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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C9A26C35FEE for ; Tue, 17 Sep 2024 07:38:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ze84ou6koJikKNhTCzYOgOHdwKXLUpaZjgGTu0EbPxs=; b=BzxPel7tdzBXqH+O3gCLn0BbBS m6y86SXwfumYv8JhodI6IrhcV+zb/UJvCs7wFPcOHvlKPb7lfW3XsjLpU2pP7JJdgWnh+2Ca1dq4G tcbVb0QHlzCHYXiKklSD8OsXUT0pdTSeRCvW8x7LmDzeNwjgASgYThJEoXI1garp8of4L6rad1AVz KqVsiBVe3dcDNFZZTTHmhuqZesClXPFs4T34tkzZr7/jicDblSx8vycKv+QQXs42NlLWbLBXGp0YT ArLTMyOOC2L9TS1JoVXAvhfCRiuMnIGIWdd963JDWTpMuo2+7MGdoh5JdsU+WW5VOLUmktHPpaFp6 zVZK2xsA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1sqSmw-00000005bwA-3SZU; Tue, 17 Sep 2024 07:38:18 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1sqSlr-00000005bqg-1F5e for linux-arm-kernel@lists.infradead.org; Tue, 17 Sep 2024 07:37:12 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id CCB745C061B; Tue, 17 Sep 2024 07:37:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A56FBC4CEC6; Tue, 17 Sep 2024 07:37:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726558630; bh=jpSqmeV4F8zvF9gkT0QL3/l+GMRq3zlBQCNkbcrgjFQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=djEG01Z03mYMCo6cGpoxgBOctC+8R09k+5yhS2FWuRaTQKORUCzKReDXfyVe+ly9L U60FnjgoNpoW5qqYO+q/+fsHhyl27CC2cnM5UK5sfAkAt5ufz1+DgT4O8eSaBNDD2s ryBMQZF6Eur9NS9JbE9XqXJQWt4/ksA0r+Sq7a6kh4VDNjIbV66ZQcEMNOxJZsRyBU ut2P7VOo0atxYVLSlqadbPQ8HAYOWT6e4a9Vb0+CEMB+S0269r8W/qDkl2zhtdgNHj HSbdlpjAta/H/3XEXjzAidptaz3Ci9H2V52zYY8cxDMQg8z0z6Rd1fwZO+arPHIP9Z 0Wf3jJslP3Low== Date: Tue, 17 Sep 2024 08:37:04 +0100 From: Will Deacon To: "Christoph Lameter (Ampere)" Cc: kernel test robot , Christoph Lameter via B4 Relay , Thomas Gleixner , Catalin Marinas , Peter Zijlstra , Ingo Molnar , Waiman Long , Boqun Feng , oe-kbuild-all@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v3] Avoid memory barrier in read_seqcount() through load acquire Message-ID: <20240917073703.GB27290@willie-the-truck> References: <20240912-seq_optimize-v3-1-8ee25e04dffa@gentwo.org> <202409132135.ki3Mp5EA-lkp@intel.com> <766fe92a-13da-f299-0ecf-f8a477d58a79@gentwo.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <766fe92a-13da-f299-0ecf-f8a477d58a79@gentwo.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240917_003711_426396_51FC91F1 X-CRM114-Status: GOOD ( 22.56 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Sep 16, 2024 at 10:52:18AM -0700, Christoph Lameter (Ampere) wrote: > On Fri, 13 Sep 2024, kernel test robot wrote: > > > >> drivers/gpu/drm/i915/gt/intel_tlb.h:21:47: error: macro "seqprop_sequence" requires 2 arguments, but only 1 given > > From 15d86bc9589f16947c5fb0f34d2947eacd48f853 Mon Sep 17 00:00:00 2001 > From: Christoph Lameter > Date: Mon, 16 Sep 2024 10:44:16 -0700 > Subject: [PATCH] Update Intel DRM use of seqprop_sequence > > One of Intels drivers uses seqprop_sequence() for its tlb sequencing. > We added a parameter so that we can use acquire. Its pretty safe to > assume that this will work without acquire. > > Signed-off-by: Christoph Lameter > --- > drivers/gpu/drm/i915/gt/intel_tlb.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.h b/drivers/gpu/drm/i915/gt/intel_tlb.h > index 337327af92ac..81998c4cd4fb 100644 > --- a/drivers/gpu/drm/i915/gt/intel_tlb.h > +++ b/drivers/gpu/drm/i915/gt/intel_tlb.h > @@ -18,7 +18,7 @@ void intel_gt_fini_tlb(struct intel_gt *gt); > > static inline u32 intel_gt_tlb_seqno(const struct intel_gt *gt) > { > - return seqprop_sequence(>->tlb.seqno); > + return seqprop_sequence(>->tlb.seqno, false); > } Yikes, why is the driver using the seqlock internals here? It's a bit of a pity, as a quick grep suggest that this is the _only_ user of 'seqcount_mutex_t', yet it's still having to work around the API. Will