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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 A579DC432BE for ; Thu, 2 Sep 2021 09:20:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8257F60F11 for ; Thu, 2 Sep 2021 09:20:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245279AbhIBJVI (ORCPT ); Thu, 2 Sep 2021 05:21:08 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:49294 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245168AbhIBJVE (ORCPT ); Thu, 2 Sep 2021 05:21:04 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id DC3B020320; Thu, 2 Sep 2021 09:20:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1630574405; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=mCLKxbu6H+gkdS0vBCZqNAhLeUSXY2O0pR+5uorc2Nw=; b=JGF7G2OHkGr0sf/v0m6TDelhbrvh4KOEC7hFWe5P59cDLhEA1aEklrx1qysiYXZtXBWtBH GhyIRC3MQpEcDddcAUaF0F8n6pe70Up3S6aPDkWFd2JxAFMPNTYzEEkk+GTeuZbVMSfWcB ytcYx87TF6x3qLvIWIjI/NGTizWJJIE= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1630574405; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=mCLKxbu6H+gkdS0vBCZqNAhLeUSXY2O0pR+5uorc2Nw=; b=DguZ15XQXGjXoPokT0nFdDs7FBrn0b7Se0GxWqm0Ui+n3W+t6g6SfpH+Krux6Jhir5xq1X FGTZiVVVgCefKDAg== Received: from adalid.arch.suse.de (adalid.arch.suse.de [10.161.8.13]) by relay2.suse.de (Postfix) with ESMTP id 56DE9A3B8D; Thu, 2 Sep 2021 09:20:00 +0000 (UTC) Received: by adalid.arch.suse.de (Postfix, from userid 17828) id C55C1518DECC; Thu, 2 Sep 2021 11:20:05 +0200 (CEST) From: Daniel Wagner To: linux-nvme@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Daniel Wagner , Hannes Reinecke , Keith Busch Subject: [PATCH v2] nvme: avoid race in shutdown namespace removal Date: Thu, 2 Sep 2021 11:20:02 +0200 Message-Id: <20210902092002.67614-1-dwagner@suse.de> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we remove the siblings entry, we update ns->head->list, hence we can't separate the removal and test for being empty. They have to be in the same critical section to avoid a race. To avoid breaking the refcounting imbalance again, add a list empty check to nvme_find_ns_head. Fixes: 5396fdac56d8 ("nvme: fix refcounting imbalance when all paths are down") Cc: Hannes Reinecke Cc: Keith Busch Signed-off-by: Daniel Wagner --- v2: - added nvme_find_ns_head fix as suggested by hch v1: - https://lore.kernel.org/linux-nvme/20210830093618.97657-1-dwagner@suse.de/ drivers/nvme/host/core.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 4a3a33f5f11c..ac9a61d1d011 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -3524,7 +3524,9 @@ static struct nvme_ns_head *nvme_find_ns_head(struct nvme_subsystem *subsys, lockdep_assert_held(&subsys->lock); list_for_each_entry(h, &subsys->nsheads, entry) { - if (h->ns_id == nsid && nvme_tryget_ns_head(h)) + if (h->ns_id != nsid) + continue; + if (!list_empty(&h->list) && nvme_tryget_ns_head(h)) return h; } @@ -3836,6 +3838,10 @@ static void nvme_ns_remove(struct nvme_ns *ns) mutex_lock(&ns->ctrl->subsys->lock); list_del_rcu(&ns->siblings); + if (list_empty(&ns->head->list)) { + list_del_init(&ns->head->entry); + last_path = true; + } mutex_unlock(&ns->ctrl->subsys->lock); /* guarantee not available in head->list */ @@ -3856,13 +3862,6 @@ static void nvme_ns_remove(struct nvme_ns *ns) list_del_init(&ns->list); up_write(&ns->ctrl->namespaces_rwsem); - /* Synchronize with nvme_init_ns_head() */ - mutex_lock(&ns->head->subsys->lock); - if (list_empty(&ns->head->list)) { - list_del_init(&ns->head->entry); - last_path = true; - } - mutex_unlock(&ns->head->subsys->lock); if (last_path) nvme_mpath_shutdown_disk(ns->head); nvme_put_ns(ns); -- 2.29.2