PCI: pciehp: Avoid returning prematurely from sysfs requests

A sysfs request to enable or disable a PCIe hotplug slot should not
return before it has been carried out.  That is sought to be achieved by
waiting until the controller's "pending_events" have been cleared.

However the IRQ thread pciehp_ist() clears the "pending_events" before
it acts on them.  If pciehp_sysfs_enable_slot() / _disable_slot() happen
to check the "pending_events" after they have been cleared but while
pciehp_ist() is still running, the functions may return prematurely
with an incorrect return value.

Fix by introducing an "ist_running" flag which must be false before a sysfs
request is allowed to return.

Fixes: 32a8cef274fe ("PCI: pciehp: Enable/disable exclusively from IRQ thread")
Link: https://lore.kernel.org/linux-pci/[email protected]
Link: https://lore.kernel.org/r/4174210466e27eb7e2243dd1d801d5f75baaffd8.1565345211.git.lukas@wunner.de
Reported-and-tested-by: Xiongfeng Wang <[email protected]>
Signed-off-by: Lukas Wunner <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Cc: [email protected] # v4.19+

0 files changed, 0 insertions, 0 deletions