2024-02-12 10:37:12

by Daniel Wagner

Subject: [PATCH] nvmet-fc: move RCU read lock to nvmet_fc_assoc_exists

The RCU lock is only needed for the lookup loop and not for
list_ad_tail_rcu call. Thus move it down the call chain into
nvmet_fc_assoc_exists.

While at it also fix the name typo of the function.

Signed-off-by: Daniel Wagner <[email protected]>
---
drivers/nvme/target/fc.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
index fd229f310c93..337ee1cb09ae 100644
--- a/drivers/nvme/target/fc.c
+++ b/drivers/nvme/target/fc.c
@@ -1115,16 +1115,21 @@ nvmet_fc_schedule_delete_assoc(struct nvmet_fc_tgt_assoc *assoc)
}

static bool
-nvmet_fc_assoc_exits(struct nvmet_fc_tgtport *tgtport, u64 association_id)
+nvmet_fc_assoc_exists(struct nvmet_fc_tgtport *tgtport, u64 association_id)
{
struct nvmet_fc_tgt_assoc *a;
+ bool found = false;

+ rcu_read_lock();
list_for_each_entry_rcu(a, &tgtport->assoc_list, a_list) {
- if (association_id == a->association_id)
- return true;
+ if (association_id == a->association_id) {
+ found = true;
+ break;
+ }
}
+ rcu_read_unlock();

- return false;
+ return found;
}

static struct nvmet_fc_tgt_assoc *
@@ -1164,13 +1169,11 @@ nvmet_fc_alloc_target_assoc(struct nvmet_fc_tgtport *tgtport, void *hosthandle)
ran = ran << BYTES_FOR_QID_SHIFT;

spin_lock_irqsave(&tgtport->lock, flags);
- rcu_read_lock();
- if (!nvmet_fc_assoc_exits(tgtport, ran)) {
+ if (!nvmet_fc_assoc_exists(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);

--
2.43.0

2024-02-21 13:12:00

by Daniel Wagner

Subject: Re: [PATCH] nvmet-fc: move RCU read lock to nvmet_fc_assoc_exists

On Mon, Feb 12, 2024 at 11:29:40AM +0100, Daniel Wagner wrote:
> The RCU lock is only needed for the lookup loop and not for
> list_ad_tail_rcu call. Thus move it down the call chain into
> nvmet_fc_assoc_exists.
>
> While at it also fix the name typo of the function.
>
> Signed-off-by: Daniel Wagner <[email protected]>

ping