[PATCH v2 0/3] Use a standalone kdump emergency shell

[Kairui Song]

Currently kdump use some wrapper around dracut emergency service and
emergency shell, this have many problems:

- If dracut-initqueue failed back to emergency mode due to timeout,
    and faiure action is set to dump_to_rootfs, kdump will try start
    initqueue again, lead to double timeout error.
  - Dracut's emergency shell have many builtin actions, like
    perform dracut emergency_action, ask for root password, generate
    rdsosreport etc.

This series remove the emergency wrapper, and use a standalone kdump
emergency shell. Kdump will always perform final_action after kdump
shell, so simplified version works fine.

Update from V1:
  Fix initqueue status detection in patch 1/3, thanks to Coiby.

Kairui Song (3):
  Don's try to restart dracut-initqueue if it's already there
  Remove the kdump error handler isolation wrapper
  Use a customized emergency shell

dracut-kdump-emergency.service     | 25 +++++++++----------
 dracut-kdump-error-handler.service | 33 ------------------------
 dracut-module-setup.sh             |  1 -
 kdump-lib-initramfs.sh             | 40 +++++++++++++++++++++++++-----
 kexec-tools.spec                   |  2 --
 5 files changed, 46 insertions(+), 55 deletions(-)
 delete mode 100644 dracut-kdump-error-handler.service

[PATCH v2 1/3] Don's try to restart dracut-initqueue if it's already there

[Kairui Song]

This reverts commit 7f1f8f229f546818a891400ac7961e485dcd6f3c again.
Previous, kdump's dump_to_rootfs tried to detect if initqueue is
running and don't start it if it's already running or failed.

But dump_to_rootfs will run after systemd isolate to emergency
target, so previous service status are lost, and the detect
is invalid always return false.

But now we can remove the isolate wrapper in following commitsa,
this detection will be valid and helpful again.

Signed-off-by: Kairui Song 
---
 kdump-lib-initramfs.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
index 5cb0223..eb4b07e 100755
--- a/kdump-lib-initramfs.sh
+++ b/kdump-lib-initramfs.sh
@@ -218,8 +218,11 @@ save_opalcore_fs() {
 dump_to_rootfs()
 {

-    dinfo "Trying to bring up rootfs device"
-    systemctl start dracut-initqueue
+    if ! ( systemctl is-active dracut-initqueue || systemctl is-failed dracut-initqueue ) &> /dev/null; then
+        dinfo "Trying to bring up initqueue for rootfs mount"
+        systemctl start dracut-initqueue
+    fi
+
     dinfo "Waiting for rootfs mount, will timeout after 90 seconds"
     systemctl start sysroot.mount

[PATCH v2 2/3] Remove the kdump error handler isolation wrapper

[Kairui Song]

The wrapper is introduced in commit 002337c, according to the commit
message, the only usage of the wrapper is when dracut-initqueue calls
"systemctl start emergency" directly. In that case, emergency
is started, but not in a isolation mode, which means dracut-initqueue
is still running. On the other hand, emergency will call
"systemctl start 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.

In previous commit we added initqueue status detect in dump_to_rootfs,
so now even without the wrapper, it will not hang.

And actually, previously, with the wrapper, emergency might still hang
for like 30s. When dracut called emergency service because initqueue
timed out, dump_to_rootfs will try start initqueue again and timeout
again. Now with the wrapper removed, we can avoid these two kinds of
hangs, bacause without the isolation we can detect initqueue service
status correctly in such case.

Also remove the invalid header comments in service file, the service
is not part of systemd code. And sync the service spec with dracut.

Signed-off-by: Kairui Song 
---
 dracut-kdump-emergency.service     | 25 +++++++++++-----------
 dracut-kdump-error-handler.service | 33 ------------------------------
 dracut-module-setup.sh             |  1 -
 kexec-tools.spec                   |  2 --
 4 files changed, 12 insertions(+), 49 deletions(-)
 delete mode 100644 dracut-kdump-error-handler.service

diff --git a/dracut-kdump-emergency.service b/dracut-kdump-emergency.service
index e023284..f2f6fad 100644
--- a/dracut-kdump-emergency.service
+++ b/dracut-kdump-emergency.service
@@ -1,27 +1,26 @@
-#  This file is part of systemd.
-#
-#  systemd is free software; you can redistribute it and/or modify it
-#  under the terms of the GNU Lesser General Public License as published by
-#  the Free Software Foundation; either version 2.1 of the License, or
-#  (at your option) any later version.
-
-# This service will be placed in kdump initramfs and replace both the systemd
-# emergency service and dracut emergency shell. IOW, any emergency will be
-# kick this service and in turn isolating to kdump error handler.
+# This service will run the real kdump error handler code. Executing the
+# failure action configured in kdump.conf

[Unit]
-Description=Kdump Emergency
+Description=Kdump Error Handler
 DefaultDependencies=no
-IgnoreOnIsolate=yes
+After=systemd-vconsole-setup.service
+Wants=systemd-vconsole-setup.service

[Service]
-ExecStart=/usr/bin/systemctl --no-block isolate kdump-error-handler.service
+Environment=HOME=/
+Environment=DRACUT_SYSTEMD=1
+Environment=NEWROOT=/sysroot
+WorkingDirectory=/
+ExecStart=/bin/kdump-error-handler.sh
+ExecStopPost=-/bin/rm -f -- /.console_lock
 Type=oneshot
 StandardInput=tty-force
 StandardOutput=inherit
 StandardError=inherit
 KillMode=process
 IgnoreSIGPIPE=no
+TasksMax=infinity

# Bash ignores SIGTERM, so we send SIGHUP instead, to ensure that bash
 # terminates cleanly.
diff --git a/dracut-kdump-error-handler.service b/dracut-kdump-error-handler.service
deleted file mode 100644
index a23b75e..0000000
--- a/dracut-kdump-error-handler.service
+++ /dev/null
@@ -1,33 +0,0 @@
-#  This file is part of systemd.
-#
-#  systemd is free software; you can redistribute it and/or modify it
-#  under the terms of the GNU Lesser General Public License as published by
-#  the Free Software Foundation; either version 2.1 of the License, or
-#  (at your option) any later version.
-
-# This service will run the real kdump error handler code. Executing the
-# failure action configured in kdump.conf
-
-[Unit]
-Description=Kdump Error Handler
-DefaultDependencies=no
-After=systemd-vconsole-setup.service
-Wants=systemd-vconsole-setup.service
-AllowIsolate=yes
-
-[Service]
-Environment=HOME=/
-Environment=DRACUT_SYSTEMD=1
-Environment=NEWROOT=/sysroot
-WorkingDirectory=/
-ExecStart=/bin/kdump-error-handler.sh
-Type=oneshot
-StandardInput=tty-force
-StandardOutput=inherit
-StandardError=inherit
-KillMode=process
-IgnoreSIGPIPE=no
-
-# Bash ignores SIGTERM, so we send SIGHUP instead, to ensure that bash
-# terminates cleanly.
-KillSignal=SIGHUP
diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
index 8316589..b4efc46 100755
--- a/dracut-module-setup.sh
+++ b/dracut-module-setup.sh
@@ -857,7 +857,6 @@ install() {
     inst "$moddir/kdump-capture.service" "$systemdsystemunitdir/kdump-capture.service"
     systemctl -q --root "$initdir" add-wants initrd.target kdump-capture.service
     inst "$moddir/kdump-error-handler.sh" "/usr/bin/kdump-error-handler.sh"
-    inst "$moddir/kdump-error-handler.service" "$systemdsystemunitdir/kdump-error-handler.service"
     # Replace existing emergency service and emergency target
     cp "$moddir/kdump-emergency.service" "$initdir/$systemdsystemunitdir/emergency.service"
     cp "$moddir/kdump-emergency.target" "$initdir/$systemdsystemunitdir/emergency.target"
diff --git a/kexec-tools.spec b/kexec-tools.spec
index 24c6b36..0a6d8e6 100644
--- a/kexec-tools.spec
+++ b/kexec-tools.spec
@@ -49,7 +49,6 @@ Source101: dracut-module-setup.sh
 Source102: dracut-monitor_dd_progress
 Source103: dracut-kdump-error-handler.sh
 Source104: dracut-kdump-emergency.service
-Source105: dracut-kdump-error-handler.service
 Source106: dracut-kdump-capture.service
 Source107: dracut-kdump-emergency.target
 Source108: dracut-early-kdump.sh
@@ -226,7 +225,6 @@ cp %{SOURCE101} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpb
 cp %{SOURCE102} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE102}}
 cp %{SOURCE103} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE103}}
 cp %{SOURCE104} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE104}}
-cp %{SOURCE105} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE105}}
 cp %{SOURCE106} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE106}}
 cp %{SOURCE107} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE107}}
 chmod 755 $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE100}}

[PATCH v2 3/3] Use a customized emergency shell

[Kairui Song]

Use a modified and minimized version of emergency shell.
The differences of this kdump shell and dracut emergency shell are:

- Kdump shell won't generate a rdsosreport automatically
  - Customized prompts
  - Never ask root password
  - Won't tangle with dracut's emergency_action. If emergency_action is
    set, dracut emergency shell will perform dracut's emergency_action
    instead of kdump final_action on exit.
  - If rd.shell=no is set, kdump shell will still work, dracut emergency
    shell won't, even if kdump failure_action is set to shell.

Signed-off-by: Kairui Song 
---
 kdump-lib-initramfs.sh | 33 +++++++++++++++++++++++++++++----
 1 file changed, 29 insertions(+), 4 deletions(-)

diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
index eb4b07e..cd2227b 100755
--- a/kdump-lib-initramfs.sh
+++ b/kdump-lib-initramfs.sh
@@ -233,10 +233,35 @@ dump_to_rootfs()

kdump_emergency_shell()
 {
-    echo "PS1="kdump:\${PWD}# "" >/etc/profile
-    ddebug "Switching to dracut emergency..."
-    /bin/dracut-emergency
-    rm -f /etc/profile
+    ddebug "Switching to kdump emergency shell..."
+
+    [ -f /etc/profile ] && . /etc/profile
+    export PS1='kdump:\${PWD}# '
+
+    . /lib/dracut-lib.sh
+    if [ -f /dracut-state.sh ]; then
+        . /dracut-state.sh 2>/dev/null
+    fi
+
+    source_conf /etc/conf.d
+
+    type plymouth >/dev/null 2>&1 && plymouth quit
+
+    source_hook "emergency"
+    while read _tty rest; do
+        (
+        echo
+        echo
+        echo 'Entering kdump emergency mode.'
+        echo 'Type "journalctl" to view system logs.'
+        echo 'Type "rdsosreport" to generate a sosreport, you can then'
+        echo 'save it elsewhere and attach it to a bug report.'
+        echo
+        echo
+        ) > /dev/$_tty
+    done < /proc/consoles
+    sh -i -l
+    /bin/rm -f -- /.console_lock
 }

do_failure_action()

[PATCH v2 3/3] Use a customized emergency shell

[Coiby Xu]

On Wed, Apr 07, 2021 at 03:55:26PM +0800, Kairui Song wrote:
> Use a modified and minimized version of emergency shell.
> The differences of this kdump shell and dracut emergency shell are:
> Kdump shell won't generate a rdsosreport automatically
> Customized prompts
> Never ask root password
> Won't tangle with dracut's emergency_action. If emergency_action is
> set, dracut emergency shell will perform dracut's emergency_action
> instead of kdump final_action on exit.
> If rd.shell=no is set, kdump shell will still work, dracut emergency
> shell won't, even if kdump failure_action is set to shell.
> Signed-off-by: Kairui Song
>
> kdump-lib-initramfs.sh | 33 +++++++++++++++++++++++++++++----
> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
> index eb4b07e..cd2227b 100755
> --- a/kdump-lib-initramfs.sh
> +++ b/kdump-lib-initramfs.sh
> @@ -233,10 +233,35 @@ dump_to_rootfs()
>
> kdump_emergency_shell()
> {
> echo "PS1="kdump:\${PWD}# "" >/etc/profile
> ddebug "Switching to dracut emergency..."
> /bin/dracut-emergency
> rm -f /etc/profile
> ddebug "Switching to kdump emergency shell..."
> [ -f /etc/profile ] && . /etc/profile
> export PS1='kdump:\${PWD}# '

You forgot to fix the unneeded escaping :)
> . /lib/dracut-lib.sh
> if [ -f /dracut-state.sh ]; then
>    . /dracut-state.sh 2>/dev/null
> fi
> source_conf /etc/conf.d
> type plymouth >/dev/null 2>&1 && plymouth quit
> source_hook "emergency"
> while read _tty rest; do
>    (
>    echo
>    echo
>    echo 'Entering kdump emergency mode.'
>    echo 'Type "journalctl" to view system logs.'
>    echo 'Type "rdsosreport" to generate a sosreport, you can then'
>    echo 'save it elsewhere and attach it to a bug report.'
>    echo
>    echo
>    ) > /dev/$_tty
> done < /proc/consoles
> sh -i -l
> /bin/rm -f -- /.console_lock
>
> }
> do_failure_action()
>
> 2.30.2
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[PATCH v2 3/3] Use a customized emergency shell

[Kairui Song]

On Wed, Apr 7, 2021 at 7:34 PM Coiby Xu  wrote:
> On Wed, Apr 07, 2021 at 03:55:26PM +0800, Kairui Song wrote:
> > Use a modified and minimized version of emergency shell.
> > The differences of this kdump shell and dracut emergency shell are:
> > Kdump shell won't generate a rdsosreport automatically
> > Customized prompts
> > Never ask root password
> > Won't tangle with dracut's emergency_action. If emergency_action is
> > set, dracut emergency shell will perform dracut's emergency_action
> > instead of kdump final_action on exit.
> > If rd.shell=no is set, kdump shell will still work, dracut emergency
> > shell won't, even if kdump failure_action is set to shell.
> > Signed-off-by: Kairui Song
> >
> > kdump-lib-initramfs.sh | 33 +++++++++++++++++++++++++++++----
> > 1 file changed, 29 insertions(+), 4 deletions(-)
> >
> > diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
> > index eb4b07e..cd2227b 100755
> > --- a/kdump-lib-initramfs.sh
> > +++ b/kdump-lib-initramfs.sh
> > @@ -233,10 +233,35 @@ dump_to_rootfs()
> >
> > kdump_emergency_shell()
> > {
> > echo "PS1="kdump:\${PWD}# "" >/etc/profile
> > ddebug "Switching to dracut emergency..."
> > /bin/dracut-emergency
> > rm -f /etc/profile
> > ddebug "Switching to kdump emergency shell..."
> > [ -f /etc/profile ] && . /etc/profile
> > export PS1='kdump:\${PWD}# '
>
> You forgot to fix the unneeded escaping :)

Oops, thanks for the info, I'll fix it in V3.