kdump: add udev events for memory online/offline

Currently no udev events for memory hotplug "online" and "offline" are
generated:

# udevadm monitor
# echo offline > /sys/devices/system/memory/memory4/state
==> No event

When kdump is loaded, kexec detects the current memory configuration and
stores it in the pre-allocated ELF core header.  Therefore, for kdump it
is necessary to reload the kdump kernel with kexec when the memory
configuration changes (e.g.  for online/offline hotplug memory).

In order to do this automatically, udev rules should be used.  This kernel
patch adds udev events for "online" and "offline".  Together with this
kernel patch, the following udev rules for online/offline have to be added
to "/etc/udev/rules.d/98-kexec.rules":

SUBSYSTEM=="memory", ACTION=="online", PROGRAM="/etc/init.d/kdump restart"
SUBSYSTEM=="memory", ACTION=="offline", PROGRAM="/etc/init.d/kdump restart"

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 8272d92d22c0404412903f2948694a545d263bd9..9408829b46b41c035bc415d767cf94d7e6aec170 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -313,11 +313,22 @@ static int memory_block_change_state(struct memory_block *mem,
 
        ret = memory_block_action(mem->start_section_nr, to_state);
 
-       if (ret)
+       if (ret) {
                mem->state = from_state_req;
-       else
-               mem->state = to_state;
+               goto out;
+       }
 
+       mem->state = to_state;
+       switch (mem->state) {
+       case MEM_OFFLINE:
+               kobject_uevent(&mem->sysdev.kobj, KOBJ_OFFLINE);
+               break;
+       case MEM_ONLINE:
+               kobject_uevent(&mem->sysdev.kobj, KOBJ_ONLINE);
+               break;
+       default:
+               break;
+       }
 out:
        mutex_unlock(&mem->state_mutex);
        return ret;