[PATCH] nodedev: ignore EINVAL from libudev in udevEventHandleThread

[christian.ehrhardt at canonical.com]

From: Christian Ehrhardt <christian.ehrhardt at canonical.com>

Certiain udev entries might be of a size that makes libudev emit EINVAL
which right now leads to udevEventHandleThread exiting. Due to no more
handling events other elements of libvirt will start pushing for events
to be consumed which never happens causing a busy loop burning a cpu
without any gain.

After evaluation of the root cause of the example case discussed in
in #245 and a test run ignoring EINVAL it was considered safe to add
EINVAL to the ignored errnos to not exit udevEventHandleThread giving
it more resilience.

Fixes: #245

Signed-off-by: Christian Ehrhardt <christian.ehrhardt at canonical.com>
---
 src/node_device/node_device_udev.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 07c10f0d88..21fbcc2dca 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -1863,10 +1863,12 @@ udevEventHandleThread(void *opaque G_GNUC_UNUSED)
             }
 
             /* POSIX allows both EAGAIN and EWOULDBLOCK to be used
-             * interchangeably when the read would block or timeout was fired
+             * interchangeably when the read would block or timeout was fired.
+             * EINVAL might happen on too large udev entries, ignore those for
+             * the robustness of udevEventHandleThread.
              */
             VIR_WARNINGS_NO_WLOGICALOP_EQUAL_EXPR
-            if (errno != EAGAIN && errno != EWOULDBLOCK) {
+            if (errno != EAGAIN && errno != EWOULDBLOCK && errno != EINVAL) {
             VIR_WARNINGS_RESET
                 virReportSystemError(errno, "%s",
                                      _("failed to receive device from udev "
-- 
2.38.0