From: "Jan Beulich" <JBeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH] x86/mmuext: Unify okay/rc error handling in do_mmuext_op()
Date: Tue, 22 Dec 2015 01:57:25 -0700 [thread overview]
Message-ID: <56791E8502000078000C2243@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1450718160-744-1-git-send-email-andrew.cooper3@citrix.com>
>>> On 21.12.15 at 18:16, <andrew.cooper3@citrix.com> wrote:
> c/s 506db90 "x86/HVM: merge HVM and PVH hypercall tables" introduced a path
> whereby 'okay' was used uninitialised, with broke compilation on CentOS 7.
It appeared to be used uninitialized, but wasn't in fact (i.e. the
outcome - the value rc gets set to - didn't depend on the value
due to
if ( unlikely(!okay) && !rc )
rc = -EINVAL;
being equivalent to
if ( !rc && unlikely(!okay) )
rc = -EINVAL;
(no side effects for the expressions on either side of the &&).
I'll re-word accordingly upon committing, to not give the false
impression of there having been other than a cosmetic problem.
> Splitting the error handling like this is fragile and unnecessary. Drop the
> okay variable entirely and just use rc directly, substituting rc = -EINVAL/0
> for okay = 0/1.
>
> In addition, two error messages are updated to print rc, and some stray
> whitespace is dropped.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
next prev parent reply other threads:[~2015-12-22 8:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-21 17:16 [PATCH] x86/mmuext: Unify okay/rc error handling in do_mmuext_op() Andrew Cooper
2015-12-21 17:50 ` Boris Ostrovsky
2015-12-22 9:56 ` Andrew Cooper
2015-12-22 8:57 ` Jan Beulich [this message]
2015-12-22 9:09 ` Andrew Cooper
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