From: Daniel Wagner <dwagner@suse.de> To: linux-nvme@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Daniel Wagner <dwagner@suse.de>, Hannes Reinecke <hare@suse.de>, Keith Busch <kbusch@kernel.org> Subject: [PATCH v2] nvme: avoid race in shutdown namespace removal Date: Thu, 2 Sep 2021 11:20:02 +0200 [thread overview] Message-ID: <20210902092002.67614-1-dwagner@suse.de> (raw) 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 <hare@suse.de> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Daniel Wagner <dwagner@suse.de> --- 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 _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Wagner <dwagner@suse.de> To: linux-nvme@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Daniel Wagner <dwagner@suse.de>, Hannes Reinecke <hare@suse.de>, Keith Busch <kbusch@kernel.org> Subject: [PATCH v2] nvme: avoid race in shutdown namespace removal Date: Thu, 2 Sep 2021 11:20:02 +0200 [thread overview] Message-ID: <20210902092002.67614-1-dwagner@suse.de> (raw) 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 <hare@suse.de> Cc: Keith Busch <kbusch@kernel.org> Signed-off-by: Daniel Wagner <dwagner@suse.de> --- 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
next reply other threads:[~2021-09-02 9:20 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-09-02 9:20 Daniel Wagner [this message] 2021-09-02 9:20 ` [PATCH v2] nvme: avoid race in shutdown namespace removal Daniel Wagner 2021-09-06 8:01 ` Christoph Hellwig 2021-09-06 8:01 ` Christoph Hellwig 2021-09-06 8:40 ` Hannes Reinecke 2021-09-06 8:40 ` Hannes Reinecke 2021-09-09 10:06 ` Hannes Reinecke 2021-09-09 10:06 ` Hannes Reinecke 2021-09-09 14:09 ` Christoph Hellwig 2021-09-09 14:09 ` Christoph Hellwig
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