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From: Wei Liu <wei.liu2@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	George Dunlap <George.Dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
	Julien Grall <julien.grall@arm.com>,
	xen-devel <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH] fix uninitialized variable error in do_poll()
Date: Fri, 5 Oct 2018 12:25:08 +0100	[thread overview]
Message-ID: <20181005112508.4xueqrjv7bysjnpi@zion.uk.xensource.com> (raw)
In-Reply-To: <5BB7497502000078001EEC9A@prv1-mh.provo.novell.com>

On Fri, Oct 05, 2018 at 05:22:29AM -0600, Jan Beulich wrote:
> >>> On 05.10.18 at 12:28, <wei.liu2@citrix.com> wrote:
> > On Fri, Oct 05, 2018 at 04:12:10AM -0600, Jan Beulich wrote:
> >> Now that CONFIG_HVM can (and should) be turned off for the shim, gcc 8.2
> >> apparently is no longer sure that "port" is indeed initialized at
> >> 
> >>     if ( sched_poll->nr_ports == 1 )
> >>         v->poll_evtchn = port;
> >> 
> >> It doesn't look to be impossible for the compiler to prove it is not,
> >> but we also can't rely on that to be the case. Add an initializer.
> >> 
> >> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> > 
> > TBH I fail to see how CONFIG_HVM would affect do_poll. Also there is
> > already build test with gcc 8.2 which never discovered the issue you
> > described.
> 
> I can't explain the sudden diagnostic too (without taking apart what
> exactly the compiler does), but the same config (just with HVM=y)
> built fine before. Without any further insight (which I don't think is
> worth the time) I don't see how I could improve the description.

Oh well.

Acked-by: Wei Liu <wei.liu2@citrix.com>


> 
> Jan
> 
> 

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  reply	other threads:[~2018-10-05 11:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-05 10:12 [PATCH] fix uninitialized variable error in do_poll() Jan Beulich
2018-10-05 10:28 ` Wei Liu
2018-10-05 11:22   ` Jan Beulich
2018-10-05 11:25     ` Wei Liu [this message]
2018-10-05 11:43       ` Andrew Cooper
2018-10-05 11:56         ` Jan Beulich

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