kexec-tools/dracut-kdump.sh
WANG Chao 002337c671 Introduce kdump error handling service
Now upon failure kdump script might not be called at all and it might
not be able to execute default action. It results in a hang.

Because we disable emergency shell and rely on kdump.sh being invoked
through dracut-pre-pivot hook. But it might happen that we never call
into dracut-pre-pivot hook because certain systemd targets could not
reach due to failure in their dependencies. In those cases error
handling code does not run and system hangs. For example:

sysroot-var-crash.mount --> initrd-root-fs.target --> initrd.target \
  --> dracut-pre-pivot.service --> kdump.sh

If /sysroot/var/crash mount fails, initrd-root-fs.target will not be
reached. And then initrd.target will not be reached,
dracut-pre-pivot.service wouldn't run. Finally kdump.sh wouldn't run.

To solve this problem, we need to separate the error handling code from
dracut-pre-pivot hook, and every time when a failure shows up, the
separated code can be called by the emergency service.

By default systemd provides an emergency service which will drop us into
shell every time upon a critical failure. It's very convenient for us to
re-use the framework of systemd emergency, because we don't have to
touch the other parts of systemd. We can use our own script instead of
the default one.

This new scheme will overwrite emergency shell and replace with kdump
error handling code. And this code will do the error handling as needed.
Now, we will not rely on dracut-pre-pivot hook running always. Instead
whenever error happens and it is serious enough that emergency shell
needed to run, now kdump error handler will run.

dracut-emergency is also replaced by kdump error handler and it's
enabled again all the way down. So all the failure (including systemd
and dracut) in 2nd kernel could be captured, and trigger kdump error
handler.

dracut-initqueue is a special case, which calls "systemctl start
emergency" directly, not via "OnFailure=emergency". In case of failure,
emergency is started, but not in a isolation mode, which means
dracut-initqueue is still running. On the other hand, emergency will
call dracut-initqueue again when default action is dump_to_rootfs.
systemd would block on the last dracut-initqueue, waiting for the first
instance to exit, which leaves us hang. It looks like the following:

dracut-initqueue (running)
  --> call dracut-emergency:
    --> dracut-emergency (running)
      --> kdump-error-handler.sh (running)
        --> call dracut-initqueue:
          --> blocking and waiting for the original instance to exit.

To fix this, I'd like to introduce a wrapper emergency service. This
emegency service will replace both the systemd and dracut emergency. And
this service does nothing but to isolate to real kdump error handler
service:

dracut-initqueue (running)
  --> call dracut-emergency:
    --> dracut-emergency isolate to kdump-error-handler.service
      --> dracut-emergency and dracut-initqueue will both be stopped
          and kdump-error-handler.service will run kdump-error-handler.sh.

In a normal failure case, this still works:
foo.service fails
  --> trigger emergency.service
    --> emergency.service isolates to kdump-error-handler.service
      --> kdump-error-handler.service will run kdump-error-handler.sh

Signed-off-by: WANG Chao <chaowang@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Dave Young <dyoung@redhat.com>
2014-08-05 13:13:32 +08:00

209 lines
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#!/bin/sh
# continue here only if we have to save dump.
if [ -f /etc/fadump.initramfs ] && [ ! -f /proc/device-tree/rtas/ibm,kernel-dump ]; then
return
fi
exec &> /dev/console
. /lib/dracut-lib.sh
. /lib/kdump-lib-initramfs.sh
set -o pipefail
DUMP_RETVAL=0
export PATH=$PATH:$KDUMP_SCRIPT_DIR
do_dump()
{
local _ret
eval $DUMP_INSTRUCTION
_ret=$?
if [ $_ret -ne 0 ]; then
echo "kdump: saving vmcore failed"
fi
return $_ret
}
do_kdump_pre()
{
if [ -n "$KDUMP_PRE" ]; then
"$KDUMP_PRE"
fi
}
do_kdump_post()
{
if [ -n "$KDUMP_POST" ]; then
"$KDUMP_POST" "$1"
fi
}
add_dump_code()
{
DUMP_INSTRUCTION=$1
}
dump_raw()
{
local _raw=$1
[ -b "$_raw" ] || return 1
echo "kdump: saving to raw disk $_raw"
if ! $(echo -n $CORE_COLLECTOR|grep -q makedumpfile); then
_src_size=`ls -l /proc/vmcore | cut -d' ' -f5`
_src_size_mb=$(($_src_size / 1048576))
monitor_dd_progress $_src_size_mb &
fi
echo "kdump: saving vmcore"
$CORE_COLLECTOR /proc/vmcore | dd of=$_raw bs=$DD_BLKSIZE >> /tmp/dd_progress_file 2>&1 || return 1
sync
echo "kdump: saving vmcore complete"
return 0
}
dump_ssh()
{
local _opt="-i $1 -o BatchMode=yes -o StrictHostKeyChecking=yes"
local _dir="$KDUMP_PATH/$HOST_IP-$DATEDIR"
local _host=$2
echo "kdump: saving to $_host:$_dir"
cat /var/lib/random-seed > /dev/urandom
ssh -q $_opt $_host mkdir -p $_dir || return 1
save_vmcore_dmesg_ssh ${DMESG_COLLECTOR} ${_dir} "${_opt}" $_host
echo "kdump: saving vmcore"
if [ "${CORE_COLLECTOR%%[[:blank:]]*}" = "scp" ]; then
scp -q $_opt /proc/vmcore "$_host:$_dir/vmcore-incomplete" || return 1
ssh $_opt $_host "mv $_dir/vmcore-incomplete $_dir/vmcore" || return 1
else
$CORE_COLLECTOR /proc/vmcore | ssh $_opt $_host "dd bs=512 of=$_dir/vmcore-incomplete" || return 1
ssh $_opt $_host "mv $_dir/vmcore-incomplete $_dir/vmcore.flat" || return 1
fi
echo "kdump: saving vmcore complete"
return 0
}
save_vmcore_dmesg_ssh() {
local _dmesg_collector=$1
local _path=$2
local _opts="$3"
local _location=$4
echo "kdump: saving vmcore-dmesg.txt"
$_dmesg_collector /proc/vmcore | ssh $_opts $_location "dd of=$_path/vmcore-dmesg-incomplete.txt"
_exitcode=$?
if [ $_exitcode -eq 0 ]; then
ssh -q $_opts $_location mv $_path/vmcore-dmesg-incomplete.txt $_path/vmcore-dmesg.txt
echo "kdump: saving vmcore-dmesg.txt complete"
else
echo "kdump: saving vmcore-dmesg.txt failed"
fi
}
get_host_ip()
{
local _host
if is_nfs_dump_target || is_ssh_dump_target
then
kdumpnic=$(getarg kdumpnic=)
[ -z "$kdumpnic" ] && echo "kdump: failed to get kdumpnic!" && return 1
_host=`ip addr show dev $kdumpnic|grep 'inet '`
[ $? -ne 0 ] && echo "kdump: wrong kdumpnic: $kdumpnic" && return 1
_host="${_host##*inet }"
_host="${_host%%/*}"
[ -z "$_host" ] && echo "kdump: wrong kdumpnic: $kdumpnic" && return 1
HOST_IP=$_host
fi
return 0
}
read_kdump_conf()
{
if [ ! -f "$KDUMP_CONF" ]; then
echo "kdump: $KDUMP_CONF not found"
return
fi
get_kdump_confs
# rescan for add code for dump target
while read config_opt config_val;
do
# remove inline comments after the end of a directive.
config_val=$(strip_comments $config_val)
case "$config_opt" in
ext[234]|xfs|btrfs|minix|nfs)
add_dump_code "dump_fs $config_val"
;;
raw)
add_dump_code "dump_raw $config_val"
;;
ssh)
add_dump_code "dump_ssh $SSH_KEY_LOCATION $config_val"
;;
esac
done < $KDUMP_CONF
}
fence_kdump_notify()
{
if [ -n "$FENCE_KDUMP_NODES" ]; then
$FENCE_KDUMP_SEND $FENCE_KDUMP_ARGS $FENCE_KDUMP_NODES &
fi
}
read_kdump_conf
fence_kdump_notify
if [ -z "$CORE_COLLECTOR" ];then
CORE_COLLECTOR=$DEFAULT_CORE_COLLECTOR
if is_ssh_dump_target || is_raw_dump_target; then
CORE_COLLECTOR="$CORE_COLLECTOR -F"
fi
fi
get_host_ip
if [ $? -ne 0 ]; then
echo "kdump: get_host_ip exited with non-zero status!"
do_default_action
do_final_action
fi
if [ -z "$DUMP_INSTRUCTION" ]; then
add_dump_code "dump_fs $NEWROOT"
fi
do_kdump_pre
if [ $? -ne 0 ]; then
echo "kdump: kdump_pre script exited with non-zero status!"
do_final_action
fi
make_trace_mem "kdump saving vmcore" '1:shortmem' '2+:mem' '3+:slab'
do_dump
DUMP_RETVAL=$?
do_kdump_post $DUMP_RETVAL
if [ $? -ne 0 ]; then
echo "kdump: kdump_post script exited with non-zero status!"
fi
if [ $DUMP_RETVAL -ne 0 ]; then
do_default_action
fi
do_final_action