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Re: [Xen-devel] [PATCH] xenconsole: add file lock to xenconsole

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xenconsole: add file lock to xenconsole
From: Yufang Zhang <yufang521247@xxxxxxxxx>
Date: Fri, 27 May 2011 11:20:54 +0800
Cc: pbonzini@xxxxxxxxxx, Yufang Zhang <yuzhang@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, stefano.stabellini@xxxxxxxxxxxxx
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On 05/25/2011 01:09 AM, Ian Jackson wrote:
Yufang Zhang writes ("[Xen-devel] [PATCH] xenconsole: add file lock to 
This patch add a file lock to xenconsole for each console id, so
that only one console could be attached to a guest at a time.
Otherwise, consoles would get stuck and print strange outputs.
If only we had a better console protocol, it would be possible to
attach multiple times.  Oh well.  In the meantime your semantic change
is sensible.


+static int console_locked(const char *file)
+        int fd;
You need to use the same indent level and coding style as the
surrounding code.

+        sprintf(buf, "/tmp/xenconsole-%d-%d", domid, num);
The lockfile should be in /var/run/xen.  You should use snprintf.

Thanks Ian. Version2 patch has been sent, please review.

What arrangements do you plan to make for cleaning up stale lockfiles
(which I think will be left behind if the xenconsole client crashes) ?
Are we just going to rely on them being removed at reboot and apart
from that let them accumulate a bit ?

Considering the lock files are just blank and can be reused, leaving them behind is not that bad?


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