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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BFE9C4332F for ; Wed, 1 Nov 2023 21:23:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344866AbjKAVX2 (ORCPT ); Wed, 1 Nov 2023 17:23:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232719AbjKAVX0 (ORCPT ); Wed, 1 Nov 2023 17:23:26 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1088E121 for ; Wed, 1 Nov 2023 14:22:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698873757; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=j4Q5+IwvvLZciE9qd6dWmjNxBjBLvEzq9VGta2vDxk4=; b=DfPUQ2NcDCxE0extyQGpHKWkgsxsL95Et5Xe2YVJO2CGvdLxAvCi9nb13xFoBEOurLkW6g FkyYY+Kv7k7N/V/vY8EunmqYGb8u2Q3/1dbEsveHseEKcVMbpZDvEWTSeTO/JqZ9fLfitx 0m0Pme8188J1Kqrkw0dMHn6f+mXWRJE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-532-0sCK311YMxGieL5ndhB_xg-1; Wed, 01 Nov 2023 17:22:33 -0400 X-MC-Unique: 0sCK311YMxGieL5ndhB_xg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 55D8C101A529; Wed, 1 Nov 2023 21:22:32 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.9]) by smtp.corp.redhat.com (Postfix) with ESMTP id E7CC91C060BA; Wed, 1 Nov 2023 21:22:30 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20231101204023.GC32034@redhat.com> References: <20231101204023.GC32034@redhat.com> <20231027095842.GA30868@redhat.com> <1952182.1698853516@warthog.procyon.org.uk> <20231101202302.GB32034@redhat.com> To: Oleg Nesterov Cc: dhowells@redhat.com, Marc Dionne , Alexander Viro , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Chuck Lever , linux-afs@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] rxrpc_find_service_conn_rcu: use read_seqbegin() rather than read_seqbegin_or_lock() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1959104.1698873750.1@warthog.procyon.org.uk> Date: Wed, 01 Nov 2023 21:22:30 +0000 Message-ID: <1959105.1698873750@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oleg Nesterov wrote: > Just none of read_seqbegin_or_lock/need_seqretry/done_seqretry > helpers make any sense in this code. I disagree. I think in at least a couple of cases I do want a locked second path - ideally locked shared if seqlock can be made to use an rwlock instead of a spinlock. David