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From: Markus Armbruster <armbru@redhat.com>
References: <b604df0885958328765a9d481186a5d60a9ab4b1.1504609507.git.mprivozn@redhat.com>
Date: Tue, 05 Sep 2017 13:50:08 +0200
In-Reply-To: <b604df0885958328765a9d481186a5d60a9ab4b1.1504609507.git.mprivozn@redhat.com>
	(Michal Privoznik's message of "Tue, 5 Sep 2017 13:10:31 +0200")
Message-ID: <87shg1tle7.fsf@dusky.pond.sub.org>
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Subject: Re: [Qemu-devel] [PATCH] watchdog: Allow setting action on the fly
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To: Michal Privoznik <mprivozn@redhat.com>
Cc: qemu-devel@nongnu.org

Michal Privoznik <mprivozn@redhat.com> writes:

> Currently, the only time that users can set watchdog action is at
> the start as all we expose is this -watchdog-action command line
> argument. This is suboptimal when users want to plug the device
> later via monitor. Alternatively, they might want to change the
> action for already existing device on the fly.
>
> Inspired by: https://bugzilla.redhat.com/show_bug.cgi?id=1447169
>
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
> ---
>  hw/watchdog/watchdog.c | 9 +++++++++
>  qapi-schema.json       | 9 +++++++++
>  2 files changed, 18 insertions(+)
>
> diff --git a/hw/watchdog/watchdog.c b/hw/watchdog/watchdog.c
> index 0c5c9cde1c..971f05c61a 100644
> --- a/hw/watchdog/watchdog.c
> +++ b/hw/watchdog/watchdog.c
> @@ -29,6 +29,8 @@
>  #include "qapi-event.h"
>  #include "hw/nmi.h"
>  #include "qemu/help_option.h"
> +#include "qmp-commands.h"
> +#include "qapi/qmp/qerror.h"
>  
>  static int watchdog_action = WDT_RESET;
>  static QLIST_HEAD(watchdog_list, WatchdogTimerModel) watchdog_list;
> @@ -147,3 +149,10 @@ void watchdog_perform_action(void)
>          break;
>      }
>  }
> +
> +void qmp_watchdog_set_action(const char *action, Error **errp)
> +{
> +    if (select_watchdog_action(action) == -1) {
> +        error_setg(errp, QERR_INVALID_PARAMETER, action);
> +    }
> +}
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 802ea53d00..be81ffc0bb 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -6539,3 +6539,12 @@
>  # Since 2.9
>  ##
>  { 'command': 'query-vm-generation-id', 'returns': 'GuidInfo' }
> +
> +##
> +# @watchdog-set-action:
> +#
> +# Set watchdog action
> +#
> +# Since 2.11
> +##
> +{ 'command': 'watchdog-set-action', 'data' : {'action': 'str'} }

@action needs to be a QAPI enum.  It'll replace the #defines in
watchdog.  select_watchdog_action() then calls qapi_enum_parse() to map
string to enum, and qmp_watchdog_set_action() to make the actual change.

Questions?