From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:44373) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzUp9-0005y4-FS for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:34:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QzUp8-00061w-Ao for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:34:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39679) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzUp7-00061o-SQ for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:34:26 -0400 Date: Fri, 2 Sep 2011 11:34:21 -0300 From: Luiz Capitulino Message-ID: <20110902113421.27230357@doriath> In-Reply-To: <4E60E8F9.1020708@siemens.com> References: <1314900738-30164-1-git-send-email-lcapitulino@redhat.com> <1314900738-30164-4-git-send-email-lcapitulino@redhat.com> <4E5FCF61.4040404@siemens.com> <20110901153917.112c5428@doriath> <4E5FF20B.5030504@web.de> <20110902112818.13bddde0@doriath> <4E60E8F9.1020708@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/8] RunState: Add additional states List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: "kwolf@redhat.com" , "amit.shah@redhat.com" , "aliguori@us.ibm.com" , "qemu-devel@nongnu.org" , "armbru@redhat.com" On Fri, 02 Sep 2011 16:32:25 +0200 Jan Kiszka wrote: > On 2011-09-02 16:28, Luiz Capitulino wrote: > > On Thu, 01 Sep 2011 22:58:51 +0200 > > Jan Kiszka wrote: > > > >> On 2011-09-01 20:39, Luiz Capitulino wrote: > >>> On Thu, 01 Sep 2011 20:30:57 +0200 > >>> Jan Kiszka wrote: > >>> > >>>> On 2011-09-01 20:12, Luiz Capitulino wrote: > >>>>> Currently, only vm_start() and vm_stop() change the VM state. > >>>>> That's, the state is only changed when starting or stopping the VM. > >>>>> > >>>>> This commit adds the runstate_set() function, which makes it possible > >>>>> to also do state transitions when the VM is stopped or running. > >>>>> > >>>>> Additional states are also added and the current state is stored. > >>>>> > >>>>> Signed-off-by: Luiz Capitulino > >>>>> --- > >>>>> cpus.c | 1 + > >>>>> migration.c | 8 +++++++- > >>>>> sysemu.h | 10 +++++++++- > >>>>> vl.c | 20 ++++++++++++++++++++ > >>>>> 4 files changed, 37 insertions(+), 2 deletions(-) > >>>>> > >>>> > >>>> ... > >>>> > >>>>> diff --git a/vl.c b/vl.c > >>>>> index f0b56a4..59f71fc 100644 > >>>>> --- a/vl.c > >>>>> +++ b/vl.c > >>>>> @@ -321,6 +321,22 @@ static int default_driver_check(QemuOpts *opts, void *opaque) > >>>>> } > >>>>> > >>>>> /***********************************************************/ > >>>>> +/* QEMU state */ > >>>>> + > >>>>> +static RunState current_run_state = RSTATE_NO_STATE; > >>>>> + > >>>>> +bool runstate_check(RunState state) > >>>>> +{ > >>>>> + return current_run_state == state; > >>>>> +} > >>>>> + > >>>>> +void runstate_set(RunState state) > >>>>> +{ > >>>>> + assert(state < RSTATE_MAX); > >>>>> + current_run_state = state; > >>>> > >>>> I still think this should check for valid state transitions instead of > >>>> blindly accepting what the caller passes in. > >>> > >>> I thought your comment where more like a future enhancement than > >>> a request for change. > >> > >> I think we want this now to document at a central place which > >> transitions are valid and which not. State machines without such checks > >> break sooner or later, subtly. > > > > Ok, I'll do it. > > > > Do you have any suggestion on the preferred way to document it? > > Should I use english or try some ascii art? > > My idea is programmatic: > > void runstate_set(RunState new_state) > { > switch (current_state) { > case X: > /* potential comment on why only X->Y or ... is valid */ > if (new_state == Y || ...) { > break; > } else { > abort(); > } Ah, ok. I was thinking in having some fancy graph as documentation, but let's do the simpler way then.