[PATCH 1/2] kdump-lib-initramfs.sh: ignore the failure of echo

[Pingfan Liu]

The kdump-capture.service will fail, if the following conds are meet up.
-1. boot up a VM with the following cmd:
qemu-kvm -name 'avocado-vt-vm1' -sandbox off -machine pc -nodefaults -vga cirrus \
-drive id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=$guest_img \
-device virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04 \
-device virtio-net-pci,mac=9a:4d:4e:4f:50:51,id=id3DveCw,vectors=4,netdev=idgW5YRp,bus=pci.0,addr=05 \
-netdev tap,id=idgW5YRp \
-m 2048 \
-smp 4,maxcpus=4,cores=2,threads=1,sockets=2 \
-cpu 'SandyBridge',+kvm_pv_unhalt \
-vnc :0 \
-rtc base=utc,clock=host,driftfix=slew \
-boot order=cdn,once=c,menu=off,strict=off \
-enable-kvm \
-monitor stdio \
-qmp tcp:localhost:4444,server,nowait
-2. in kernel cmdline with the following options: console=tty0 console=ttyS0,

Because the "-nodefaults" option in qemu cmd excludes the emulation of serial port, the ttyS0 will
have no real backend device. We can observe such issue in 1st kernel by:
echo teststring > /dev/console or
echo teststring > /dev/ttyS0,
It gets the error "-bash: echo: write error: Input/output error".
Such conds cause small issue in 1st kernel, but it is a big problem for kdump-capture and emergency
service.

This patch aims to work aroundthe issue in kdump-capture service:
dump_fs() return value will affect the following code in dracut-kdump.sh
DUMP_RETVAL=$? <---
do_kdump_post $DUMP_RETVAL
if [ $? -ne 0 ]; then
echo "kdump: kdump_post script exited with non-zero status!"
fi

Although kdump-capture saves the vmcore successfully, but it exit 1 and
fall on emergency service.

Signed-off-by: Pingfan Liu <***@redhat.com>
---
kdump-lib-initramfs.sh | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
index 4c0e2e2..2c18c87 100755
--- a/kdump-lib-initramfs.sh
+++ b/kdump-lib-initramfs.sh
@@ -111,6 +111,8 @@ dump_fs()
sync

echo "kdump: saving vmcore complete"
+ # improper kernel cmdline can cause the failure of echo, we can ignore this kind of failure
+ return 0
}

save_vmcore_dmesg_fs() {

[Pingfan Liu]

The invalid console param in cmdline could cause the emergency service's failure with STDIN error,
and the system can not reboot or enter the shell. This patch verify the cmdline and erase the
buggy param.

The invalid param can be reproduce by the following cmds
-1. boot up a VM with the following cmd:
qemu-kvm -name 'avocado-vt-vm1' -sandbox off -machine pc -nodefaults -vga cirrus \
-drive id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=$guest_img \
-device virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04 \
-device virtio-net-pci,mac=9a:4d:4e:4f:50:51,id=id3DveCw,vectors=4,netdev=idgW5YRp,bus=pci.0,addr=05 \
-netdev tap,id=idgW5YRp \
-m 2048 \
-smp 4,maxcpus=4,cores=2,threads=1,sockets=2 \
-cpu 'SandyBridge',+kvm_pv_unhalt \
-vnc :0 \
-rtc base=utc,clock=host,driftfix=slew \
-boot order=cdn,once=c,menu=off,strict=off \
-enable-kvm \
-monitor stdio \
-qmp tcp:localhost:4444,server,nowait
-2. in kernel cmdline with the following options: console=tty0 console=ttyS0,

Because the "-nodefaults" option in qemu cmd excludes the emulation of serial port, the ttyS0 will
have no real backend device.

Signed-off-by: Pingfan Liu <***@redhat.com>
---
kdumpctl | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/kdumpctl b/kdumpctl
index d7f25d9..ee1b8c4 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -176,6 +176,26 @@ is_dump_to_rootfs()
grep "^default[[:space:]]dump_to_rootfs" /etc/kdump.conf >/dev/null
}

+verify_cmdline()
+{
+ condevs=$(echo $1 | tr " " "\n" | grep "console=" | awk -F "=" '{ print $2 }')
+ echo $condevs
+ verified_cmdline=$1
+ for condev in $condevs
+ do
+ echo "test $condev"
+ if [[ $condev =~ /dev/* ]]; then
+ echo "kexec-tools test $condev" > $condev
+ else
+ echo "kexec-tools test $condev" > /dev/$condev
+ fi
+ if [ $? -ne 0 ]; then
+ verified_cmdline=$(echo $verified_cmdline | sed -n "s/console=$condev/ /p")
+ fi
+ done
+ echo $verified_cmdline
+}
+
# This function performs a series of edits on the command line.
# Store the final result in global $KDUMP_COMMANDLINE.
prepare_cmdline()
@@ -211,6 +231,7 @@ prepare_cmdline()
cmdline=`append_cmdline "${cmdline}" disable_cpu_apicid ${id}`
fi

+ cmdline=`verify_cmdline "$cmdline"`
KDUMP_COMMANDLINE=$cmdline

check_kdump_cpus

[Pingfan Liu]

Please ignore these two patch, I send it to the wrong mailing list.
Sorry for the noise.



----- Original Message -----

Sent: Monday, April 17, 2017 2:44:35 PM
Subject: [PATCH 1/2] kdump-lib-initramfs.sh: ignore the failure of echo
The kdump-capture.service will fail, if the following conds are meet up.
qemu-kvm -name 'avocado-vt-vm1' -sandbox off -machine pc -nodefaults
-vga cirrus \
-drive
id=drive_image1,if=none,snapshot=off,aio=native,cache=none,format=qcow2,file=$guest_img
\
-device
virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04
\
-device
virtio-net-pci,mac=9a:4d:4e:4f:50:51,id=id3DveCw,vectors=4,netdev=idgW5YRp,bus=pci.0,addr=05
\
-netdev tap,id=idgW5YRp \
-m 2048 \
-smp 4,maxcpus=4,cores=2,threads=1,sockets=2 \
-cpu 'SandyBridge',+kvm_pv_unhalt \
-vnc :0 \
-rtc base=utc,clock=host,driftfix=slew \
-boot order=cdn,once=c,menu=off,strict=off \
-enable-kvm \
-monitor stdio \
-qmp tcp:localhost:4444,server,nowait
-2. in kernel cmdline with the following options: console=tty0 console=ttyS0,
Because the "-nodefaults" option in qemu cmd excludes the emulation of
serial port, the ttyS0 will
echo teststring > /dev/console or
echo teststring > /dev/ttyS0,
It gets the error "-bash: echo: write error: Input/output error".
Such conds cause small issue in 1st kernel, but it is a big problem for
kdump-capture and emergency
service.
dump_fs() return value will affect the following code in dracut-kdump.sh
DUMP_RETVAL=$? <---
do_kdump_post $DUMP_RETVAL
if [ $? -ne 0 ]; then
echo "kdump: kdump_post script exited with non-zero status!"
fi
Although kdump-capture saves the vmcore successfully, but it exit 1 and
fall on emergency service.
---
kdump-lib-initramfs.sh | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kdump-lib-initramfs.sh b/kdump-lib-initramfs.sh
index 4c0e2e2..2c18c87 100755
--- a/kdump-lib-initramfs.sh
+++ b/kdump-lib-initramfs.sh
@@ -111,6 +111,8 @@ dump_fs()
sync
echo "kdump: saving vmcore complete"
+ # improper kernel cmdline can cause the failure of echo, we can ignore
this kind of failure
+ return 0
}
save_vmcore_dmesg_fs() {
--
2.7.4
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