netdev - RE: [PATCH v2 net 2/9] net: enetc: correct the tx

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID:
 <PAXPR04MB8510D3ACAB9DD6C86AC87E5488C72@PAXPR04MB8510.eurprd04.prod.outlook.com>
Date: Fri, 21 Feb 2025 01:42:05 +0000
From: Wei Fang <wei.fang@....com>
To: Vladimir Oltean <vladimir.oltean@....com>
CC: Claudiu Manoil <claudiu.manoil@....com>, Clark Wang
	<xiaoning.wang@....com>, "andrew+netdev@...n.ch" <andrew+netdev@...n.ch>,
	"davem@...emloft.net" <davem@...emloft.net>, "edumazet@...gle.com"
	<edumazet@...gle.com>, "kuba@...nel.org" <kuba@...nel.org>,
	"pabeni@...hat.com" <pabeni@...hat.com>, Ioana Ciornei
	<ioana.ciornei@....com>, "Y.B. Lu" <yangbo.lu@....com>,
	"michal.swiatkowski@...ux.intel.com" <michal.swiatkowski@...ux.intel.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "stable@...r.kernel.org"
	<stable@...r.kernel.org>
Subject: RE: [PATCH v2 net 2/9] net: enetc: correct the tx_swbd statistics

> I'm not sure "correct the statistics" is the best way to describe this
> change. Maybe "keep track of correct TXBD count in
> enetc_map_tx_tso_buffs()"?

Hi Vladimir,

Inspired by Michal, I think we don't need to keep the count variable, because
we already have index "i", we just need to record the value of the initial i at the
beginning. So I plan to do this optimization on the net-next tree in the future.
So I don't think it is necessary to modify enetc_map_tx_tso_hdr().

> The bug is that not all TX buffers are freed on error, not that some
> statistics are wrong.
> 
> >  drivers/net/ethernet/freescale/enetc/enetc.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c
> b/drivers/net/ethernet/freescale/enetc/enetc.c
> > index 01c09fd26f9f..0658c06a23c1 100644
> > --- a/drivers/net/ethernet/freescale/enetc/enetc.c
> > +++ b/drivers/net/ethernet/freescale/enetc/enetc.c
> > @@ -759,6 +759,7 @@ static int enetc_lso_hw_offload(struct enetc_bdr
> *tx_ring, struct sk_buff *skb)
> >  static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff
> *skb)
> >  {
> >  	struct enetc_ndev_priv *priv = netdev_priv(tx_ring->ndev);
> > +	bool ext_bd = skb_vlan_tag_present(skb);
> >  	int hdr_len, total_len, data_len;
> >  	struct enetc_tx_swbd *tx_swbd;
> >  	union enetc_tx_bd *txbd;
> > @@ -792,7 +793,7 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr
> *tx_ring, struct sk_buff *skb
> >  		csum = enetc_tso_hdr_csum(&tso, skb, hdr, hdr_len, &pos);
> >  		enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i, hdr_len,
> data_len);
> >  		bd_data_num = 0;
> > -		count++;
> > +		count += ext_bd ? 2 : 1;
> >
> >  		while (data_len > 0) {
> >  			int size;
> > --
> > 2.34.1
> >
> 
> stylistic nitpick: I think this implementation choice obscures the fact,
> to an unfamiliar reader, that the requirement for an extended TXBD comes
> from enetc_map_tx_tso_hdr(). This is because you repeat the condition
> for skb_vlan_tag_present(), but it's not obvious it's correlated to the
> other one. Something like the change below is more expressive in this
> regard, in my opinion:
> 
> diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c
> b/drivers/net/ethernet/freescale/enetc/enetc.c
> index fe3967268a19..6178157611db 100644
> --- a/drivers/net/ethernet/freescale/enetc/enetc.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc.c
> @@ -410,14 +410,15 @@ static int enetc_map_tx_buffs(struct enetc_bdr
> *tx_ring, struct sk_buff *skb)
>  	return 0;
>  }
> 
> -static void enetc_map_tx_tso_hdr(struct enetc_bdr *tx_ring, struct sk_buff
> *skb,
> -				 struct enetc_tx_swbd *tx_swbd,
> -				 union enetc_tx_bd *txbd, int *i, int hdr_len,
> -				 int data_len)
> +static int enetc_map_tx_tso_hdr(struct enetc_bdr *tx_ring, struct sk_buff
> *skb,
> +				struct enetc_tx_swbd *tx_swbd,
> +				union enetc_tx_bd *txbd, int *i, int hdr_len,
> +				int data_len)
>  {
>  	union enetc_tx_bd txbd_tmp;
>  	u8 flags = 0, e_flags = 0;
>  	dma_addr_t addr;
> +	int count = 1;
> 
>  	enetc_clear_tx_bd(&txbd_tmp);
>  	addr = tx_ring->tso_headers_dma + *i * TSO_HEADER_SIZE;
> @@ -460,7 +461,10 @@ static void enetc_map_tx_tso_hdr(struct enetc_bdr
> *tx_ring, struct sk_buff *skb,
>  		/* Write the BD */
>  		txbd_tmp.ext.e_flags = e_flags;
>  		*txbd = txbd_tmp;
> +		count++;
>  	}
> +
> +	return count;
>  }
> 
>  static int enetc_map_tx_tso_data(struct enetc_bdr *tx_ring, struct sk_buff
> *skb,
> @@ -786,7 +790,6 @@ static int enetc_lso_hw_offload(struct enetc_bdr
> *tx_ring, struct sk_buff *skb)
>  static int enetc_map_tx_tso_buffs(struct enetc_bdr *tx_ring, struct sk_buff
> *skb)
>  {
>  	struct enetc_ndev_priv *priv = netdev_priv(tx_ring->ndev);
> -	bool ext_bd = skb_vlan_tag_present(skb);
>  	int hdr_len, total_len, data_len;
>  	struct enetc_tx_swbd *tx_swbd;
>  	union enetc_tx_bd *txbd;
> @@ -818,9 +821,9 @@ static int enetc_map_tx_tso_buffs(struct enetc_bdr
> *tx_ring, struct sk_buff *skb
> 
>  		/* compute the csum over the L4 header */
>  		csum = enetc_tso_hdr_csum(&tso, skb, hdr, hdr_len, &pos);
> -		enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i, hdr_len,
> data_len);
> +		count += enetc_map_tx_tso_hdr(tx_ring, skb, tx_swbd, txbd, &i,
> +					      hdr_len, data_len);
>  		bd_data_num = 0;
> -		count += ext_bd ? 2 : 1;
> 
>  		while (data_len > 0) {
>  			int size;