[PATCH 1/3] Add an exception handle check function

[PATCH 1/3] Add an exception handle check function

[Baoquan He]

In some cases, exception happened, default handling is called. However,
user may not like the handling, want to specify a handler for these
exceptions.

Add an exception handle check function. Call it where exceptions happened,
and specify a extra special handler. If user want the special handler handles
this exception, related cmdline is added.

Then Dracut will check the cmdline, if related cmdline exists, call the
specified handler; if not, call the default handler.

The function can be called like below:
exception_handle_check -h continue_on_fail

Signed-off-by: Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 modules.d/99base/dracut-lib.sh |   40 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
index cc6c7e8..35ed3a3 100755
--- a/modules.d/99base/dracut-lib.sh
+++ b/modules.d/99base/dracut-lib.sh
@@ -938,6 +938,46 @@ emergency_shell()
     [ -e /run/initramfs/.die ] && exit 1
 }
 
+exception_handle_check()
+{
+    local action_wanted
+    if [ "$1" = "-h" ]; then
+        [ $# -le 1 ] && echo "No exception handler specified" && emergency_shell
+        action_wanted=$2; 
+        case "$action_wanted" in
+        continue_on_fail)
+            ;;
+        reboot)
+            ;;
+        emergency_shell)
+            ;;
+        *)
+            echo "Wrong exception handler input: $action_wanted"
+            action_wanted=emergency_shell
+        esac
+    else
+        action_wanted=emergency_shell
+    fi
+
+    case "$action_wanted" in
+    continue_on_fail)
+        action=$(getarg rd.exceptionhandler=)
+        [ -z "$action" -o  "$action" != "continue_on_fail" ]  && emergency_shell
+        ;;
+    emergency_shell)
+        emergency_shell
+        ;;
+    reboot)
+        reboot -f
+        ;;
+    *) #default
+        ##impossible come here
+        ;;
+    esac
+
+    return 0
+}
+
 # Retain the values of these variables but ensure that they are unexported
 # This is a POSIX-compliant equivalent of bash's "export -n"
 export_n()
-- 
1.7.1

[PATCH 2/3] Specify a special handler when initqueue timeout

[Baoquan He]

In kdump, When the dump device was removed, dracut will drop to shell
during second kernel boot. That means kdump isn't even started. But
in this case, if the target isn't presented, we should dump to a rootfs
device as a default action.

Here call exception_handle_check and specify a handler continue_on_fail
which may be wanted by user, like kdump. If kdump add a cmdline like
rd.exceptionhandler=continue_on_fail, then nothoing done and go on. If
no cmdline rd.exceptionhandler=continue_on_fail added, just drop into
shell as before.

Signed-off-by: Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 modules.d/98systemd/dracut-initqueue.sh |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/modules.d/98systemd/dracut-initqueue.sh b/modules.d/98systemd/dracut-initqueue.sh
index e9da432..c10b32f 100755
--- a/modules.d/98systemd/dracut-initqueue.sh
+++ b/modules.d/98systemd/dracut-initqueue.sh
@@ -17,6 +17,7 @@ RDRETRY=${RDRETRY:-30}
 RDRETRY=$(($RDRETRY*2))
 export RDRETRY
 
+failure="no"
 main_loop=0
 export main_loop
 
@@ -61,9 +62,14 @@ while :; do
     fi
 
     main_loop=$(($main_loop+1))
-    [ $main_loop -gt $RDRETRY ] && emergency_shell "Could not boot."
+    [ $main_loop -gt $RDRETRY ] && failure="yes" && break 
 done
 
+if [ "$failure" = "yes" ]; then
+    failure="no"
+    exception_handler_check -h "continue_on_fail" "Could not boot"
+fi
+
 unset job
 unset queuetriggered
 unset main_loop
-- 
1.7.1

[PATCH 3/3] Add a special handler when mount rootfs failed

[Baoquan He]

Dracut will drop into shell in case anything wrong with rootfs mounting,
but for kdump we does not depends on rootfs for non-rootfs dump and
kdump will handle the default fail action based on user configuration
in /etc/kdump.conf.

Here call exception_handle_check and specify a handler continue_on_fail.
If user add a cmdline like rd.exceptionhandler=continue_on_fail, then
go on. If no cmdline rd.exceptionhandler=continue_on_fail added, just
drop into shell as before.

Signed-off-by: Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 modules.d/98systemd/dracut-initqueue.sh |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/modules.d/98systemd/dracut-initqueue.sh b/modules.d/98systemd/dracut-initqueue.sh
index c10b32f..1d8d5a5 100755
--- a/modules.d/98systemd/dracut-initqueue.sh
+++ b/modules.d/98systemd/dracut-initqueue.sh
@@ -102,9 +102,14 @@ while :; do
     done
 
     i=$(($i+1))
-    [ $i -gt 20 ] && emergency_shell "Can't mount root filesystem"
+    [ $i -gt 20 ] && failure='yes' $$ break
 done
 
+if [ "$failure" = "yes" ]; then
+    exception_handle_check -h "continue_on_fail" "Can't mount root filesystem"
+    failure="no"
+fi
+
 {
     echo -n "Mounted root filesystem "
     while read dev mp rest; do [ "$mp" = "$NEWROOT" ] && echo $dev; done < /proc/mounts
-- 
1.7.1

Re: [PATCH 3/3] Add a special handler when mount rootfs failed

[Baoquan]

On 12/21/2012 04:55 PM, Baoquan He wrote:
> Dracut will drop into shell in case anything wrong with rootfs mounting,
> but for kdump we does not depends on rootfs for non-rootfs dump and
> kdump will handle the default fail action based on user configuration
> in /etc/kdump.conf.
>
> Here call exception_handle_check and specify a handler continue_on_fail.
> If user add a cmdline like rd.exceptionhandler=continue_on_fail, then
> go on. If no cmdline rd.exceptionhandler=continue_on_fail added, just
> drop into shell as before.
>
> Signed-off-by: Baoquan He<bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>   modules.d/98systemd/dracut-initqueue.sh |    7 ++++++-
>   1 files changed, 6 insertions(+), 1 deletions(-)
>
> diff --git a/modules.d/98systemd/dracut-initqueue.sh b/modules.d/98systemd/dracut-initqueue.sh
> index c10b32f..1d8d5a5 100755
> --- a/modules.d/98systemd/dracut-initqueue.sh
> +++ b/modules.d/98systemd/dracut-initqueue.sh
> @@ -102,9 +102,14 @@ while :; do
>       done
>
>       i=$(($i+1))
> -    [ $i -gt 20 ]&&  emergency_shell "Can't mount root filesystem"
In below code "$$" should be "&&". I tested this patchset by changing 
mount-loop limitation count to 1.
     +    [ $i -gt 20 ] && failure='yes' && break
> +    [ $i -gt 20 ]&&  failure='yes' $$ break
>   done
>
> +if [ "$failure" = "yes" ]; then
> +    exception_handle_check -h "continue_on_fail" "Can't mount root filesystem"
> +    failure="no"
> +fi
> +
>   {
>       echo -n "Mounted root filesystem "
>       while read dev mp rest; do [ "$mp" = "$NEWROOT" ]&&  echo $dev; done<  /proc/mounts

Re: [PATCH 1/3] Add an exception handle check function

[Baoquan]

Sorry, cc Vivek and Dave.


On 12/21/2012 04:55 PM, Baoquan He wrote:
> In some cases, exception happened, default handling is called. However,
> user may not like the handling, want to specify a handler for these
> exceptions.
>
> Add an exception handle check function. Call it where exceptions happened,
> and specify a extra special handler. If user want the special handler handles
> this exception, related cmdline is added.
>
> Then Dracut will check the cmdline, if related cmdline exists, call the
> specified handler; if not, call the default handler.
>
> The function can be called like below:
> exception_handle_check -h continue_on_fail
>
> Signed-off-by: Baoquan He<bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>   modules.d/99base/dracut-lib.sh |   40 ++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
> index cc6c7e8..35ed3a3 100755
> --- a/modules.d/99base/dracut-lib.sh
> +++ b/modules.d/99base/dracut-lib.sh
> @@ -938,6 +938,46 @@ emergency_shell()
>       [ -e /run/initramfs/.die ]&&  exit 1
>   }
>
> +exception_handle_check()
> +{
> +    local action_wanted
> +    if [ "$1" = "-h" ]; then
> +        [ $# -le 1 ]&&  echo "No exception handler specified"&&  emergency_shell
> +        action_wanted=$2;
> +        case "$action_wanted" in
> +        continue_on_fail)
> +            ;;
> +        reboot)
> +            ;;
> +        emergency_shell)
> +            ;;
> +        *)
> +            echo "Wrong exception handler input: $action_wanted"
> +            action_wanted=emergency_shell
> +        esac
> +    else
> +        action_wanted=emergency_shell
> +    fi
> +
> +    case "$action_wanted" in
> +    continue_on_fail)
> +        action=$(getarg rd.exceptionhandler=)
> +        [ -z "$action" -o  "$action" != "continue_on_fail" ]&&  emergency_shell
> +        ;;
> +    emergency_shell)
> +        emergency_shell
> +        ;;
> +    reboot)
> +        reboot -f
> +        ;;
> +    *) #default
> +        ##impossible come here
> +        ;;
> +    esac
> +
> +    return 0
> +}
> +
>   # Retain the values of these variables but ensure that they are unexported
>   # This is a POSIX-compliant equivalent of bash's "export -n"
>   export_n()

Re: [PATCH 1/3] Add an exception handle check function

[Baoquan]

Hi Harald,

Could you review this patchset and give some suggestion?

Thanks a lot!


On 12/21/2012 04:55 PM, Baoquan He wrote:
> In some cases, exception happened, default handling is called. However,
> user may not like the handling, want to specify a handler for these
> exceptions.
>
> Add an exception handle check function. Call it where exceptions happened,
> and specify a extra special handler. If user want the special handler handles
> this exception, related cmdline is added.
>
> Then Dracut will check the cmdline, if related cmdline exists, call the
> specified handler; if not, call the default handler.
>
> The function can be called like below:
> exception_handle_check -h continue_on_fail
>
> Signed-off-by: Baoquan He<bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>   modules.d/99base/dracut-lib.sh |   40 ++++++++++++++++++++++++++++++++++++++++
>   1 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
> index cc6c7e8..35ed3a3 100755
> --- a/modules.d/99base/dracut-lib.sh
> +++ b/modules.d/99base/dracut-lib.sh
> @@ -938,6 +938,46 @@ emergency_shell()
>       [ -e /run/initramfs/.die ]&&  exit 1
>   }
>
> +exception_handle_check()
> +{
> +    local action_wanted
> +    if [ "$1" = "-h" ]; then
> +        [ $# -le 1 ]&&  echo "No exception handler specified"&&  emergency_shell
> +        action_wanted=$2;
> +        case "$action_wanted" in
> +        continue_on_fail)
> +            ;;
> +        reboot)
> +            ;;
> +        emergency_shell)
> +            ;;
> +        *)
> +            echo "Wrong exception handler input: $action_wanted"
> +            action_wanted=emergency_shell
> +        esac
> +    else
> +        action_wanted=emergency_shell
> +    fi
> +
> +    case "$action_wanted" in
> +    continue_on_fail)
> +        action=$(getarg rd.exceptionhandler=)
> +        [ -z "$action" -o  "$action" != "continue_on_fail" ]&&  emergency_shell
> +        ;;
> +    emergency_shell)
> +        emergency_shell
> +        ;;
> +    reboot)
> +        reboot -f
> +        ;;
> +    *) #default
> +        ##impossible come here
> +        ;;
> +    esac
> +
> +    return 0
> +}
> +
>   # Retain the values of these variables but ensure that they are unexported
>   # This is a POSIX-compliant equivalent of bash's "export -n"
>   export_n()

Re: [PATCH 1/3] Add an exception handle check function

[Dave Young]

On 12/21/2012 04:55 PM, Baoquan He wrote:
> In some cases, exception happened, default handling is called. However,
> user may not like the handling, want to specify a handler for these
> exceptions.
> 
> Add an exception handle check function. Call it where exceptions happened,
> and specify a extra special handler. If user want the special handler handles
> this exception, related cmdline is added.
> 
> Then Dracut will check the cmdline, if related cmdline exists, call the
> specified handler; if not, call the default handler.
> 
> The function can be called like below:
> exception_handle_check -h continue_on_fail

I think exception_handle is not a good name, how about use "failaction"
instead?

And maybe use below action names:
failaction=continue/shell

IMHO, reboot is not useful for usual initrd. For kdump add a "continue"
is enough because kdump module will handle failure of itself as long as
dracut ignore previous failures.

These 3 patches should better to be one patch. Or split them to 2
patches as below
1/2: make emergency_shell as a fail action
2/2: add a new fail action of "continue"

> 
> Signed-off-by: Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> ---
>  modules.d/99base/dracut-lib.sh |   40 ++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 40 insertions(+), 0 deletions(-)
> 
> diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
> index cc6c7e8..35ed3a3 100755
> --- a/modules.d/99base/dracut-lib.sh
> +++ b/modules.d/99base/dracut-lib.sh
> @@ -938,6 +938,46 @@ emergency_shell()
>      [ -e /run/initramfs/.die ] && exit 1
>  }
>  
> +exception_handle_check()
> +{
> +    local action_wanted
> +    if [ "$1" = "-h" ]; then
> +        [ $# -le 1 ] && echo "No exception handler specified" && emergency_shell

Not necessary use "-h", just make shell as the default action.

Add a functions like get_fail_action(), and do_fail_action(), call them
at different points.

> +        action_wanted=$2; 
> +        case "$action_wanted" in
> +        continue_on_fail)
> +            ;;
> +        reboot)
> +            ;;
> +        emergency_shell)
> +            ;;
> +        *)
> +            echo "Wrong exception handler input: $action_wanted"
> +            action_wanted=emergency_shell
> +        esac
> +    else
> +        action_wanted=emergency_shell
> +    fi
> +
> +    case "$action_wanted" in
> +    continue_on_fail)
> +        action=$(getarg rd.exceptionhandler=)
> +        [ -z "$action" -o  "$action" != "continue_on_fail" ]  && emergency_shell
> +        ;;
> +    emergency_shell)
> +        emergency_shell
> +        ;;
> +    reboot)
> +        reboot -f
> +        ;;
> +    *) #default
> +        ##impossible come here
> +        ;;
> +    esac
> +
> +    return 0
> +}
> +
>  # Retain the values of these variables but ensure that they are unexported
>  # This is a POSIX-compliant equivalent of bash's "export -n"
>  export_n()
> 


-- 
Thanks
Dave

Re: [PATCH 1/3] Add an exception handle check function

[Dave Young]

On 01/17/2013 06:03 PM, Dave Young wrote:
> On 12/21/2012 04:55 PM, Baoquan He wrote:
>> In some cases, exception happened, default handling is called. However,
>> user may not like the handling, want to specify a handler for these
>> exceptions.
>>
>> Add an exception handle check function. Call it where exceptions happened,
>> and specify a extra special handler. If user want the special handler handles
>> this exception, related cmdline is added.
>>
>> Then Dracut will check the cmdline, if related cmdline exists, call the
>> specified handler; if not, call the default handler.
>>
>> The function can be called like below:
>> exception_handle_check -h continue_on_fail
> 
> I think exception_handle is not a good name, how about use "failaction"
> instead?
> 
> And maybe use below action names:
> failaction=continue/shell
> 
> IMHO, reboot is not useful for usual initrd. For kdump add a "continue"
> is enough because kdump module will handle failure of itself as long as
> dracut ignore previous failures.
> 
> These 3 patches should better to be one patch. Or split them to 2
> patches as below
> 1/2: make emergency_shell as a fail action
> 2/2: add a new fail action of "continue"
> 
>>
>> Signed-off-by: Baoquan He <bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>  modules.d/99base/dracut-lib.sh |   40 ++++++++++++++++++++++++++++++++++++++++
>>  1 files changed, 40 insertions(+), 0 deletions(-)
>>
>> diff --git a/modules.d/99base/dracut-lib.sh b/modules.d/99base/dracut-lib.sh
>> index cc6c7e8..35ed3a3 100755
>> --- a/modules.d/99base/dracut-lib.sh
>> +++ b/modules.d/99base/dracut-lib.sh
>> @@ -938,6 +938,46 @@ emergency_shell()
>>      [ -e /run/initramfs/.die ] && exit 1
>>  }
>>  
>> +exception_handle_check()
>> +{
>> +    local action_wanted
>> +    if [ "$1" = "-h" ]; then
>> +        [ $# -le 1 ] && echo "No exception handler specified" && emergency_shell
> 
> Not necessary use "-h", just make shell as the default action.
> 
> Add a functions like get_fail_action(), and do_fail_action(), call them
> at different points.
> 
>> +        action_wanted=$2; 
>> +        case "$action_wanted" in
>> +        continue_on_fail)
>> +            ;;
>> +        reboot)
>> +            ;;
>> +        emergency_shell)
>> +            ;;
>> +        *)
>> +            echo "Wrong exception handler input: $action_wanted"
>> +            action_wanted=emergency_shell
>> +        esac
>> +    else
>> +        action_wanted=emergency_shell
>> +    fi
>> +
>> +    case "$action_wanted" in
>> +    continue_on_fail)
>> +        action=$(getarg rd.exceptionhandler=)

Another thing is, doc also need update for the new cmdline param

>> +        [ -z "$action" -o  "$action" != "continue_on_fail" ]  && emergency_shell
>> +        ;;
>> +    emergency_shell)
>> +        emergency_shell
>> +        ;;
>> +    reboot)
>> +        reboot -f
>> +        ;;
>> +    *) #default
>> +        ##impossible come here
>> +        ;;
>> +    esac
>> +
>> +    return 0
>> +}
>> +
>>  # Retain the values of these variables but ensure that they are unexported
>>  # This is a POSIX-compliant equivalent of bash's "export -n"
>>  export_n()
>>
> 
> 


-- 
Thanks
Dave

Re: [PATCH 1/3] Add an exception handle check function

[Baoquan]

On 01/17/2013 06:03 PM, Dave Young wrote:
>> In some cases, exception happened, default handling is called. However,
>> >  user may not like the handling, want to specify a handler for these
>> >  exceptions.
>> >  
>> >  Add an exception handle check function. Call it where exceptions happened,
>> >  and specify a extra special handler. If user want the special handler handles
>> >  this exception, related cmdline is added.
>> >  
>> >  Then Dracut will check the cmdline, if related cmdline exists, call the
>> >  specified handler; if not, call the default handler.
>> >  
>> >  The function can be called like below:
>> >  exception_handle_check -h continue_on_fail
> I think exception_handle is not a good name, how about use "failaction"
> instead?
>
> And maybe use below action names:
> failaction=continue/shell
>
> IMHO, reboot is not useful for usual initrd. For kdump add a "continue"
> is enough because kdump module will handle failure of itself as long as
> dracut ignore previous failures.
>
> These 3 patches should better to be one patch. Or split them to 2
> patches as below
> 1/2: make emergency_shell as a fail action
> 2/2: add a new fail action of "continue"
>
I hesitated to name this function, maybe failaction is a good name.

I thought at least there were 3 options, 'continue_on_fail', 
'emergency_shell'  and 'reboot'. After thinking, maybe 'reboot' is not 
necessary. After all rebooting system may not be wanted by user after a 
fail occurred,.

If only 'continue_on_fail' and 'emergency_shell', things will be easier. 
The only question is all insert point of the failaction will take the 
same action. e.g mount loop for rootfs, inirqueue loop and dump target 
mount loop, if user add the  cmdline:
failaction=continue_on_fail
Then all insert point will do the continue on fail.

Anyway, I will repost based on two options 'continue_on_fail' and 
'emergency_shell'.

Baoquan
Thanks a lot!