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systemd/1011-check-4-valid-kmsg-device.patch

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From: Werner Fink <werner@suse.de>
Date: Thu, 21 Nov 2013 11:50:32 +0000
Subject: [PATCH] Avoid busy systemd-journald
Avoid a busy systemd-journald due polling a broken /dec/kmsg in lxc
environments.
---
journald-kmsg.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
Index: systemd-208/src/journal/journald-kmsg.c
===================================================================
--- systemd-208/src/journal/journald-kmsg.c
+++ systemd-208/src/journal/journald-kmsg.c 2013-11-21 13:30:22.930735683 +0000
@@ -23,7 +23,9 @@
#include <sys/epoll.h>
#include <fcntl.h>
#include <sys/mman.h>
+#include <sys/stat.h>
#include <sys/socket.h>
+#include <sys/types.h>
#include <systemd/sd-messages.h>
#include <libudev.h>
@@ -377,20 +379,43 @@ int server_flush_dev_kmsg(Server *s) {
int server_open_dev_kmsg(Server *s) {
struct epoll_event ev;
+ struct stat st;
assert(s);
s->dev_kmsg_fd = open("/dev/kmsg", O_RDWR|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (s->dev_kmsg_fd < 0) {
- log_warning("Failed to open /dev/kmsg, ignoring: %m");
+ /* Do not warn as it may not exists in LXC environments */
+ if (errno != ENOENT)
+ log_warning("Failed to open /dev/kmsg, ignoring: %m");
return 0;
}
+ if (fstat(s->dev_kmsg_fd, &st) < 0) {
+ log_error("Failed to stat /dev/kmsg fd, ignoring: %m");
+ close_nointr_nofail(s->dev_kmsg_fd);
+ s->dev_kmsg_fd = -1;
+ return 0;
+ }
+
+ if (!S_ISCHR(st.st_mode) || major(st.st_rdev) != 1 || minor(st.st_rdev) != 11) {
+ int old_errno = errno;
+ errno = ENODEV;
+ log_warning("Irregular device /dev/kmsg, ignoring: %m");
+ errno = old_errno;
+ close_nointr_nofail(s->dev_kmsg_fd);
+ s->dev_kmsg_fd = -1;
+ return 0;
+ }
+
zero(ev);
ev.events = EPOLLIN;
ev.data.fd = s->dev_kmsg_fd;
if (epoll_ctl(s->epoll_fd, EPOLL_CTL_ADD, s->dev_kmsg_fd, &ev) < 0) {
+ close_nointr_nofail(s->dev_kmsg_fd);
+ s->dev_kmsg_fd = -1;
+
/* This will fail with EPERM on older kernels where
* /dev/kmsg is not readable. */
if (errno == EPERM)