possible race condition in kdbus:domain

[John de la Garza]

kdbus_domain_new() calls device_register which sends a message to udev
to create the device file which is done asynchronously by udev.  If one
calls close on the file descriptor immediately after creating a domain
the close call calls kdbus_domain_disconnect which calls device_unregister
before device_register's udev call to create the file finished resulting
in the file not getting removed from /dev/kdbus.

Adding msleep(5) fixes this in some cases do does msleep(0).

I'm thinking this may not always work and kdbus_domain_new should
explicitly wait till the file shows up in /dev before returning.

Is it safe to assume udev will finish in a fixed time or should
it be checked?

Or may there is another way to address this... any ideas?

Signed-off-by: John de la Garza <john at jjdev.com>
---
 domain.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/domain.c b/domain.c
index ee77f36..f53d18b 100644
--- a/domain.c
+++ b/domain.c
@@ -19,6 +19,7 @@
 #include <linux/sizes.h>
 #include <linux/slab.h>
 #include <linux/uaccess.h>
+#include <linux/delay.h>
 
 #include "bus.h"
 #include "defaults.h"
@@ -356,6 +357,10 @@ int kdbus_domain_new(struct kdbus_domain *parent, const char *name,
 		mutex_unlock(&parent->lock);
 
 	*domain = d;
+
+	/* allow udev time to create file */
+	msleep(5);
+
 	return 0;
 
 exit_unlock:
-- 
1.7.10.4