Re: [PATCH 3 of 3] remus: handle exceptions while installing/unstalling net buffer

[Shriram Rajagopalan <rshriram@cs.ubc.ca>]

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On Wed, Jun 22, 2011 at 9:37 AM, Shriram Rajagopalan <rshriram@cs.ubc.ca>wrote:

> # HG changeset patch
> # User Shriram Rajagopalan <rshriram@cs.ubc.ca>
> # Date 1308749695 25200
> # Node ID 9eed27800ff6a2e6d73f138f20af072c1b41925e
> # Parent  794ead1a2be0578d70c38f006e7ab61c7abe9203
> remus: handle exceptions while installing/unstalling net buffer
>
> Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
>
> diff -r 794ead1a2be0 -r 9eed27800ff6 tools/python/xen/remus/device.py
> --- a/tools/python/xen/remus/device.py  Tue Jun 21 12:11:44 2011 -0700
> +++ b/tools/python/xen/remus/device.py  Wed Jun 22 06:34:55 2011 -0700
> @@ -169,15 +169,25 @@
>         self.vif = vif
>         # voodoo from
> http://www.linuxfoundation.org/collaborate/workgroups/networking/ifb#Typical_Usage
>         util.runcmd('ip link set %s up' % self.devname)
> -        util.runcmd('tc qdisc add dev %s ingress' % vif.dev)
> +        try:
> +            util.runcmd('tc qdisc add dev %s ingress' % vif.dev)
> +        except util.PipeException, e:
> +            # check if error indicates that ingress qdisc
> +            # already exists on the vif. If so, ignore it.
> +            ignoreme = 'RTNETLINK answers: File exists'
> +            if ignoreme in str(e):
> +                pass
> +            else:
> +                raise e
>         util.runcmd('tc filter add dev %s parent ffff: proto ip pref 10 '
>                     'u32 match u32 0 0 action mirred egress redirect '
>                     'dev %s' % (vif.dev, self.devname))
>
>     def uninstall(self):
> -        util.runcmd('tc filter del dev %s parent ffff: proto ip pref 10
> u32' \
> -                        % self.vif.dev)
> -        util.runcmd('tc qdisc del dev %s ingress' % self.vif.dev)
> +        try:
> +            util.runcmd('tc qdisc del dev %s ingress' % self.vif.dev)
> +        except util.PipeException, e:
> +            pass
>         util.runcmd('ip link set %s down' % self.devname)
>
>  class IMQBuffer(Netbuf):
> @@ -373,9 +383,15 @@
>
>     def uninstall(self):
>         if self.installed:
> -            req = qdisc.delrequest(self.bufdevno, self.handle)
> -            self.rth.talk(req.pack())
> +            try:
> +                req = qdisc.delrequest(self.bufdevno, self.handle)
> +                self.rth.talk(req.pack())
> +            except IOError, e:
> +                pass
>             self.installed = False
>
> -        self.bufdev.uninstall()
> -        self.pool.put(self.bufdev)
> +            try:
> +                self.bufdev.uninstall()
> +            except util.PipeException, e:
> +                pass
> +            self.pool.put(self.bufdev)
> diff -r 794ead1a2be0 -r 9eed27800ff6 tools/python/xen/remus/util.py
> --- a/tools/python/xen/remus/util.py    Tue Jun 21 12:11:44 2011 -0700
> +++ b/tools/python/xen/remus/util.py    Wed Jun 22 06:34:55 2011 -0700
> @@ -65,8 +65,10 @@
>         proc.wait()
>         if proc.returncode:
>             print ' '.join(args)
> -            print stderr.strip()
> -            raise PipeException('%s failed' % args[0], proc.returncode)
> +            errmsg = stderr.strip()
> +            print errmsg
> +            raise PipeException('%s failed (errmsg: %s)' % (args[0],
> errmsg),
> +                                proc.returncode)
>         return stdout
>     except (OSError, IOError), inst:
>         raise PipeException('could not run %s' % args[0], inst.errno)
>
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>

As Brendan pointed out, 90% of what I proposed to remove
in patches 1 & 2 of this series might be useful for folks who want to hack
on Remus
or live migration code. I ll do the clean up later, more carefully.

Ian, if you have no objection to this patch, could you take in this one
alone and
reject patches 1 & 2? Or do you want me to send this one separately again?

shriram

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