qemu-devel.nongnu.org archive mirror
 help / color / mirror / Atom feed
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Juan Quintela <quintela@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	qemu-devel@nongnu.org, patches@linaro.org
Subject: Re: [Qemu-devel] [PATCH] migration: Correctly handle subsections with no 'needed' function
Date: Tue, 7 Aug 2018 14:43:05 +0100	[thread overview]
Message-ID: <20180807134304.GH2556@work-vm> (raw)
In-Reply-To: <87muty2u57.fsf@trasno.org>

* Juan Quintela (quintela@redhat.com) wrote:
> Peter Maydell <peter.maydell@linaro.org> wrote:
> > Currently the vmstate subsection handling code treats a subsection
> > with no 'needed' function pointer as if it were the subsection
> > list terminator, so the subsection is never transferred and nor
> > is any subsection following it in the list.
> >
> > Handle NULL 'needed' function pointers in subsections in the same
> > way that we do for top level VMStateDescription structures:
> > treat the subsection as always being needed.
> >
> > This doesn't change behaviour for the current set of devices
> > in the tree, because all subsections declare a 'needed' function.
> >
> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> > ---
> > NB: last para in the commit message is only true once the
> > "Arm migration fixes for 3.0" patchset has been committed.
> > We could optionally drop some of the "use a dummy needed fn"
> > changes once this is in...
> >
> > I thought I'd sent this out a few days back, but apparently not,
> > since it's not on-list...
> >
> >  migration/vmstate.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/migration/vmstate.c b/migration/vmstate.c
> > index 6b9079bb51e..0bc240a3175 100644
> > --- a/migration/vmstate.c
> > +++ b/migration/vmstate.c
> > @@ -418,7 +418,7 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
> >  static const VMStateDescription *
> >  vmstate_get_subsection(const VMStateDescription **sub, char *idstr)
> >  {
> > -    while (sub && *sub && (*sub)->needed) {
> > +    while (sub && *sub) {
> >          if (strcmp(idstr, (*sub)->name) == 0) {
> >              return *sub;
> >          }
> 
> Ack to this one.  Code supposed that needed was alwasy !=0.  We don't
> really care on the reception side.  Good spotted.
> 
> > @@ -486,8 +486,8 @@ static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
> >      int ret = 0;
> >  
> >      trace_vmstate_subsection_save_top(vmsd->name);
> > -    while (sub && *sub && (*sub)->needed) {
> > -        if ((*sub)->needed(opaque)) {
> > +    while (sub && *sub) {
> > +        if (vmstate_save_needed(*sub, opaque)) {
> >              const VMStateDescription *vmsdsub = *sub;
> >              uint8_t len;
> 
> 
> I am not so sure about this one.  Why are we having a subsection without
> a ->needed function?  I don't know why that it is useful for.  if we
> don't have a needed function, then it is just better to just add that
> "subsection" to the normal section, increase the version number and live
> with that, no?

I think people are probably preferring adding a subsection comparing to 
using the _V macros everywhere.  It's also a lot more robust.

Dave

> Later, Juan.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

  parent reply	other threads:[~2018-08-07 13:43 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07 13:03 [Qemu-devel] [PATCH] migration: Correctly handle subsections with no 'needed' function Peter Maydell
2018-08-07 13:17 ` Juan Quintela
2018-08-07 13:21   ` Peter Maydell
2018-08-07 13:25     ` Peter Maydell
2018-08-07 14:32     ` Juan Quintela
2018-08-07 14:39       ` Peter Maydell
2018-08-07 14:49         ` Juan Quintela
2018-08-07 15:00           ` Peter Maydell
2018-08-07 15:05             ` Juan Quintela
2018-08-07 15:09               ` Peter Maydell
2018-08-07 15:12                 ` Dr. David Alan Gilbert
2018-08-08  7:27                 ` Juan Quintela
2018-08-08 13:47                   ` Peter Maydell
2018-08-07 13:43   ` Dr. David Alan Gilbert [this message]
2018-08-07 13:41 ` Dr. David Alan Gilbert

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180807134304.GH2556@work-vm \
    --to=dgilbert@redhat.com \
    --cc=patches@linaro.org \
    --cc=peter.maydell@linaro.org \
    --cc=qemu-devel@nongnu.org \
    --cc=quintela@redhat.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).