From c0b489c317a0cd3b709008d742d6653634455ded Mon Sep 17 00:00:00 2001
Message-Id: <c0b489c317a0cd3b709008d742d6653634455ded@dist-git>
From: "ning.bo" <ning.bo9@zte.com.cn>
Date: Mon, 29 May 2017 16:22:50 +0200
Subject: [PATCH] nodedev: Increase the netlink socket buffer size to the one
 used by udev

When a number of SRIOV VFs (up to 128 on Intel XL710) is created:
for i in `seq 0 1`; do
  echo 63 > /sys/class/net/<interface>/device/sriov_numvfs
done

libvirtd will then report "udev_monitor_receive_device returned NULL"
error because the netlink socket buffer is not big enough (using GDB on
libudev confirmed this with ENOBUFFS) and thus some udev events were
dropped. This results in some devices being missing in the nodedev-list
output. This patch overrides the system's rmem_max limit but for that,
we need to make sure we've got root privileges.

https://bugzilla.redhat.com/show_bug.cgi?id=1450960

Signed-off-by: ning.bo <ning.bo9@zte.com.cn>
Signed-off-by: Erik Skultety <eskultet@redhat.com>
(cherry picked from commit d1eea6c12aad5cb503562a52915138bf0d0a70a2)

https://bugzilla.redhat.com/show_bug.cgi?id=1442307
Signed-off-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/node_device/node_device_udev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 37528ee48..20c0fc837 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -1732,6 +1732,13 @@ static int nodeStateInitialize(bool privileged,
 
     udev_monitor_enable_receiving(priv->udev_monitor);
 
+    /* mimic udevd's behaviour and override the systems rmem_max limit in case
+     * there's a significant number of device 'add' events
+     */
+    if (geteuid() == 0)
+        udev_monitor_set_receive_buffer_size(priv->udev_monitor,
+                                             128 * 1024 * 1024);
+
     /* We register the monitor with the event callback so we are
      * notified by udev of device changes before we enumerate existing
      * devices because libvirt will simply recreate the device if we
-- 
2.13.0