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 11:28:55 +0100 [thread overview]
Message-ID: <20181005102855.vldsq4kolbs2diuy@zion.uk.xensource.com> (raw)
In-Reply-To: <5BB738FA02000078001EEB89@prv1-mh.provo.novell.com>
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.
The code in this patch is trivially correct, but I think the commit
message should be more straightforward.
Wei.
>
> --- a/xen/common/schedule.c
> +++ b/xen/common/schedule.c
> @@ -1014,7 +1014,7 @@ static long do_poll(struct sched_poll *s
> {
> struct vcpu *v = current;
> struct domain *d = v->domain;
> - evtchn_port_t port;
> + evtchn_port_t port = 0;
> long rc;
> unsigned int i;
>
>
>
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next prev parent reply other threads:[~2018-10-05 10:29 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 [this message]
2018-10-05 11:22 ` Jan Beulich
2018-10-05 11:25 ` Wei Liu
2018-10-05 11:43 ` Andrew Cooper
2018-10-05 11:56 ` Jan Beulich
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