Re: [PATCH rdma-next v2 8/9] IB/cm: Add lock protection when access av/alt_av's port of a cm_id

[Leon Romanovsky <leon@kernel.org>]

On Thu, Apr 22, 2021 at 04:08:14PM -0300, Jason Gunthorpe wrote:
> On Wed, Apr 21, 2021 at 02:40:38PM +0300, Leon Romanovsky wrote:
> > @@ -303,20 +304,37 @@ static struct ib_mad_send_buf *cm_alloc_msg(struct cm_id_private *cm_id_priv)
> >  	struct ib_mad_agent *mad_agent;
> >  	struct ib_mad_send_buf *m;
> >  	struct ib_ah *ah;
> > +	int ret;
> > +
> > +	read_lock(&cm_id_priv->av_rwlock);
> > +	if (!cm_id_priv->av.port) {
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> >  
> >  	mad_agent = cm_id_priv->av.port->mad_agent;
> > +	if (!mad_agent) {
> > +		ret = -EINVAL;
> > +		goto out;
> > +	}
> > +
> >  	ah = rdma_create_ah(mad_agent->qp->pd, &cm_id_priv->av.ah_attr, 0);
> > -	if (IS_ERR(ah))
> > -		return (void *)ah;
> > +	if (IS_ERR(ah)) {
> > +		ret = PTR_ERR(ah);
> > +		goto out;
> > +	}
> >  
> >  	m = ib_create_send_mad(mad_agent, cm_id_priv->id.remote_cm_qpn,
> >  			       cm_id_priv->av.pkey_index,
> >  			       0, IB_MGMT_MAD_HDR, IB_MGMT_MAD_DATA,
> >  			       GFP_ATOMIC,
> >  			       IB_MGMT_BASE_VERSION);
> > +
> > +	read_unlock(&cm_id_priv->av_rwlock);
> >  	if (IS_ERR(m)) {
> >  		rdma_destroy_ah(ah, 0);
> > -		return m;
> > +		ret = PTR_ERR(m);
> > +		goto out;
> >  	}
> >  
> >  	/* Timeout set by caller if response is expected. */
> > @@ -326,6 +344,10 @@ static struct ib_mad_send_buf *cm_alloc_msg(struct cm_id_private *cm_id_priv)
> >  	refcount_inc(&cm_id_priv->refcount);
> >  	m->context[0] = cm_id_priv;
> >  	return m;
> > +
> > +out:
> > +	read_unlock(&cm_id_priv->av_rwlock);
> 
> This flow has read_unlock happening twice on error

Ohh, sorry, I will fix.

Thanks

> 
> Jason