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# HG changeset patch
# User kfraser@localhost.localdomain
# Date 1180016489 -3600
# Node ID 3ef4a4d8213061fe14d905e89594c99d0b9cb605
# Parent 6a4af9502b4da269388a60416a7cca0ecadb3bb3
xend: Fix for removing devices at save/destroy domain.

The function XendDomainInfo:_releaseDevices() is called during the
save/destroy phase of a domain. It made some attempt to clean up the
devices, but wasn't complete, leaving dangling devices in the
xenstore. Not a big problem with normal use of Xen, but a buildup over
a large number of save/destroy instances, it would make the xenstore
database grow quite large, which in turn meant swap-thrashing in Dom0.

This patch makes use of the destroyDevices() function in
XendDomainInfo. This function needed some re-writing to make it work
correctly - I think it had some old code (not sure how old, as xm
annotate says that it's changeset 12071, but that, I think, is when it
was split out from XendDomain.py, rather than when it was created).

I have tested this over a few hundred save/restore cycles [.two domains
constantly saved/restored with a short sleep to let them process some
work] combined with a loop of "xenstore-ls|wc". The output of the
latter is pretty much constant (it obviously varies a bit depending on
when in the save/restore cycle it hits). Previously, it would increase
by some 10 lines or so per save/restore cycle.

Signed-off-by: Mats Petersson <mats.petersson@amd.com>
---
tools/python/xen/xend/XendDomainInfo.py | 49 ++++++++++++++++++--------------
1 files changed, 29 insertions(+), 20 deletions(-)

diff -r 6a4af9502b4d -r 3ef4a4d82130 tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py Thu May 24 15:13:13 2007 +0100
+++ b/tools/python/xen/xend/XendDomainInfo.py Thu May 24 15:21:29 2007 +0100
@@ -546,20 +546,30 @@ class XendDomainInfo:
self.getDeviceController(devclass).waitForDevices()

def destroyDevice(self, deviceClass, devid, force = False):
+ found = True # Assume devid is an integer.
try:
devid = int(devid)
except ValueError:
# devid is not a number, let's search for it in xenstore.
devicePath = '%s/device/%s' % (self.dompath, deviceClass)
+ found = False
for entry in xstransact.List(devicePath):
+ log.debug("Attempting to find devid at %s/%s", devicePath, entry)
backend = xstransact.Read('%s/%s' % (devicePath, entry),
"backend")
- devName = xstransact.Read(backend, "dev")
- if devName == devid:
- # We found the integer matching our devid, use it instead
- devid = entry
- break
-
+ if backend != None:
+ devName = '%s/%s' % (deviceClass, entry)
+ log.debug("devName=%s", devName)
+ if devName == devid:
+ # We found the integer matching our devid, use it instead
+ devid = int(entry)
+ found = True
+ break
+
+ if not found:
+ log.debug("Could not find the device %s", devid)
+ return None
+ log.debug("devid = %s", devid)
return self.getDeviceController(deviceClass).destroyDevice(devid, force)

def getDeviceSxprs(self, deviceClass):
@@ -1338,20 +1348,19 @@ class XendDomainInfo:
self.image.destroy(suspend)
return

- while True:
- t = xstransact("%s/device" % self.dompath)
- for devclass in XendDevices.valid_devices():
- for dev in t.list(devclass):
- try:
- t.remove(dev)
- except:
- # Log and swallow any exceptions in removal --
- # there's nothing more we can do.
- log.exception(
- "Device release failed: %s; %s; %s",
- self.info['name_label'], devclass, dev)
- if t.commit():
- break
+ t = xstransact("%s/device" % self.dompath)
+ for devclass in XendDevices.valid_devices():
+ for dev in t.list(devclass):
+ try:
+ log.debug("Removing %s", dev);
+ self.destroyDevice(devclass, dev, False);
+ except:
+ # Log and swallow any exceptions in removal --
+ # there's nothing more we can do.
+ log.exception("Device release failed: %s; %s; %s",
+ self.info['name_label'], devclass, dev)
+
+

def getDeviceController(self, name):
"""Get the device controller for this domain, and if it

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