Michael Ellerman wrote:
On Wed, 2009-07-15 at 14:43 -0700, Mike Mason wrote:
This patch increments the device_node reference counter when an EEH
error occurs and decrements the counter when the event has been
handled. This is to prevent the device_node from being released until
eeh_event_handler() has had a chance to deal with the event. We've
seen cases where the device_node is released too soon when an EEH
event occurs during a dlpar remove, causing the event handler to
attempt to access bad memory locations.
Please review and let me know of any concerns.
Taking a reference sounds sane, but ...
Signed-off-by: Mike Mason <mm...@us.ibm.com>
--- a/arch/powerpc/platforms/pseries/eeh_event.c 2008-10-09
15:13:53.000000000 -0700
+++ b/arch/powerpc/platforms/pseries/eeh_event.c 2009-07-14
14:14:00.000000000 -0700
@@ -75,6 +75,14 @@ static int eeh_event_handler(void * dumm
if (event == NULL)
return 0;
+ /* EEH holds a reference to the device_node, so if it
+ * equals 1 it's no longer valid and the event should
+ * be ignored */
+ if (atomic_read(&event->dn->kref.refcount) == 1) {
+ of_node_put(event->dn);
+ return 0;
+ }
That's really gross :)
Agreed. I'll look for another way to determine if device is gone and the event
should be ignored. Suggestions are welcome :-)
And what happens if the refcount goes to 1 just after the check? ie.
here.
/* Serialize processing of EEH events */
mutex_lock(&eeh_event_mutex);
eeh_mark_slot(event->dn, EEH_MODE_RECOVERING);
cheers
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