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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 BA447C3A5A8 for ; Wed, 4 Sep 2019 17:01:38 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 90A8A21670 for ; Wed, 4 Sep 2019 17:01:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="LV9uIHiG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90A8A21670 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deltatee.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Subject:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Hb4+qzPjEhi10P+NNbS9NeRTPVdP7jIKGrlDt0W+aSY=; b=LV9uIHiG9tQjCY XNaYSHCw5M29yuRcsmFC9XMfAYpZ1qK9PGM6wNOT3jEvHoDs8FOd3OgZuE6+TMv7JPU4fBdDHWEJH yKUo36T1yzp5+WMNy9RxR4UruIBlqC3mJLaQP4ged84JluaqWXBZuuEcH17X/wisS7dAW9JvV5YlK Ux9mjQKAYNzgJQpTA4An18+YFb4bh1mnnCScpIPwYqlCusa8xZtCJrt/TejxDlBAXqZ8tQpvRQHBG vbKE4u6uU+4/5QNsljlXbUnN4e36MfKpC6nOS1otweHVaSrAAf517wACgIb9ICpG4uJk+X9f4peLh Jw2SSmfUQe2UuEvX9n4w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i5Yf1-00059u-Cx; Wed, 04 Sep 2019 17:01:35 +0000 Received: from ale.deltatee.com ([207.54.116.67]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i5Yey-00052G-BM for linux-nvme@lists.infradead.org; Wed, 04 Sep 2019 17:01:34 +0000 Received: from s0106ac1f6bb1ecac.cg.shawcable.net ([70.73.163.230] helo=[192.168.11.155]) by ale.deltatee.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.89) (envelope-from ) id 1i5Yes-0007q5-5s; Wed, 04 Sep 2019 11:01:27 -0600 To: Keith Busch References: <20190831000139.7662-1-logang@deltatee.com> <20190831152910.GA29439@localhost.localdomain> <33af4d94-9f6d-9baa-01fa-0f75ccee263e@deltatee.com> <20190903164620.GA20847@localhost.localdomain> <20190904060558.GA10849@lst.de> <20190904144426.GB21302@localhost.localdomain> <20190904154215.GA20422@lst.de> <20190904155445.GD21302@localhost.localdomain> <20190904163557.GF21302@localhost.localdomain> From: Logan Gunthorpe Message-ID: Date: Wed, 4 Sep 2019 11:01:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190904163557.GF21302@localhost.localdomain> Content-Language: en-US X-SA-Exim-Connect-IP: 70.73.163.230 X-SA-Exim-Rcpt-To: keith.busch@intel.com, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, sagi@grimberg.me, hare@suse.com, axboe@fb.com, hch@lst.de, kbusch@kernel.org X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH] nvme-core: Fix subsystem instance mismatches X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190904_100132_456508_36F28DA0 X-CRM114-Status: GOOD ( 26.14 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Keith Busch , Hannes Reinecke , Sagi Grimberg , "Martin K . Petersen" , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Jens Axboe , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 2019-09-04 10:35 a.m., Keith Busch wrote: > On Wed, Sep 04, 2019 at 10:07:12AM -0600, Logan Gunthorpe wrote: >> Yes, I agree, we can't solve the mismatch problem in the general case: >> with sequences of hot plug events there will always be a case that >> mismatches. I just think we can do better in the simple common default case. > > This may be something where udev can help us. I might be able to find > some time to look at that, but not today. > >>> Can we just ensure there is never a matching controller then? This >>> patch will accomplish that and simpler than wrapping the instance in a >>> refcount'ed object: >>> >>> http://lists.infradead.org/pipermail/linux-nvme/2019-May/024142.html >> >> I don't really like that idea. It reduces the confusion caused by >> mismatching numbers, but causes the controller to never match the >> namespace, which is also confusing but in a different way. >> >> I like the nvme_instance idea. It's not going to be perfect but it has >> some nice properties: the subsystem will try to match the controller's >> instance whenever possible, but in cases where it doesn't, the instance >> number of the subsystem will never be the same as an existing controller. >> >> I'll see if I can work up a quick patch set and see what people think. > > How about this: we have the subsys copy the controller's instance, > and the nvme_free_ctrl() doesn't release it if its subsys matches? Oh, yes that's simpler than the struct/kref method and looks like it will accomplish the same thing. I did some brief testing with it and it seems to work for me (though I don't have any subsystems with multiple controllers). If you want to make a patch out of it you can add my Reviewed-by: Logan Gunthorpe Thanks! Logan > --- > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c > index 14c0bfb55615..8a8279ece5ee 100644 > --- a/drivers/nvme/host/core.c > +++ b/drivers/nvme/host/core.c > @@ -81,7 +81,6 @@ EXPORT_SYMBOL_GPL(nvme_reset_wq); > struct workqueue_struct *nvme_delete_wq; > EXPORT_SYMBOL_GPL(nvme_delete_wq); > > -static DEFINE_IDA(nvme_subsystems_ida); > static LIST_HEAD(nvme_subsystems); > static DEFINE_MUTEX(nvme_subsystems_lock); > > @@ -2344,7 +2343,8 @@ static void nvme_release_subsystem(struct device *dev) > struct nvme_subsystem *subsys = > container_of(dev, struct nvme_subsystem, dev); > > - ida_simple_remove(&nvme_subsystems_ida, subsys->instance); > + if (subsys->instance >= 0) > + ida_simple_remove(&nvme_instance_ida, subsys->instance); > kfree(subsys); > } > > @@ -2473,12 +2473,8 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) > subsys = kzalloc(sizeof(*subsys), GFP_KERNEL); > if (!subsys) > return -ENOMEM; > - ret = ida_simple_get(&nvme_subsystems_ida, 0, 0, GFP_KERNEL); > - if (ret < 0) { > - kfree(subsys); > - return ret; > - } > - subsys->instance = ret; > + > + subsys->instance = -1; > mutex_init(&subsys->lock); > kref_init(&subsys->ref); > INIT_LIST_HEAD(&subsys->ctrls); > @@ -2497,7 +2493,7 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) > subsys->dev.class = nvme_subsys_class; > subsys->dev.release = nvme_release_subsystem; > subsys->dev.groups = nvme_subsys_attrs_groups; > - dev_set_name(&subsys->dev, "nvme-subsys%d", subsys->instance); > + dev_set_name(&subsys->dev, "nvme-subsys%d", ctrl->instance); > device_initialize(&subsys->dev); > > mutex_lock(&nvme_subsystems_lock); > @@ -2528,6 +2524,8 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id) > goto out_put_subsystem; > } > > + if (!found) > + subsys->instance = ctrl->instance; > ctrl->subsys = subsys; > list_add_tail(&ctrl->subsys_entry, &subsys->ctrls); > mutex_unlock(&nvme_subsystems_lock); > @@ -3803,7 +3801,9 @@ static void nvme_free_ctrl(struct device *dev) > container_of(dev, struct nvme_ctrl, ctrl_device); > struct nvme_subsystem *subsys = ctrl->subsys; > > - ida_simple_remove(&nvme_instance_ida, ctrl->instance); > + if (subsys && ctrl->instance != subsys->instance) > + ida_simple_remove(&nvme_instance_ida, ctrl->instance); > + > kfree(ctrl->effects); > nvme_mpath_uninit(ctrl); > __free_page(ctrl->discard_page); > @@ -4085,7 +4085,6 @@ static int __init nvme_core_init(void) > > static void __exit nvme_core_exit(void) > { > - ida_destroy(&nvme_subsystems_ida); > class_destroy(nvme_subsys_class); > class_destroy(nvme_class); > unregister_chrdev_region(nvme_chr_devt, NVME_MINORS); > -- > _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme