Re: [Patch v3 03/12] net: mana: Handle vport sharing between devices

David Miller
2022-06-13T10:55:42Z

From: longli@linuxonhyperv.com
Date: Sun, 12 Jun 2022 14:14:45 -0700

> +int mana_cfg_vport(struct mana_port_context *apc, u32 protection_dom_id,
> + u32 doorbell_pg_id)
> {
> + /* Ethernet driver and IB driver can't take the port at the same time */
> + refcount_inc(&apc->port_use_count);
> + if (refcount_read(&apc->port_use_count) > 2) {

This is a racy test, the count could change after the test against
'2'. It would be nice if there was a primitive to do the increment
and test atomically, but I fail to see one that matches this scenerio
currently.

Thank you.