netdev - Re: [oss-drivers] Re: [PATCH net-next v2 7/9] nfp: add metadata to each flow offload

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Date:   Thu, 29 Jun 2017 10:14:29 +0200
From:   Simon Horman <simon.horman@...ronome.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
        oss-drivers@...ronome.com,
        Pieter Jansen van Vuuren 
        <pieter.jansenvanvuuren@...ronome.com>
Subject: Re: [oss-drivers] Re: [PATCH net-next v2 7/9] nfp: add metadata to
 each flow offload

On Wed, Jun 28, 2017 at 07:33:02PM -0700, Jakub Kicinski wrote:
> On Wed, 28 Jun 2017 22:30:00 +0200, Simon Horman wrote:
> > From: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@...ronome.com>
> > 
> > Adds metadata describing the mask id of each flow and keeps track of
> > flows installed in hardware. Previously a flow could not be removed
> > from hardware as there was no way of knowing if that a specific flow
> > was installed. This is solved by storing the offloaded flows in a
> > hash table.
> > 
> > Signed-off-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@...ronome.com>
> > Signed-off-by: Simon Horman <simon.horman@...ronome.com>
> 
> > diff --git a/drivers/net/ethernet/netronome/nfp/flower/main.c b/drivers/net/ethernet/netronome/nfp/flower/main.c
> > index 19f20f819e2f..1103d23a8ec7 100644
> > --- a/drivers/net/ethernet/netronome/nfp/flower/main.c
> > +++ b/drivers/net/ethernet/netronome/nfp/flower/main.c
> > @@ -50,14 +50,6 @@
> >  
> >  #define NFP_FLOWER_ALLOWED_VER 0x0001000000010000UL
> >  
> > -/**
> > - * struct nfp_flower_priv - Flower APP per-vNIC priv data
> > - * @nn:		     Pointer to vNIC
> > - */
> > -struct nfp_flower_priv {
> > -	struct nfp_net *nn;
> > -};
> > -
> >  static const char *nfp_flower_extra_cap(struct nfp_app *app, struct nfp_net *nn)
> >  {
> >  	return "FLOWER";
> > @@ -351,6 +343,12 @@ static int nfp_flower_init(struct nfp_app *app)
> >  	if (!app->priv)
> >  		return -ENOMEM;
> >  
> > +	err = nfp_flower_metadata_init(app);
> > +	if (nfp_flower_metadata_init(app)) {
> 
> You're calling init twice here.  Also please do the error path with
> goto, as explained in review of patch 8 having a proper unwind makes
> later patches easier to review.

Sorry, that was a brain-o on my part. Will fix that and add proper unwind
as you suggest.

> 
> > +		kfree(app->priv);
> > +		return err;
> > +	}
> > +
> >  	return 0;
> >  }
> >  
> 
> > +static int nfp_mask_alloc(struct nfp_app *app, u8 *mask_id)
> > +{
> > +	struct nfp_flower_priv *priv = app->priv;
> > +	struct timespec64 delta, now;
> > +	struct circ_buf *ring;
> > +	u8 temp_id, freed_id;
> > +
> > +	ring = &priv->mask_ids.mask_id_free_list;
> > +	freed_id = NFP_FLOWER_MASK_ENTRY_RS - 1;
> > +	/* Checking for unallocated entries first. */
> > +	if (priv->mask_ids.init_unallocated > 0) {
> > +		*mask_id = priv->mask_ids.init_unallocated;
> > +		priv->mask_ids.init_unallocated--;
> > +		return 0;
> > +	}
> > +
> > +	/* Checking if buffer is empty. */
> > +	if (ring->head == ring->tail) {
> > +		*mask_id = freed_id;
> > +		return -ENOENT;
> > +	}
> > +
> > +	memcpy(&temp_id, &ring->buf[ring->tail], NFP_FLOWER_MASK_ELEMENT_RS);
> > +	*mask_id = temp_id;
> > +	memcpy(&ring->buf[ring->tail], &freed_id, NFP_FLOWER_MASK_ELEMENT_RS);
> > +	ring->tail = (ring->tail + NFP_FLOWER_MASK_ELEMENT_RS) %
> > +		     (NFP_FLOWER_MASK_ENTRY_RS * NFP_FLOWER_MASK_ELEMENT_RS);
> > +
> > +	getnstimeofday64(&now);
> > +	delta = timespec64_sub(now, priv->mask_ids.last_used[*mask_id]);
> > +
> > +	if (timespec64_to_ns(&delta) < NFP_FL_MASK_REUSE_TIME_NS) {
> > +		nfp_release_mask_id(app, *mask_id);
> 
> nfp_release_mask_id() will reset the time stamp and put the mask at the
> end of the queue.  Is that OK?

I discussed this with Pieter. He believes that it is ok as it would be too
early to use the entry and its better put it to the back of the list and
skip to the next one.

> > +		return -ENOENT;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> 
> > +int nfp_flower_metadata_init(struct nfp_app *app)
> > +{
> > +	struct nfp_flower_priv *priv = app->priv;
> > +
> > +	hash_init(priv->mask_table);
> > +	hash_init(priv->flow_table);
> > +
> > +	/* Init ring buffer and unallocated mask_ids. */
> > +	priv->mask_ids.mask_id_free_list.buf =
> > +		kmalloc(NFP_FLOWER_MASK_ENTRY_RS * NFP_FLOWER_MASK_ELEMENT_RS,
> > +			GFP_KERNEL);
> 
> kmalloc_array, perhaps?  

Yes, indeed. Will do.

> > +	if (!priv->mask_ids.mask_id_free_list.buf)
> > +		return -ENOMEM;
> > +
> > +	priv->mask_ids.init_unallocated = NFP_FLOWER_MASK_ENTRY_RS - 1;
> > +
> > +	/* Init timestamps for mask id*/
> > +	priv->mask_ids.last_used =
> > +		kmalloc_array(NFP_FLOWER_MASK_ENTRY_RS,
> > +			      sizeof(*priv->mask_ids.last_used), GFP_KERNEL);
> > +	if (!priv->mask_ids.last_used) {
> > +		kfree(priv->mask_ids.mask_id_free_list.buf);
> > +		return -ENOMEM;
> > +	}
> > +
> > +	return 0;
> > +}