netdev - RE: [PATCH net-next 3/4] net: renesas: rswitch: Remove gptp flag from rswitch_gwca

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Date:   Wed, 8 Feb 2023 23:33:06 +0000
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     Alexander H Duyck <alexander.duyck@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH net-next 3/4] net: renesas: rswitch: Remove gptp flag from
 rswitch_gwca_queue

Hi Alexander,

> From: Alexander H Duyck, Sent: Thursday, February 9, 2023 1:07 AM
> 
> On Wed, 2023-02-08 at 16:34 +0900, Yoshihiro Shimoda wrote:
> > The gptp flag is completely related to the !dir_tx in struct
> > rswitch_gwca_queue. In the future, a new queue handling for
> > timestamp will be implemented and this gptp flag is confusable.
> > So, remove the gptp flag.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
> 
> Based on these changes I am assuming that gptp == !dir_tx? Am I
> understanding it correctly? It would be useful if you called that out
> in the patch description.

You're correct.
I'll modify the description to clear why gptp == !dir_tx like below on v2 patch.
---
In the previous code, the gptp flag was completely related to the !dir_tx
in struct rswitch_gwca_queue because rswitch_gwca_queue_alloc() was called
below:

< In rswitch_txdmac_alloc() >
err = rswitch_gwca_queue_alloc(ndev, priv, rdev->tx_queue, true, false,
			      TX_RING_SIZE);
So, dir_tx = true, gptp = false

< In rswitch_rxdmac_alloc() >
err = rswitch_gwca_queue_alloc(ndev, priv, rdev->rx_queue, false, true,
			      RX_RING_SIZE);
So, dir_tx = false, gptp = true

In the future, a new queue handling for timestamp will be implemented
and this gptp flag is confusable. So, remove the gptp flag.
---

> > ---
> >  drivers/net/ethernet/renesas/rswitch.c | 26 +++++++++++---------------
> >  drivers/net/ethernet/renesas/rswitch.h |  1 -
> >  2 files changed, 11 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> > index b256dadada1d..e408d10184e8 100644
> > --- a/drivers/net/ethernet/renesas/rswitch.c
> > +++ b/drivers/net/ethernet/renesas/rswitch.c
> > @@ -280,11 +280,14 @@ static void rswitch_gwca_queue_free(struct net_device *ndev,
> >  {
> >  	int i;
> >
> > -	if (gq->gptp) {
> > +	if (!gq->dir_tx) {
> >  		dma_free_coherent(ndev->dev.parent,
> >  				  sizeof(struct rswitch_ext_ts_desc) *
> >  				  (gq->ring_size + 1), gq->rx_ring, gq->ring_dma);
> >  		gq->rx_ring = NULL;
> > +
> > +		for (i = 0; i < gq->ring_size; i++)
> > +			dev_kfree_skb(gq->skbs[i]);
> >  	} else {
> >  		dma_free_coherent(ndev->dev.parent,
> >  				  sizeof(struct rswitch_ext_desc) *
> > @@ -292,11 +295,6 @@ static void rswitch_gwca_queue_free(struct net_device *ndev,
> >  		gq->tx_ring = NULL;
> >  	}
> >
> > -	if (!gq->dir_tx) {
> > -		for (i = 0; i < gq->ring_size; i++)
> > -			dev_kfree_skb(gq->skbs[i]);
> > -	}
> > -
> >  	kfree(gq->skbs);
> >  	gq->skbs = NULL;
> >  }
> 
> One piece I don't understand is why freeing of the skbs stored in the
> array here was removed. Is this cleaned up somewhere else before we
> call this function?

"gq->skbs = NULL;" seems unnecessary because this driver doesn't check
whether gq->skbs is NULL or not. Also, gq->[rt]x_ring seem to be the same.
So, I'll make such a patch which is removing unnecessary code after
this patch series was accepted.

Best regards,
Yoshihiro Shimoda