From: davem@davemloft.net (David Miller)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] arm64: bpf: add BPF XADD instruction
Date: Wed, 11 Nov 2015 14:01:06 -0500 (EST) [thread overview]
Message-ID: <20151111.140106.1736782849444456527.davem@davemloft.net> (raw)
In-Reply-To: <20151111174401.GO9562@arm.com>
From: Will Deacon <will.deacon@arm.com>
Date: Wed, 11 Nov 2015 17:44:01 +0000
> On Wed, Nov 11, 2015 at 12:35:48PM -0500, David Miller wrote:
>> From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
>> Date: Wed, 11 Nov 2015 09:27:00 -0800
>>
>> > BPF_XADD == atomic_add() in kernel. period.
>> > we are not going to deprecate it or introduce something else.
>>
>> Agreed, it makes no sense to try and tie C99 or whatever atomic
>> semantics to something that is already clearly defined to have
>> exactly kernel atomic_add() semantics.
>
> ... and which is emitted by LLVM when asked to compile __sync_fetch_and_add,
> which has clearly defined (yet conflicting) semantics.
Alexei clearly stated that he knows about this issue and will fully
fix this up in LLVM.
What more do you need to hear from him once he's stated that he is
aware and is working on it? Meanwhile you should make your JIT emit
what is expected, rather than arguing to change the semantics.
Thanks.
next prev parent reply other threads:[~2015-11-11 19:01 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-10 22:41 [PATCH 0/2] arm64: bpf: add BPF_ST and BPF_XADD instructions support Yang Shi
2015-11-10 22:41 ` [PATCH 1/2] arm64: bpf: add 'store immediate' instruction Yang Shi
2015-11-11 2:45 ` Z Lim
2015-11-11 12:12 ` Will Deacon
2015-11-11 12:39 ` Will Deacon
2015-11-12 19:33 ` Shi, Yang
2015-11-13 3:45 ` Z Lim
2015-11-23 19:34 ` Shi, Yang
2015-11-10 22:41 ` [PATCH 2/2] arm64: bpf: add BPF XADD instruction Yang Shi
2015-11-11 0:08 ` Eric Dumazet
2015-11-11 0:26 ` Shi, Yang
2015-11-11 0:42 ` Alexei Starovoitov
2015-11-11 2:52 ` Z Lim
2015-11-11 8:49 ` Arnd Bergmann
2015-11-11 10:24 ` Will Deacon
2015-11-11 10:42 ` Daniel Borkmann
2015-11-11 11:58 ` Will Deacon
2015-11-11 12:21 ` Daniel Borkmann
2015-11-11 12:38 ` Will Deacon
2015-11-11 12:58 ` Peter Zijlstra
2015-11-11 15:52 ` Daniel Borkmann
2015-11-11 16:23 ` Will Deacon
2015-11-11 17:27 ` Alexei Starovoitov
2015-11-11 17:35 ` David Miller
2015-11-11 17:44 ` Will Deacon
2015-11-11 19:01 ` David Miller [this message]
2015-11-11 17:57 ` Peter Zijlstra
2015-11-11 18:11 ` Alexei Starovoitov
2015-11-11 18:31 ` Peter Zijlstra
2015-11-11 18:41 ` Peter Zijlstra
2015-11-11 18:44 ` Peter Zijlstra
2015-11-11 18:54 ` Peter Zijlstra
2015-11-11 19:55 ` Alexei Starovoitov
2015-11-11 22:21 ` Peter Zijlstra
2015-11-11 23:40 ` Alexei Starovoitov
2015-11-12 8:57 ` Peter Zijlstra
2015-11-11 18:50 ` Daniel Borkmann
2015-11-11 19:04 ` David Miller
2015-11-11 19:23 ` Peter Zijlstra
2015-11-11 19:41 ` Daniel Borkmann
2015-11-11 18:46 ` Will Deacon
2015-11-11 19:01 ` David Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151111.140106.1736782849444456527.davem@davemloft.net \
--to=davem@davemloft.net \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).