linux-kernel - Re: [PATCH] arm/xen: Don't probe xenbus as part of an early initcall

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Date:   Wed, 10 Feb 2021 13:36:17 -0800 (PST)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     "Woodhouse, David" <dwmw@...zon.co.uk>
cc:     "julien@....org" <julien@....org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "boris.ostrovsky@...cle.com" <boris.ostrovsky@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "sstabellini@...nel.org" <sstabellini@...nel.org>,
        "jgross@...e.com" <jgross@...e.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "iwj@...project.org" <iwj@...project.org>,
        "Grall, Julien" <jgrall@...zon.co.uk>
Subject: Re: [PATCH] arm/xen: Don't probe xenbus as part of an early
 initcall

On Wed, 10 Feb 2021, Woodhouse, David wrote:
> On Wed, 2021-02-10 at 17:06 +0000, Julien Grall wrote:
> > From: Julien Grall <jgrall@...zon.com>
> > 
> > After Commit 3499ba8198cad ("xen: Fix event channel callback via
> > INTX/GSI"), xenbus_probe() will be called too early on Arm. This will
> > recent to a guest hang during boot.
> > 
> > If there hang wasn't there, we would have ended up to call
> > xenbus_probe() twice (the second time is in xenbus_probe_initcall()).
> > 
> > We don't need to initialize xenbus_probe() early for Arm guest.
> > Therefore, the call in xen_guest_init() is now removed.
> > 
> > After this change, there is no more external caller for xenbus_probe().
> > So the function is turned to a static one. Interestingly there were two
> > prototypes for it.
> > 
> > Fixes: 3499ba8198cad ("xen: Fix event channel callback via INTX/GSI")
> > Reported-by: Ian Jackson <iwj@...project.org>
> > Signed-off-by: Julien Grall <jgrall@...zon.com>
> 
> Reviewed-by: David Woodhouse <dwmw@...zon.co.uk>
> Cc: stable@...r.kernel.org

Reviewed-by: Stefano Stabellini <sstabellini@...nel.org>