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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 1B8F9C433DB for ; Mon, 11 Jan 2021 08:12:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D886B22A85 for ; Mon, 11 Jan 2021 08:12:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727776AbhAKIMa (ORCPT ); Mon, 11 Jan 2021 03:12:30 -0500 Received: from verein.lst.de ([213.95.11.211]:49697 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727741AbhAKIM3 (ORCPT ); Mon, 11 Jan 2021 03:12:29 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id BE95667373; Mon, 11 Jan 2021 09:11:46 +0100 (CET) Date: Mon, 11 Jan 2021 09:11:46 +0100 From: Christoph Hellwig To: leonid.ravich@dell.com Cc: james.smart@broadcom.com, lravich@gmail.com, Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] nvmet-fc: associations list protected by rcu, instead of spinlock_irq where possible. Message-ID: <20210111081146.GA27116@lst.de> References: <20201224110542.22219-1-leonid.ravich@dell.com> <1609697575-103348-1-git-send-email-leonid.ravich@dell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1609697575-103348-1-git-send-email-leonid.ravich@dell.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org James, can you review this patch? On Sun, Jan 03, 2021 at 08:12:53PM +0200, leonid.ravich@dell.com wrote: > From: Leonid Ravich > > searching assoc_list protected by rcu_read_lock if list not changed inline. > and according to the rcu list rules. > > queue array embedded into nvmet_fc_tgt_assoc protected by rcu_read_lock > according to rcu dereference/assign rules. > > queue and assoc object freed after grace period by call_rcu. > > tgtport lock taken for changing assoc_list. > > Reviewed-by: Eldad Zinger > Reviewed-by: Elad Grupi > Signed-off-by: Leonid Ravich > --- > 1) fixed sytle issus > 2) queues array protects by rcu as well > > drivers/nvme/target/fc.c | 81 +++++++++++++++++++++++------------------------- > 1 file changed, 38 insertions(+), 43 deletions(-) > > diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c > index cd4e73a..c14c60b 100644 > --- a/drivers/nvme/target/fc.c > +++ b/drivers/nvme/target/fc.c > @@ -145,6 +145,7 @@ struct nvmet_fc_tgt_queue { > struct list_head avail_defer_list; > struct workqueue_struct *work_q; > struct kref ref; > + struct rcu_head rcu; > struct nvmet_fc_fcp_iod fod[]; /* array of fcp_iods */ > } __aligned(sizeof(unsigned long long)); > > @@ -167,6 +168,7 @@ struct nvmet_fc_tgt_assoc { > struct nvmet_fc_tgt_queue *queues[NVMET_NR_QUEUES + 1]; > struct kref ref; > struct work_struct del_work; > + struct rcu_head rcu; > }; > > > @@ -790,7 +792,6 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > u16 qid, u16 sqsize) > { > struct nvmet_fc_tgt_queue *queue; > - unsigned long flags; > int ret; > > if (qid > NVMET_NR_QUEUES) > @@ -829,9 +830,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > goto out_fail_iodlist; > > WARN_ON(assoc->queues[qid]); > - spin_lock_irqsave(&assoc->tgtport->lock, flags); > - assoc->queues[qid] = queue; > - spin_unlock_irqrestore(&assoc->tgtport->lock, flags); > + rcu_assign_pointer(assoc->queues[qid], queue); > > return queue; > > @@ -851,11 +850,8 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > { > struct nvmet_fc_tgt_queue *queue = > container_of(ref, struct nvmet_fc_tgt_queue, ref); > - unsigned long flags; > > - spin_lock_irqsave(&queue->assoc->tgtport->lock, flags); > - queue->assoc->queues[queue->qid] = NULL; > - spin_unlock_irqrestore(&queue->assoc->tgtport->lock, flags); > + rcu_assign_pointer(queue->assoc->queues[queue->qid], NULL); > > nvmet_fc_destroy_fcp_iodlist(queue->assoc->tgtport, queue); > > @@ -863,7 +859,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > > destroy_workqueue(queue->work_q); > > - kfree(queue); > + kfree_rcu(queue, rcu); > } > > static void > @@ -965,24 +961,23 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > struct nvmet_fc_tgt_queue *queue; > u64 association_id = nvmet_fc_getassociationid(connection_id); > u16 qid = nvmet_fc_getqueueid(connection_id); > - unsigned long flags; > > if (qid > NVMET_NR_QUEUES) > return NULL; > > - spin_lock_irqsave(&tgtport->lock, flags); > - list_for_each_entry(assoc, &tgtport->assoc_list, a_list) { > + rcu_read_lock(); > + list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) { > if (association_id == assoc->association_id) { > - queue = assoc->queues[qid]; > + queue = rcu_dereference(assoc->queues[qid]); > if (queue && > (!atomic_read(&queue->connected) || > !nvmet_fc_tgt_q_get(queue))) > queue = NULL; > - spin_unlock_irqrestore(&tgtport->lock, flags); > + rcu_read_unlock(); > return queue; > } > } > - spin_unlock_irqrestore(&tgtport->lock, flags); > + rcu_read_unlock(); > return NULL; > } > > @@ -1137,7 +1132,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > } > if (!needrandom) { > assoc->association_id = ran; > - list_add_tail(&assoc->a_list, &tgtport->assoc_list); > + list_add_tail_rcu(&assoc->a_list, &tgtport->assoc_list); > } > spin_unlock_irqrestore(&tgtport->lock, flags); > } > @@ -1167,7 +1162,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > > nvmet_fc_free_hostport(assoc->hostport); > spin_lock_irqsave(&tgtport->lock, flags); > - list_del(&assoc->a_list); > + list_del_rcu(&assoc->a_list); > oldls = assoc->rcv_disconn; > spin_unlock_irqrestore(&tgtport->lock, flags); > /* if pending Rcv Disconnect Association LS, send rsp now */ > @@ -1177,7 +1172,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > dev_info(tgtport->dev, > "{%d:%d} Association freed\n", > tgtport->fc_target_port.port_num, assoc->a_id); > - kfree(assoc); > + kfree_rcu(assoc, rcu); > nvmet_fc_tgtport_put(tgtport); > } > > @@ -1198,7 +1193,6 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > { > struct nvmet_fc_tgtport *tgtport = assoc->tgtport; > struct nvmet_fc_tgt_queue *queue; > - unsigned long flags; > int i, terminating; > > terminating = atomic_xchg(&assoc->terminating, 1); > @@ -1207,19 +1201,23 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > if (terminating) > return; > > - spin_lock_irqsave(&tgtport->lock, flags); > + > for (i = NVMET_NR_QUEUES; i >= 0; i--) { > - queue = assoc->queues[i]; > - if (queue) { > - if (!nvmet_fc_tgt_q_get(queue)) > - continue; > - spin_unlock_irqrestore(&tgtport->lock, flags); > - nvmet_fc_delete_target_queue(queue); > - nvmet_fc_tgt_q_put(queue); > - spin_lock_irqsave(&tgtport->lock, flags); > + rcu_read_lock(); > + queue = rcu_dereference(assoc->queues[i]); > + if (!queue) { > + rcu_read_unlock(); > + continue; > + } > + > + if (!nvmet_fc_tgt_q_get(queue)) { > + rcu_read_unlock(); > + continue; > } > + rcu_read_unlock(); > + nvmet_fc_delete_target_queue(queue); > + nvmet_fc_tgt_q_put(queue); > } > - spin_unlock_irqrestore(&tgtport->lock, flags); > > dev_info(tgtport->dev, > "{%d:%d} Association deleted\n", > @@ -1234,10 +1232,9 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > { > struct nvmet_fc_tgt_assoc *assoc; > struct nvmet_fc_tgt_assoc *ret = NULL; > - unsigned long flags; > > - spin_lock_irqsave(&tgtport->lock, flags); > - list_for_each_entry(assoc, &tgtport->assoc_list, a_list) { > + rcu_read_lock(); > + list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) { > if (association_id == assoc->association_id) { > ret = assoc; > if (!nvmet_fc_tgt_a_get(assoc)) > @@ -1245,7 +1242,7 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > break; > } > } > - spin_unlock_irqrestore(&tgtport->lock, flags); > + rcu_read_unlock(); > > return ret; > } > @@ -1473,19 +1470,17 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > static void > __nvmet_fc_free_assocs(struct nvmet_fc_tgtport *tgtport) > { > - struct nvmet_fc_tgt_assoc *assoc, *next; > - unsigned long flags; > + struct nvmet_fc_tgt_assoc *assoc; > > - spin_lock_irqsave(&tgtport->lock, flags); > - list_for_each_entry_safe(assoc, next, > - &tgtport->assoc_list, a_list) { > + rcu_read_lock(); > + list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) { > if (!nvmet_fc_tgt_a_get(assoc)) > continue; > if (!schedule_work(&assoc->del_work)) > /* already deleting - release local reference */ > nvmet_fc_tgt_a_put(assoc); > } > - spin_unlock_irqrestore(&tgtport->lock, flags); > + rcu_read_unlock(); > } > > /** > @@ -1568,16 +1563,16 @@ static void nvmet_fc_xmt_ls_rsp(struct nvmet_fc_tgtport *tgtport, > continue; > spin_unlock_irqrestore(&nvmet_fc_tgtlock, flags); > > - spin_lock_irqsave(&tgtport->lock, flags); > - list_for_each_entry(assoc, &tgtport->assoc_list, a_list) { > - queue = assoc->queues[0]; > + rcu_read_lock(); > + list_for_each_entry_rcu(assoc, &tgtport->assoc_list, a_list) { > + queue = rcu_dereference(assoc->queues[0]); > if (queue && queue->nvme_sq.ctrl == ctrl) { > if (nvmet_fc_tgt_a_get(assoc)) > found_ctrl = true; > break; > } > } > - spin_unlock_irqrestore(&tgtport->lock, flags); > + rcu_read_unlock(); > > nvmet_fc_tgtport_put(tgtport); > > -- > 1.9.3 ---end quoted text---