From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Igor Mammedov <imammedo@redhat.com>
Cc: Peng Liang <liangpeng10@huawei.com>,
mst@redhat.com, qemu-devel@nongnu.org, xiexiangyou@huawei.com,
zhang.zhanghailiang@huawei.com
Subject: Re: [PATCH] ACPI: Avoid infinite recursion when dump-vmstate
Date: Fri, 23 Oct 2020 19:54:41 +0100 [thread overview]
Message-ID: <20201023185441.GP3038@work-vm> (raw)
In-Reply-To: <20201023180933.2fe23875@redhat.com>
* Igor Mammedov (imammedo@redhat.com) wrote:
> On Mon, 19 Oct 2020 17:31:56 +0800
> Peng Liang <liangpeng10@huawei.com> wrote:
>
> > There is a field with vmstate_ghes_state as vmsd in vmstate_ghes_state,
> > which will lead to infinite recursion in dump_vmstate_vmsd.
> >
> > Fixes: a08a64627b ("ACPI: Record the Generic Error Status Block address")
> > Reported-by: Euler Robot <euler.robot@huawei.com>
> > Signed-off-by: Peng Liang <liangpeng10@huawei.com>
> > ---
> > hw/acpi/generic_event_device.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/hw/acpi/generic_event_device.c b/hw/acpi/generic_event_device.c
> > index 6df400e1ee16..4b6867300a55 100644
> > --- a/hw/acpi/generic_event_device.c
> > +++ b/hw/acpi/generic_event_device.c
> > @@ -334,8 +334,7 @@ static const VMStateDescription vmstate_ghes_state = {
> > .minimum_version_id = 1,
> > .needed = ghes_needed,
> > .fields = (VMStateField[]) {
> > - VMSTATE_STRUCT(ghes_state, AcpiGedState, 1,
> > - vmstate_ghes_state, AcpiGhesState),
> > + VMSTATE_UINT64(ghes_state.ghes_addr_le, AcpiGedState),
>
> not sure its' ok handle it this way,
>
> see how it is done with another structure:
>
> static const VMStateDescription vmstate_ged_state = {
> .name = "acpi-ged-state",
> .version_id = 1,
> .minimum_version_id = 1,
> .fields = (VMStateField[]) {
> VMSTATE_UINT32(sel, GEDState),
> VMSTATE_END_OF_LIST()
> }
> };
>
> ...
>
> VMSTATE_STRUCT(ged_state, AcpiGedState, 1, vmstate_ged_state, GEDState),
>
> i.e. it looks like we are missing structure definition for AcpiGhesState
>
> CCing David,
> to help with migration magic in case I'm wrong or missed something
Yeh that's confusing :-)
Given a:
VMSTATE_STRUCT(a, B, 1, vmstate_c, C)
We're saying there's a field 'a' in type B, and field 'a'
should be of type C and be serialised using vmstate_c.
That also means that in any vmstate_c, we're expecting it
to be passed a type C generally.
Having said that; you don't need a struct - you can get away
with that VMSTATE_UINT64, there's two problems:
a) That assumes that your ghes always stays that simple.
b) If you wanted to store a Ghes from a number of different
parent structures then you're stuck because your vmstate_ghes_state
is bound to being a strict field of AcpiGedState.
So yes, it's neatest to do it using a VMSD for AcpiGhesState
And congratulations on finding a loop; I don't think we've ever had one
before :-)
Dave
> > VMSTATE_END_OF_LIST()
> > }
> > };
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2020-10-23 18:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 9:31 [PATCH] ACPI: Avoid infinite recursion when dump-vmstate Peng Liang
2020-10-23 16:09 ` Igor Mammedov
2020-10-23 18:54 ` Dr. David Alan Gilbert [this message]
2020-10-23 19:23 ` Igor Mammedov
2020-10-26 9:40 ` Dr. David Alan Gilbert
2020-10-26 6:22 ` Peng Liang
2020-11-11 14:01 ` Dr. David Alan Gilbert
2020-11-11 17:13 ` Igor Mammedov
2020-11-11 17:26 ` Dr. David Alan Gilbert
2020-11-12 1:28 ` Peng Liang
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=20201023185441.GP3038@work-vm \
--to=dgilbert@redhat.com \
--cc=imammedo@redhat.com \
--cc=liangpeng10@huawei.com \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=xiexiangyou@huawei.com \
--cc=zhang.zhanghailiang@huawei.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).