Fixed S6000 abrupt reboot in 201811 (#6923)

Why I did it
The S6000 devices, the cold reboot is abrupt and it is likely to cause issues which will cause the device to land into EFI shell. Hence the platform reboot will happen after graceful unmount of all the filesystems as in S6100.

How I did it
Moved the platform_reboot to platform_reboot_override and hooked it to the systemd shutdown services as in S6100.
Fixed the "/host unmount failed" issue as well in 201811.

How to verify it
Issue "reboot" command to verify if the reboot is happening gracefully.

Author: rkdevi27

device/dell/x86_64-dell_s6000_s1220-r0/platform_reboot

@@ -171,6 +171,11 @@ sudo cp $IMAGE_CONFIGS/rsyslog/rsyslog-config.sh $FILESYSTEM_ROOT/usr/bin/
 sudo cp $IMAGE_CONFIGS/rsyslog/rsyslog.conf.j2 $FILESYSTEM_ROOT_USR_SHARE_SONIC_TEMPLATES/
 sudo cp $IMAGE_CONFIGS/rsyslog/rsyslog.d/* $FILESYSTEM_ROOT/etc/rsyslog.d/
 
+# Copy syslog override files
+sudo mkdir -p $FILESYSTEM_ROOT/etc/systemd/system/syslog.socket.d
+sudo cp $IMAGE_CONFIGS/syslog/override.conf $FILESYSTEM_ROOT/etc/systemd/system/syslog.socket.d/override.conf
+sudo cp $IMAGE_CONFIGS/syslog/host_umount.sh $FILESYSTEM_ROOT/usr/bin/
+
 # Copy logrotate.d configuration files
 sudo cp -f $IMAGE_CONFIGS/logrotate/logrotate.d/* $FILESYSTEM_ROOT/etc/logrotate.d/
 

files/build_templates/sonic_debian_extension.j2

@@ -0,0 +1,31 @@
+#!/bin/bash
+# This script is invoked at the closure of syslog socket during reboot
+# This will stop journal services, unmount /var/log and delete loop device 
+# associated to /host to ensure proper unmount of /host
+
+journal_stop() {
+    systemctl stop systemd-journald.service
+}
+
+delete_loop_device() {
+    umount /var/log
+    if [[ $? -ne 0 ]]
+    then
+        exit 0
+    fi
+    loop_exist=$(losetup -a | grep loop1 | wc -l)
+    if [ $loop_exist -ne 0 ]; then
+        losetup -d /dev/loop1
+    fi
+}
+
+case "$1" in
+    journal_stop|delete_loop_device)
+        $1
+        ;;
+    *)
+        echo "Usage: $0 {journal_stop|delete_loop_device}" >&2
+        exit 1
+        ;;
+esac
+

files/image_config/syslog/host_umount.sh

@@ -0,0 +1,6 @@
+[Unit]
+After=var-log.mount host.mount local-fs.target
+
+[Socket]
+ExecStopPre=/usr/bin/host_umount.sh journal_stop
+ExecStopPost=/usr/bin/host_umount.sh delete_loop_device

files/image_config/syslog/override.conf

@@ -3,4 +3,7 @@ s6000/scripts/reset-qsfp usr/local/bin
 s6000/scripts/set-fan-speed usr/local/bin
 s6000/systemd/platform-modules-s6000.service etc/systemd/system
 common/io_rd_wr.py usr/local/bin
+s6000/scripts/platform_reboot_override usr/share/sonic/device/x86_64-dell_s6000_s1220-r0
+s6000/scripts/platform_update_reboot_cause usr/share/sonic/device/x86_64-dell_s6000_s1220-r0
+s6000/scripts/override.conf /etc/systemd/system/systemd-reboot.service.d
 s6000/modules/sonic_platform-1.0-py2-none-any.whl usr/share/sonic/device/x86_64-dell_s6000_s1220-r0

platform/broadcom/sonic-platform-modules-dell/debian/platform-modules-s6000.install

@@ -0,0 +1,3 @@
+[Service]
+ExecStart=
+ExecStart=/usr/share/sonic/device/x86_64-dell_s6000_s1220-r0/platform_reboot_override

platform/broadcom/sonic-platform-modules-dell/s6000/scripts/override.conf

@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+
+import os
+import struct
+
+PORT_RES = '/dev/port'
+COLD_RESET = 0xE     # Cold Reset
+WARM_RESET = 0x6     # Warm Reset
+RESET_REG = 0xCF9
+
+def io_reg_write(resource, offset, val):
+    fd = os.open(resource, os.O_RDWR)
+    if fd < 0:
+        print('file open failed %s" % resource')
+        return
+    if os.lseek(fd, offset, os.SEEK_SET) != offset:
+        print('lseek failed on %s' % resource)
+        return
+    ret = os.write(fd, struct.pack('B', val))
+    if ret != 1:
+        print('write failed %d' % ret)
+        return
+    os.close(fd)
+
+if __name__ == "__main__":
+    io_reg_write(PORT_RES, RESET_REG, COLD_RESET) 

platform/broadcom/sonic-platform-modules-dell/s6000/scripts/platform_reboot_override

@@ -0,0 +1,25 @@
+#!/usr/bin/env python
+
+import os
+import struct
+
+NVRAM_RES = '/dev/nvram'
+COLD_RESET = 0xE     # Cold Reset
+WARM_RESET = 0x6     # Warm Reset
+
+def io_reg_write(resource, offset, val):
+    fd = os.open(resource, os.O_RDWR)
+    if fd < 0:
+        print('file open failed %s" % resource')
+        return
+    if os.lseek(fd, offset, os.SEEK_SET) != offset:
+        print('lseek failed on %s' % resource)
+        return
+    ret = os.write(fd, struct.pack('B', val))
+    if ret != 1:
+        print('write failed %d' % ret)
+        return
+    os.close(fd)
+
+if __name__ == "__main__":
+    io_reg_write(NVRAM_RES, 0x49, COLD_RESET)