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From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Andrew Cooper <andrew.cooper3@citrix.com>, Wei Liu <wl@xen.org>,
	George Dunlap <george.dunlap@citrix.com>,
	Ian Jackson <iwj@xenproject.org>
Subject: Re: [PATCH 2/2][4.15?] x86: fix build when NR_CPUS == 1
Date: Mon, 1 Mar 2021 15:01:27 +0100	[thread overview]
Message-ID: <YDzzt1CXau8vKCn1@Air-de-Roger> (raw)
In-Reply-To: <1d8d5089-32a9-9c42-5949-8f9cd20f33e0@suse.com>

On Mon, Mar 01, 2021 at 09:31:07AM +0100, Jan Beulich wrote:
> In this case the compiler is recognizing that no valid array indexes
> remain (in x2apic_cluster()'s access to per_cpu(cpu_2_logical_apicid,
> ...)), but oddly enough isn't really consistent about the checking it
> does (see the code comment).

I assume this is because of the underlying per_cpu access to
__per_cpu_offset using cpu as the index, in which case wouldn't it be
better to place the BUG_ON there?

Also I wonder why the accesses the same function does to the per_cpu
area before the modified chunk using this_cpu as index don't also
trigger such warnings.

Thanks, Roger.


  reply	other threads:[~2021-03-01 14:02 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-01  8:27 [PATCH 0/2][4.15?] fix build when NR_CPUS == 1 Jan Beulich
2021-03-01  8:30 ` [PATCH 1/2][4.15?] sched: " Jan Beulich
2021-03-01 15:57   ` Ian Jackson
2021-03-01 17:50     ` Dario Faggioli
2021-03-01  8:31 ` [PATCH 2/2][4.15?] x86: " Jan Beulich
2021-03-01 14:01   ` Roger Pau Monné [this message]
2021-03-01 15:14     ` Jan Beulich
2021-03-01 18:00       ` Roger Pau Monné
2021-03-02  9:59         ` Jan Beulich
2021-03-02 10:57           ` Roger Pau Monné
2021-03-02 11:18             ` Jan Beulich
2021-03-01 16:03   ` Ian Jackson
2021-03-02 10:02     ` Jan Beulich
2021-03-02 12:28       ` Ian Jackson
2021-03-02 13:37         ` Jan Beulich
2021-03-01  8:33 ` [PATCH 0/2][4.15?] " Jan Beulich

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