linux-kernel - Re: [PATCH 01/12] xen/manage: keep track of the on-going suspend mode

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Message-ID: <F3C676AB-F983-4AB7-A105-093C931EBC77@amazon.com>
Date:   Mon, 1 Jun 2020 21:00:17 +0000
From:   "Agarwal, Anchal" <anchalag@...zon.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>, "hpa@...or.com" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "jgross@...e.com" <jgross@...e.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Kamata, Munehisa" <kamatam@...zon.com>,
        "sstabellini@...nel.org" <sstabellini@...nel.org>,
        "konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
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        "axboe@...nel.dk" <axboe@...nel.dk>,
        "davem@...emloft.net" <davem@...emloft.net>,
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        "pavel@....cz" <pavel@....cz>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "Valentin, Eduardo" <eduval@...zon.com>,
        "Singh, Balbir" <sblbir@...zon.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "vkuznets@...hat.com" <vkuznets@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "Agarwal, Anchal" <anchalag@...zon.com>
Subject: Re: [PATCH 01/12] xen/manage: keep track of the on-going suspend mode


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    On 5/19/20 7:24 PM, Anchal Agarwal wrote:
    >
    > +enum suspend_modes {
    > +     NO_SUSPEND = 0,
    > +     XEN_SUSPEND,
    > +     PM_SUSPEND,
    > +     PM_HIBERNATION,
    > +};
    > +
    > +/* Protected by pm_mutex */
    > +static enum suspend_modes suspend_mode = NO_SUSPEND;
    > +
    > +bool xen_suspend_mode_is_xen_suspend(void)
    > +{
    > +     return suspend_mode == XEN_SUSPEND;
    > +}
    > +
    > +bool xen_suspend_mode_is_pm_suspend(void)
    > +{
    > +     return suspend_mode == PM_SUSPEND;
    > +}
    > +
    > +bool xen_suspend_mode_is_pm_hibernation(void)
    > +{
    > +     return suspend_mode == PM_HIBERNATION;
    > +}
    > +


    I don't see these last two used anywhere. Are you, in fact,
    distinguishing between PM suspend and hibernation?

Yes, I am. Unless there is a better way to distinguish at runtime which I haven't figured out yet.
The initial design was to have separate states for separate modes. Currently, PM_HIBERNATION is handled 
by !xen_suspend . However, if any case arises where we need to set the suspend_mode, its available via 
this interface. This is basically to support PM* ops via ACPI path. Since, PM_SUSPEND is not handled by the series
the code piece can be removed and added later. Any comments?


    (I would also probably shorten the name a bit, perhaps
    xen_is_pv/pm_suspend()?)

Sure. Will fix in my next round of post.
    -boris

Thanks,
Anchal