From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64BFEC47092 for ; Tue, 1 Jun 2021 17:41:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4A2F9613CE for ; Tue, 1 Jun 2021 17:41:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234622AbhFARnF (ORCPT ); Tue, 1 Jun 2021 13:43:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:33574 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231331AbhFARnC (ORCPT ); Tue, 1 Jun 2021 13:43:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5027761042; Tue, 1 Jun 2021 17:41:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622569280; bh=2IFDrzvsvhbzI9SgMn3XalE8GIMt01IatSD60Qc5Gmo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j0b+3rm95SfAaBVuhPEnN6N/bHDGpbZlvxz2MUhN1Y8tQzui/fmCb3FS0lS+GWJsQ o5SpVaWWiRcwHIMsgnYCMr1uyzecIfP0dNToJXvWZyviw0eAcBG6yr/PHYBXDPw5kI 9paSMIESAuJs6QhCY7lixIZoZCJBJAKF//LiCQaOVIhwqO0K3WzdKCm47f0+Lbenu5 cG1ACuHAogEa7+XnqlGLqgQ4LXIrv3D0Ogud3q1BT/+9UailhDuUfP5vXtYGj8zYOs JgP4t2aIfOSDQ+TPBNX6fOuo9VmG1RaNDA58ch6RfILS4S+yPLhdfRj/fi3cN7BLka Shwv9Yu7a6S2Q== Date: Tue, 1 Jun 2021 18:41:15 +0100 From: Will Deacon To: Daniel Borkmann Cc: Yanfei Xu , ast@kernel.org, zlim.lnx@gmail.com, catalin.marinas@arm.com, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache Message-ID: <20210601174114.GA29130@willie-the-truck> References: <20210601150625.37419-1-yanfei.xu@windriver.com> <20210601150625.37419-2-yanfei.xu@windriver.com> <56cc1e25-25c3-a3da-64e3-8a1c539d685b@iogearbox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56cc1e25-25c3-a3da-64e3-8a1c539d685b@iogearbox.net> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 01, 2021 at 07:20:04PM +0200, Daniel Borkmann wrote: > On 6/1/21 5:06 PM, Yanfei Xu wrote: > > It's no need to trigger IPI for keeping pipeline fresh in bpf case. > > This needs a more concrete explanation/analysis on "why it is safe" to do so > rather than just saying that it is not needed. Agreed. You need to show how the executing thread ends up going through a context synchronizing operation before jumping to the generated code if the IPI here is removed. Will