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> commit e752969f502a511e83f841aa01d6cd332e6d85a0 Author: Daniel De Graaf <dgdegra@tycho.nsa.gov> Date: Tue Sep 7 11:21:52 2010 -0400 xenbus: fix deadlock 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. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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@ -405,6 +405,7 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
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mutex_lock(&u->reply_mutex);
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rc = queue_reply(&u->read_buffers, &reply, sizeof(reply));
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wake_up(&u->read_waitq);
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mutex_unlock(&u->reply_mutex);
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}
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