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 8F5C1C197A0 for ; Thu, 16 Nov 2023 13:41:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345007AbjKPNl7 (ORCPT ); Thu, 16 Nov 2023 08:41:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231149AbjKPNl5 (ORCPT ); Thu, 16 Nov 2023 08:41:57 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6888A0 for ; Thu, 16 Nov 2023 05:41:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1700142113; 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=IxptJPCrY+QSm5n5VLsWoPBouQFJKh6ohstDe/UHPEk=; b=OW4yNKHA7etCwlWD6+FoM9U6iDT5s3/JyxfX8jPmSCT5/6GBXHOYjthEXM8D14bmLr9JZF DNNHT/b7wrr+/ZBB3TwiaaCLs8vMMsNu5mGDa4QJIwHa0P49fuDTugzyJczcv407d/rPQR yZo1pmr3wt87lL8IiplrPq3tBm3nhm8= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-587-DSrWWSYgNWKVgZrx_9hZYA-1; Thu, 16 Nov 2023 08:41:50 -0500 X-MC-Unique: DSrWWSYgNWKVgZrx_9hZYA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (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 9AF651C06518; Thu, 16 Nov 2023 13:41:49 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9904910EA1; Thu, 16 Nov 2023 13:41:47 +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: <20231116131849.GA27763@redhat.com> References: <20231116131849.GA27763@redhat.com> <20231027095842.GA30868@redhat.com> To: Oleg Nesterov Cc: dhowells@redhat.com, Marc Dionne , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Al Viro , 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: <104931.1700142106.1@warthog.procyon.org.uk> Date: Thu, 16 Nov 2023 13:41:46 +0000 Message-ID: <104932.1700142106@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oleg Nesterov wrote: > So do you agree that > > - the usage of read_seqbegin_or_lock/need_seqretry in > this code makes no sense because read_seqlock_excl() > is not possible Not exactly. I think it should take a lock on the second pass. > - this patch doesn't change the current behaviour but > simplifies the code and makes it more clear That is true. David