From 4e2f02bf77dac7b8c841f93ae5a71556d733cb04 Mon Sep 17 00:00:00 2001 From: Leonid Ravich Date: Sun, 3 Jan 2021 20:12:54 +0200 Subject: [PATCH] nvmet-fc: use RCU proctection for assoc_list 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 Reviewed-by: James Smart Signed-off-by: Leonid Ravich Signed-off-by: Christoph Hellwig --- 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 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc, u16 qid, u16 sqsize) { struct nvmet_fc_tgt_queue *queue; - unsigned long flags; int ret; if (qid > NVMET_NR_QUEUES) @@ -829,9 +830,7 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc, 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 @@ nvmet_fc_tgt_queue_free(struct kref *ref) { 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 @@ nvmet_fc_tgt_queue_free(struct kref *ref) destroy_workqueue(queue->work_q); - kfree(queue); + kfree_rcu(queue, rcu); } static void @@ -965,24 +961,23 @@ nvmet_fc_find_target_queue(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 @@ nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hosthandle) } 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 @@ nvmet_fc_target_assoc_free(struct kref *ref) 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 @@ nvmet_fc_target_assoc_free(struct kref *ref) 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 @@ nvmet_fc_delete_target_assoc(struct nvmet_fc_tgt_assoc *assoc) { 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 @@ nvmet_fc_delete_target_assoc(struct nvmet_fc_tgt_assoc *assoc) 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 @@ nvmet_fc_find_target_assoc(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 @@ nvmet_fc_find_target_assoc(struct nvmet_fc_tgtport *tgtport, break; } } - spin_unlock_irqrestore(&tgtport->lock, flags); + rcu_read_unlock(); return ret; } @@ -1473,19 +1470,17 @@ nvmet_fc_tgtport_get(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 @@ nvmet_fc_delete_ctrl(struct nvmet_ctrl *ctrl) 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); -- 2.7.4