From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:44082) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzUnG-0004xJ-G7 for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:32:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QzUnF-0005sE-CY for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:32:30 -0400 Received: from thoth.sbs.de ([192.35.17.2]:19773) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QzUnF-0005rx-44 for qemu-devel@nongnu.org; Fri, 02 Sep 2011 10:32:29 -0400 Message-ID: <4E60E8F9.1020708@siemens.com> Date: Fri, 02 Sep 2011 16:32:25 +0200 From: Jan Kiszka MIME-Version: 1.0 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> In-Reply-To: <20110902112818.13bddde0@doriath> Content-Type: text/plain; charset=ISO-8859-1 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: Luiz Capitulino Cc: "kwolf@redhat.com" , "amit.shah@redhat.com" , "aliguori@us.ibm.com" , "qemu-devel@nongnu.org" , "armbru@redhat.com" 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(); } Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux