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authorRobin H. Johnson <robbat2@gentoo.org>2011-01-18 01:26:34 +0000
committerRobin H. Johnson <robbat2@gentoo.org>2011-01-18 01:29:09 +0000
commit80853f5dbc3a42419ac359ee035ebc76de86d3b3 (patch)
treed99200248b7e427d3f1c85a5d9d0b639859afe80 /sh
parent9ce957c3e722e3851a191b901bb377c13a1bbec1 (diff)
sh/init: Detect a mounted /proc without sleeping
Previously we checked if /proc was alive by reading /proc/uptime twice with a 1 second sleep between calls, so that it had time to update. This got a complaint of an entire 1 second delay, so we improve the check to be much faster without sleep. We cannot continue to use /proc/uptime as it only has a 10ms resolution. X-Gentoo-Bug: 348416 X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=348416 Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
Diffstat (limited to 'sh')
-rw-r--r--sh/init.sh.Linux.in20
1 files changed, 14 insertions, 6 deletions
diff --git a/sh/init.sh.Linux.in b/sh/init.sh.Linux.in
index ad48585d..9b045570 100644
--- a/sh/init.sh.Linux.in
+++ b/sh/init.sh.Linux.in
@@ -65,19 +65,27 @@ mount_svcdir()
# By default VServer already has /proc mounted, but OpenVZ does not!
# However, some of our users have an old proc image in /proc
# NFC how they managed that, but the end result means we have to test if
-# /proc actually works or not. We to this by comparing uptime to one a second
-# ago
+# /proc actually works or not. We to this by comparing two reads of
+# /proc/self/stat. They will not match, because at least the minor fault count
+# field (field 10) should have changed.
+#
+# We can use any file here that fills the following requirements:
+# - changes between sequential reads
+# - is world-readable (not blocked in hardened kernel)
+# - Is only a single line (ergo entire check is doable with no forks)
mountproc=true
-if [ -e /proc/uptime ]; then
- up="$(cat /proc/uptime)"
- sleep 1
- if [ "$up" = "$(cat /proc/uptime)" ]; then
+f=/proc/self/stat
+if [ -e $f ]; then
+ exec 9<$f ; read a <&9 ; exec 9<&-
+ exec 9<$f ; read b <&9 ; exec 9<&-
+ if [ "$a" = "$b" ]; then
eerror "You have cruft in /proc that should be deleted"
else
einfo "/proc is already mounted, skipping"
mountproc=false
fi
fi
+unset a b f
if $mountproc; then
procfs="proc"