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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 A8A55C2BA19 for ; Wed, 15 Apr 2020 17:46:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 853052084D for ; Wed, 15 Apr 2020 17:46:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="jRq8dn1Z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2411466AbgDORqo (ORCPT ); Wed, 15 Apr 2020 13:46:44 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:39290 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2411463AbgDORql (ORCPT ); Wed, 15 Apr 2020 13:46:41 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586972800; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=32mKiSh5mH/6u+5qEZsD6TGN1ldNSd/bRgNUizrHtCQ=; b=jRq8dn1ZQWz7hDe105CZPfmW1vetL0nHdpikTJC0eKR3DRScVV5YSG5J383iYPNvERsfDq lKb8sPI+IYNMA+/FaMwbf8DZT+6YFc7o66GGSnPjYXaS1GtcljefV9v2aOQucaevG/u7tx Cf5jef8ji2Qxce4xIlHtd3XEK3pTZZk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-401-y1Bc6XuaPZGPjW7ECV34NA-1; Wed, 15 Apr 2020 13:46:36 -0400 X-MC-Unique: y1Bc6XuaPZGPjW7ECV34NA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 29F0E107ACC4; Wed, 15 Apr 2020 17:46:35 +0000 (UTC) Received: from [10.10.115.103] (ovpn-115-103.rdu2.redhat.com [10.10.115.103]) by smtp.corp.redhat.com (Postfix) with ESMTP id 48F22116D7C; Wed, 15 Apr 2020 17:46:34 +0000 (UTC) Subject: Re: [RFC PATCH 2/5] target: add sysfs session helper functions To: Bart Van Assche , jsmart2021@gmail.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, nab@linux-iscsi.org References: <20200414051514.7296-1-mchristi@redhat.com> <20200414051514.7296-3-mchristi@redhat.com> <20ecaf0e-698c-fb9c-26fd-a1f2dc79392e@acm.org> <5E9745DD.2060009@redhat.com> From: Mike Christie Message-ID: <5E974879.5000407@redhat.com> Date: Wed, 15 Apr 2020 12:46:33 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <5E9745DD.2060009@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 04/15/2020 12:35 PM, Mike Christie wrote: > On 04/14/2020 09:30 PM, Bart Van Assche wrote: >> On 2020-04-13 22:15, Mike Christie wrote: >>> @@ -537,8 +538,15 @@ void transport_deregister_session_configfs(struct se_session *se_sess) >>> } >>> EXPORT_SYMBOL(transport_deregister_session_configfs); >>> >>> + >> >> A single blank line is probably sufficient here? >> > > Yes. That was a cut and paste mistake when I was separating the code > into patches. Will fix. > > >>> void transport_free_session(struct se_session *se_sess) >>> { >>> + kobject_put(&se_sess->kobj); >>> +} >>> +EXPORT_SYMBOL(transport_free_session); >>> + >>> +void __target_free_session(struct se_session *se_sess) >>> +{ >>> struct se_node_acl *se_nacl = se_sess->se_node_acl; >>> >>> /* >>> @@ -582,7 +590,6 @@ void transport_free_session(struct se_session *se_sess) >>> percpu_ref_exit(&se_sess->cmd_count); >>> kmem_cache_free(se_sess_cache, se_sess); >>> } >>> -EXPORT_SYMBOL(transport_free_session); >> >> Does this patch defer execution of the code inside >> transport_free_session() from when transport_free_session() is called to >> when the last reference to a session is dropped? Can that have > > Yes. > >> unintended side effects? How about keeping most of the code that occurs > > Yes. For example, we drop the refcount on the ACL in > __target_free_session so that is now not done until the last session > rerfcount is done. I did this because we reference the acl in a sysfs file. > > >> in transport_free_session() in that function and only freeing the memory >> associated with the session if the last reference is dropped? >> > > I tried to minimize it already. > > That is why I have the new session->fabric_free_cb in the next patch. > That way we do not need refcounts on structs like the tpg and can detach > that like normal in > transport_deregister_session/transport_deregister_session_configfs. > Oh yeah, James and Bart, while investigating Bart's comment I noticed there is a bug where in the session->fabric_free_cb the fabric module needs the fabric_sess_ptr but that will already have been cleared in transport_deregister_session. So James, you will hit a bug in there if you try to adapt elx to these patches right now. I will resend with that fixed and Bart's comments handled.