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authorDaniel De Graaf <dgdegra@tycho.nsa.gov>2010-09-07 17:42:18 +0200
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2010-09-08 15:18:02 +0200
commit76ce7618f9a24f7b13958c67f7d5ccfcdab71475 (patch)
treeef9dc704b151062924cc1ae1a43aeea2b3d76d5e /drivers/xen/xenfs
parentxenbus: allow any xenbus command over /proc/xen/xenbus (diff)
downloadlinux-76ce7618f9a24f7b13958c67f7d5ccfcdab71475.tar.xz
linux-76ce7618f9a24f7b13958c67f7d5ccfcdab71475.zip
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>
Diffstat (limited to 'drivers/xen/xenfs')
-rw-r--r--drivers/xen/xenfs/xenbus.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/xen/xenfs/xenbus.c b/drivers/xen/xenfs/xenbus.c
index 46cf4048e60e..c4c7db8363e7 100644
--- a/drivers/xen/xenfs/xenbus.c
+++ b/drivers/xen/xenfs/xenbus.c
@@ -405,6 +405,7 @@ static int xenbus_write_watch(unsigned msg_type, struct xenbus_file_priv *u)
mutex_lock(&u->reply_mutex);
rc = queue_reply(&u->read_buffers, &reply, sizeof(reply));
+ wake_up(&u->read_waitq);
mutex_unlock(&u->reply_mutex);
}