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Subject: RE: [Patch v3 03/12] net: mana: Handle vport sharing between devices
Thread-Topic: [Patch v3 03/12] net: mana: Handle vport sharing between devices
Thread-Index: AQHYfqGCuf9deSlWrUuCitsFXyo7F61NKaoAgAB+zCA=
Date:   Mon, 13 Jun 2022 18:25:43 +0000
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> Subject: Re: [Patch v3 03/12] net: mana: Handle vport sharing between
> devices
>=20
> From: longli@linuxonhyperv.com
> Date: Sun, 12 Jun 2022 14:14:45 -0700
>=20
> > +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) {
>=20
> 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.
>=20
> Thank you.

I'm changing it to mutex.

Thank you,

Long