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kpatch: wait for livepatch transitions, poke stragglers

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When loading a livepatch, wait for the patching transition to complete
within a reasonable timeframe, then poke any stalled tasks with a
signal.  If the transition is still taking too long, reverse the patch
and unload the livepatch.

When re-enabling a livepatch, do the same wait and signaling.  If the
expected time expires, disable the livepatch.

When unloading a livepatch, perform the wait/signaling, but only emit an
error message if the transition exceeds the time limit.

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
This commit is contained in:
Joe Lawrence 2017-11-15 10:44:42 -05:00
parent 3582e10e42
commit 52c12cbad6
1 changed files with 48 additions and 0 deletions
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kpatch/kpatch
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@ -26,6 +26,8 @@
INSTALLDIR=/var/lib/kpatch
SCRIPTDIR="$(readlink -f "$(dirname "$(type -p "$0")")")"
VERSION="0.4.0"
POST_ENABLE_WAIT=5 # seconds
POST_SIGNAL_WAIT=60 # seconds
usage_cmd() {
printf ' %-20s\n %s\n' "$1" "$2" >&2
@ -241,6 +243,36 @@ signal_stalled_processes() {
fi
}
wait_for_patch_transition() {
local module="$1"
local i
in_transition "$module" || return 0
echo "waiting (up to $POST_ENABLE_WAIT seconds) for patch transition to complete..."
for (( i=0; i<POST_ENABLE_WAIT; i++ )); do
if ! in_transition "$module" ; then
echo "transition complete ($i seconds)"
return 0
fi
sleep 1s
done
echo "patch transition has stalled, signaling stalled process(es):"
signal_stalled_processes
echo "waiting (up to $POST_SIGNAL_WAIT seconds) for patch transition to complete..."
for (( i=0; i<POST_SIGNAL_WAIT; i++ )); do
if ! in_transition "$module" ; then
echo "transition complete ($i seconds)"
return 0
fi
sleep 1s
done
return 1
}
load_module () {
local module="$1"
@ -266,6 +298,12 @@ load_module () {
if verify_module_checksum "$module"; then # same checksum
echo "module already loaded, re-enabling"
echo 1 > "${moddir}/enabled" || die "failed to re-enable module $modname"
if ! wait_for_patch_transition "$modname" ; then
echo "module $modname did not complete its transition, disabling..."
echo 0 > "${moddir}/enabled" || die "failed to disable module $modname"
wait_for_patch_transition "$modname"
die "error: failed to re-enable module $modname (transition stalled), patch disabled"
fi
return
else
die "error: cannot re-enable patch module $modname, cannot verify checksum match"
@ -296,6 +334,12 @@ load_module () {
fi
done
if ! wait_for_patch_transition "$modname" ; then
echo "module $modname did not complete its transition, unloading..."
unload_module "$modname"
die "error: failed to load module $modname (transition stalled)"
fi
return 0
}
@ -309,6 +353,10 @@ unload_module () {
echo 0 > "$ENABLED" || die "can't disable $PATCH"
fi
if ! wait_for_patch_transition "$PATCH" ; then
die "error: failed to unload module $PATCH (transition stalled)"
fi
echo "unloading patch module: $PATCH"
# ignore any error here because rmmod can fail if the module used
# KPATCH_FORCE_UNSAFE.