Daniel De Graaf
2010-Sep-07 15:42 UTC
[Xen-devel] [PATCH] xenbus: add missing wakeup in concurrent read/write
If an application has a dedicated read thread watching xenbus and another thread writes an XS_WATCH message that generates a synthetic "OK" reply, this reply will be enqueued in the buffer without waking up the reader. This can cause a deadlock in the application if it then waits for the read thread to receive the queued message. Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov> _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jeremy Fitzhardinge
2010-Sep-07 23:34 UTC
Re: [Xen-devel] [PATCH] xenbus: add missing wakeup in concurrent read/write
On 09/08/2010 01:42 AM, Daniel De Graaf wrote:> If an application has a dedicated read thread watching xenbus and > another thread writes an XS_WATCH message that generates a synthetic > "OK" reply, this reply will be enqueued in the buffer without waking up > the reader. This can cause a deadlock in the application if it then > waits for the read thread to receive the queued message. > > Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>Thanks. Jun Zhu, does this fix the problem you were reporting? J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jun Zhu (Intern)
2010-Sep-08 10:51 UTC
RE: [Xen-devel] [PATCH] xenbus: add missing wakeup in concurrent read/write
That''s right! Thanks. Jun Zhu Citrix Systems UK ________________________________________ From: Jeremy Fitzhardinge [jeremy@goop.org] Sent: 07 September 2010 19:34 To: Daniel De Graaf Cc: xen-devel; Jun Zhu (Intern) Subject: Re: [Xen-devel] [PATCH] xenbus: add missing wakeup in concurrent read/write On 09/08/2010 01:42 AM, Daniel De Graaf wrote:> If an application has a dedicated read thread watching xenbus and > another thread writes an XS_WATCH message that generates a synthetic > "OK" reply, this reply will be enqueued in the buffer without waking up > the reader. This can cause a deadlock in the application if it then > waits for the read thread to receive the queued message. > > Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>Thanks. Jun Zhu, does this fix the problem you were reporting? J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel