nvmet-fc: use RCU list iterator for assoc_list

The assoc_list is a RCU protected list, thus use the RCU flavor of list
functions.

Let's use this opportunity and refactor this code and move the lookup
into a helper and give it a descriptive name.

Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index 671d096745a5b8d65111e0dad852e20d5e049bf1..fd229f310c931fbfd6c3132185f2b73c135cd633 100644 (file)
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -1114,14 +1114,27 @@ nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc)
        queue_work(nvmet_wq, &assoc->del_work);
 }
 
+static bool
+nvmet_fc_assoc_exits(struct nvmet_fc_tgtport *tgtport, u64 association_id)
+{
+       struct nvmet_fc_tgt_assoc *a;
+
+       list_for_each_entry_rcu(a, &tgtport->assoc_list, a_list) {
+               if (association_id == a->association_id)
+                       return true;
+       }
+
+       return false;
+}
+
 static struct nvmet_fc_tgt_assoc *
 nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hosthandle)
 {
-       struct nvmet_fc_tgt_assoc *assoc, *tmpassoc;
+       struct nvmet_fc_tgt_assoc *assoc;
        unsigned long flags;
+       bool done;
        u64 ran;
        int idx;
-       bool needrandom = true;
 
        if (!tgtport->pe)
                return NULL;
@@ -1145,24 +1158,21 @@ nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hosthandle)
        INIT_WORK(&assoc->del_work, nvmet_fc_delete_assoc_work);
        atomic_set(&assoc->terminating, 0);
 
-       while (needrandom) {
+       done = false;
+       do {
                get_random_bytes(&ran, sizeof(ran) - BYTES_FOR_QID);
                ran = ran << BYTES_FOR_QID_SHIFT;
 
                spin_lock_irqsave(&tgtport->lock, flags);
-               needrandom = false;
-               list_for_each_entry(tmpassoc, &tgtport->assoc_list, a_list) {
-                       if (ran == tmpassoc->association_id) {
-                               needrandom = true;
-                               break;
-                       }
-               }
-               if (!needrandom) {
+               rcu_read_lock();
+               if (!nvmet_fc_assoc_exits(tgtport, ran)) {
                        assoc->association_id = ran;
                        list_add_tail_rcu(&assoc->a_list, &tgtport->assoc_list);
+                       done = true;
                }
+               rcu_read_unlock();
                spin_unlock_irqrestore(&tgtport->lock, flags);
-       }
+       } while (!done);
 
        return assoc;