh_sysfs_remove_device(struct pci_dev *pdev)
 {
 	struct eeh_dev *edev = pci_dev_to_eeh_dev(pdev);
 
+	if (!edev) {
+		WARN_ON(eeh_enabled());
+		return;
+	}
+
+	edev->mode &= ~EEH_DEV_SYSFS;
+
 	/*
 	 * The parent directory might have been removed. We needn't
 	 * continue for that case.
 	 */
-	if (!pdev->dev.kobj.sd) {
-		if (edev)
-			edev->mode &= ~EEH_DEV_SYSFS;
+	if (!pdev->dev.kobj.sd)
 		return;
-	}
 
 	device_remove_file(&pdev->dev, &dev_attr_eeh_mode);
 	device_remove_file(&pdev->dev, &dev_attr_eeh_pe_config_addr);
 	device_remove_file(&pdev->dev, &dev_attr_eeh_pe_state);
 
 	eeh_notify_resume_remove(pdev);
-
-	if (edev)
-		edev->mode &= ~EEH_DEV_SYSFS;
 }