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 6EE51C433FE for ; Wed, 16 Nov 2022 21:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232408AbiKPVWQ (ORCPT ); Wed, 16 Nov 2022 16:22:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231871AbiKPVWP (ORCPT ); Wed, 16 Nov 2022 16:22:15 -0500 Received: from mail-pf1-f178.google.com (mail-pf1-f178.google.com [209.85.210.178]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 688895D6BB for ; Wed, 16 Nov 2022 13:22:14 -0800 (PST) Received: by mail-pf1-f178.google.com with SMTP id c203so7555625pfc.11 for ; Wed, 16 Nov 2022 13:22:14 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:from:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Jqu1vIvoJDBHXHOfONNUaF/5HcI7xaOYy9kZBnQu6l8=; b=J+9PvesD0WCb2Qn8zGdBGmVPT/7kdFfZikL9cKIPZP0Qb/sHyhYpu6rElrMeDOMDNM MYqs4lysWjz5F+XylMzOn2arrO6mpVlD3h8UcOtMvtWDKVUcOB9AphvMh8Ff7d/MA0Is tGjyT1o/UFmiZ/gGZ1SngJOtNQxnTZLIkw29yVvyl+riqPtX37dAwmQ0VwsbGqX7s3n+ /bhlAAc36a/q/xWgRUF2qB8P3Q0Z07+pzSrYf8+8JMA4ItfscsgvQnDMuBVfjwcozSiC jA98TNS1Cv8FZdDCTkixRAc6b7jCpZSKjPN3ksbW9dxRt5YJlx+H+1tlN6snlRdYFyaN 1YiA== X-Gm-Message-State: ANoB5pm7VHcAv6e9PDdA1frNXwGHhGXSpasO+NC1BvB75+WZYxENQfjE 7DD9jV8XQgzckZgQ0BWXa44= X-Google-Smtp-Source: AA0mqf4yvK523X6L3GkO1qOPDeWEanpSeIW+pSov7OQbWcwjdq/I8AR7FrDcJYCEqQN9V4kVpH1yxg== X-Received: by 2002:a05:6a00:4299:b0:56c:6f58:5937 with SMTP id bx25-20020a056a00429900b0056c6f585937mr25407552pfb.5.1668633733718; Wed, 16 Nov 2022 13:22:13 -0800 (PST) Received: from ?IPV6:2620:15c:211:201:327b:52b7:c177:a972? ([2620:15c:211:201:327b:52b7:c177:a972]) by smtp.gmail.com with ESMTPSA id 132-20020a62188a000000b00571dda13fafsm9236856pfy.163.2022.11.16.13.22.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Nov 2022 13:22:12 -0800 (PST) Message-ID: Date: Wed, 16 Nov 2022 13:22:11 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 From: Bart Van Assche Subject: Re: [PATCH] scsi: alua: Fix alua_rtpg_queue() To: Martin Wilck , "Martin K . Petersen" Cc: linux-scsi@vger.kernel.org, Sachin Sant , Hannes Reinecke References: <20221115224903.2325529-1-bvanassche@acm.org> <0efc9faa6dd519d1d402a08dbedd5cd7ed0de4f5.camel@suse.com> Content-Language: en-US In-Reply-To: <0efc9faa6dd519d1d402a08dbedd5cd7ed0de4f5.camel@suse.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 11/16/22 02:32, Martin Wilck wrote: > On Tue, 2022-11-15 at 14:49 -0800, Bart Van Assche wrote: > diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c > index 610a51538f03..905b49493e01 100644 > --- a/drivers/scsi/device_handler/scsi_dh_alua.c > +++ b/drivers/scsi/device_handler/scsi_dh_alua.c > @@ -372,12 +372,13 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, > if (pg_updated) > list_add_rcu(&h->node, &pg->dh_list); > spin_unlock_irqrestore(&pg->lock, flags); > - > - alua_rtpg_queue(rcu_dereference_protected(h->pg, > - lockdep_is_held(&h->pg_lock)), > - sdev, NULL, true); > spin_unlock(&h->pg_lock); > > + if (kref_get_unless_zero(&pg->kref)) { > + alua_rtpg_queue(pg, sdev, NULL, true); > + kref_put(&pg->kref, release_port_group); > + } > + > if (old_pg) > kref_put(&old_pg->kref, release_port_group); > > @@ -986,11 +987,22 @@ static bool alua_rtpg_queue(struct alua_port_group *pg, > force = true; > } > if (pg->rtpg_sdev == NULL) { > - pg->interval = 0; > - pg->flags |= ALUA_PG_RUN_RTPG; > - kref_get(&pg->kref); > - pg->rtpg_sdev = sdev; > - start_queue = 1; > + struct alua_dh_data *h = sdev->handler_data; > + struct alua_port_group *sdev_pg = NULL; > + > + if (h) { > + rcu_read_lock(); > + sdev_pg = rcu_dereference(h->pg); > + rcu_read_unlock(); > + } > + > + if (pg == sdev_pg) { > + pg->flags |= ALUA_PG_RUN_RTPG; > + pg->interval = 0; > + kref_get(&pg->kref); > + pg->rtpg_sdev = sdev; > + start_queue = 1; > + } > } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) { > pg->flags |= ALUA_PG_RUN_RTPG; > /* Do not queue if the worker is already running */ Although I like the approach of this patch, how about the implementation below? I think the implementation below is a little cleaner but that might be subjective ... Thanks, Bart. diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c index bd4ee294f5c7..d5a7d6ed5c63 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -354,6 +354,8 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, "%s: port group %x rel port %x\n", ALUA_DH_NAME, group_id, rel_port); + kref_get(&pg->kref); + /* Check for existing port group references */ spin_lock(&h->pg_lock); old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); @@ -373,11 +375,11 @@ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, list_add_rcu(&h->node, &pg->dh_list); spin_unlock_irqrestore(&pg->lock, flags); - alua_rtpg_queue(rcu_dereference_protected(h->pg, - lockdep_is_held(&h->pg_lock)), - sdev, NULL, true); spin_unlock(&h->pg_lock); + alua_rtpg_queue(pg, sdev, NULL, true); + kref_put(&pg->kref, release_port_group); + if (old_pg) kref_put(&old_pg->kref, release_port_group); @@ -986,6 +988,9 @@ static bool alua_rtpg_queue(struct alua_port_group *pg, { int start_queue = 0; unsigned long flags; + + might_sleep(); + if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev)) return false; @@ -996,11 +1001,17 @@ static bool alua_rtpg_queue(struct alua_port_group *pg, force = true; } if (pg->rtpg_sdev == NULL) { - pg->interval = 0; - pg->flags |= ALUA_PG_RUN_RTPG; - kref_get(&pg->kref); - pg->rtpg_sdev = sdev; - start_queue = 1; + struct alua_dh_data *h = sdev->handler_data; + + rcu_read_lock(); + if (rcu_dereference(h->pg) == pg) { + pg->interval = 0; + pg->flags |= ALUA_PG_RUN_RTPG; + kref_get(&pg->kref); + pg->rtpg_sdev = sdev; + start_queue = 1; + } + rcu_read_unlock(); } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) { pg->flags |= ALUA_PG_RUN_RTPG; /* Do not queue if the worker is already running */ @@ -1246,8 +1257,8 @@ static void alua_bus_detach(struct scsi_device *sdev) spin_unlock_irq(&pg->lock); kref_put(&pg->kref, release_port_group); } - sdev->handler_data = NULL; synchronize_rcu(); + sdev->handler_data = NULL; kfree(h); }