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[212.85.90.88]) by smtp.gmail.com with ESMTPSA id n5sm205355lfh.25.2021.04.28.13.29.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 13:29:55 -0700 (PDT) From: Tobias Waldekranz To: Yangbo Lu , netdev@vger.kernel.org Cc: Yangbo Lu , Richard Cochran , Vladimir Oltean , "David S . Miller" , Jakub Kicinski , Jonathan Corbet , Kurt Kanzenbach , Andrew Lunn , Vivien Didelot , Florian Fainelli , Claudiu Manoil , Alexandre Belloni , UNGLinuxDriver@microchip.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [net-next, v2, 3/7] net: dsa: free skb->cb usage in core driver In-Reply-To: <20210426093802.38652-4-yangbo.lu@nxp.com> References: <20210426093802.38652-1-yangbo.lu@nxp.com> <20210426093802.38652-4-yangbo.lu@nxp.com> Date: Wed, 28 Apr 2021 22:29:54 +0200 Message-ID: <87y2d2noe5.fsf@waldekranz.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 26, 2021 at 17:37, Yangbo Lu wrote: > Free skb->cb usage in core driver and let device drivers decide to > use or not. The reason having a DSA_SKB_CB(skb)->clone was because > dsa_skb_tx_timestamp() which may set the clone pointer was called > before p->xmit() which would use the clone if any, and the device > driver has no way to initialize the clone pointer. > > Although for now putting memset(skb->cb, 0, 48) at beginning of > dsa_slave_xmit() by this patch is not very good, there is still way > to improve this. Otherwise, some other new features, like one-step Could you please expand on this improvement? This memset makes it impossible to carry control buffer information from driver callbacks that run before .ndo_start_xmit, for example .ndo_select_queue, to a tagger's .xmit. It seems to me that if the drivers are to handle the CB internally from now on, that should go for both setting and clearing of the required fields. > timestamp which needs a flag of skb marked in dsa_skb_tx_timestamp(), > and handles as one-step timestamp in p->xmit() will face same > situation. > > Signed-off-by: Yangbo Lu > --- > Changes for v2: > - Added this patch. > --- > drivers/net/dsa/ocelot/felix.c | 1 + > drivers/net/dsa/sja1105/sja1105_main.c | 2 +- > drivers/net/dsa/sja1105/sja1105_ptp.c | 4 +++- > drivers/net/ethernet/mscc/ocelot.c | 6 +++--- > drivers/net/ethernet/mscc/ocelot_net.c | 2 +- > include/linux/dsa/sja1105.h | 3 ++- > include/net/dsa.h | 14 -------------- > include/soc/mscc/ocelot.h | 8 ++++++++ > net/dsa/slave.c | 3 +-- > net/dsa/tag_ocelot.c | 8 ++++---- > net/dsa/tag_ocelot_8021q.c | 8 ++++---- > 11 files changed, 28 insertions(+), 31 deletions(-) > > diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c > index d679f023dc00..8980d56ee793 100644 > --- a/drivers/net/dsa/ocelot/felix.c > +++ b/drivers/net/dsa/ocelot/felix.c > @@ -1403,6 +1403,7 @@ static bool felix_txtstamp(struct dsa_switch *ds, int port, > > if (ocelot->ptp && ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) { > ocelot_port_add_txtstamp_skb(ocelot, port, clone); > + OCELOT_SKB_CB(skb)->clone = clone; > return true; > } > > diff --git a/drivers/net/dsa/sja1105/sja1105_main.c b/drivers/net/dsa/sja1105/sja1105_main.c > index d9c198ca0197..405024b637d6 100644 > --- a/drivers/net/dsa/sja1105/sja1105_main.c > +++ b/drivers/net/dsa/sja1105/sja1105_main.c > @@ -3137,7 +3137,7 @@ static void sja1105_port_deferred_xmit(struct kthread_work *work) > struct sk_buff *skb; > > while ((skb = skb_dequeue(&sp->xmit_queue)) != NULL) { > - struct sk_buff *clone = DSA_SKB_CB(skb)->clone; > + struct sk_buff *clone = SJA1105_SKB_CB(skb)->clone; > > mutex_lock(&priv->mgmt_lock); > > diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.c b/drivers/net/dsa/sja1105/sja1105_ptp.c > index 72d052de82d8..0832368aaa96 100644 > --- a/drivers/net/dsa/sja1105/sja1105_ptp.c > +++ b/drivers/net/dsa/sja1105/sja1105_ptp.c > @@ -432,7 +432,7 @@ bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port, > } > > /* Called from dsa_skb_tx_timestamp. This callback is just to make DSA clone > - * the skb and have it available in DSA_SKB_CB in the .port_deferred_xmit > + * the skb and have it available in SJA1105_SKB_CB in the .port_deferred_xmit > * callback, where we will timestamp it synchronously. > */ > bool sja1105_port_txtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb) > @@ -443,6 +443,8 @@ bool sja1105_port_txtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb) > if (!sp->hwts_tx_en) > return false; > > + SJA1105_SKB_CB(skb)->clone = clone; > + > return true; > } > > diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c > index 8d06ffaf318a..7da2dd1632b1 100644 > --- a/drivers/net/ethernet/mscc/ocelot.c > +++ b/drivers/net/ethernet/mscc/ocelot.c > @@ -538,8 +538,8 @@ void ocelot_port_add_txtstamp_skb(struct ocelot *ocelot, int port, > spin_lock(&ocelot_port->ts_id_lock); > > skb_shinfo(clone)->tx_flags |= SKBTX_IN_PROGRESS; > - /* Store timestamp ID in cb[0] of sk_buff */ > - clone->cb[0] = ocelot_port->ts_id; > + /* Store timestamp ID in OCELOT_SKB_CB(clone)->ts_id */ > + OCELOT_SKB_CB(clone)->ts_id = ocelot_port->ts_id; > ocelot_port->ts_id = (ocelot_port->ts_id + 1) % 4; > skb_queue_tail(&ocelot_port->tx_skbs, clone); > > @@ -604,7 +604,7 @@ void ocelot_get_txtstamp(struct ocelot *ocelot) > spin_lock_irqsave(&port->tx_skbs.lock, flags); > > skb_queue_walk_safe(&port->tx_skbs, skb, skb_tmp) { > - if (skb->cb[0] != id) > + if (OCELOT_SKB_CB(skb)->ts_id != id) > continue; > __skb_unlink(skb, &port->tx_skbs); > skb_match = skb; > diff --git a/drivers/net/ethernet/mscc/ocelot_net.c b/drivers/net/ethernet/mscc/ocelot_net.c > index 36f32a4d9b0f..789a5fba146c 100644 > --- a/drivers/net/ethernet/mscc/ocelot_net.c > +++ b/drivers/net/ethernet/mscc/ocelot_net.c > @@ -520,7 +520,7 @@ static netdev_tx_t ocelot_port_xmit(struct sk_buff *skb, struct net_device *dev) > > ocelot_port_add_txtstamp_skb(ocelot, port, clone); > > - rew_op |= clone->cb[0] << 3; > + rew_op |= OCELOT_SKB_CB(clone)->ts_id << 3; > } > } > > diff --git a/include/linux/dsa/sja1105.h b/include/linux/dsa/sja1105.h > index dd93735ae228..1eb84562b311 100644 > --- a/include/linux/dsa/sja1105.h > +++ b/include/linux/dsa/sja1105.h > @@ -47,11 +47,12 @@ struct sja1105_tagger_data { > }; > > struct sja1105_skb_cb { > + struct sk_buff *clone; > u32 meta_tstamp; > }; > > #define SJA1105_SKB_CB(skb) \ > - ((struct sja1105_skb_cb *)DSA_SKB_CB_PRIV(skb)) > + ((struct sja1105_skb_cb *)((skb)->cb)) > > struct sja1105_port { > u16 subvlan_map[DSA_8021Q_N_SUBVLAN]; > diff --git a/include/net/dsa.h b/include/net/dsa.h > index 905066055b08..5685e60cb082 100644 > --- a/include/net/dsa.h > +++ b/include/net/dsa.h > @@ -117,20 +117,6 @@ struct dsa_netdevice_ops { > #define MODULE_ALIAS_DSA_TAG_DRIVER(__proto) \ > MODULE_ALIAS(DSA_TAG_DRIVER_ALIAS __stringify(__proto##_VALUE)) > > -struct dsa_skb_cb { > - struct sk_buff *clone; > -}; > - > -struct __dsa_skb_cb { > - struct dsa_skb_cb cb; > - u8 priv[48 - sizeof(struct dsa_skb_cb)]; > -}; > - > -#define DSA_SKB_CB(skb) ((struct dsa_skb_cb *)((skb)->cb)) > - > -#define DSA_SKB_CB_PRIV(skb) \ > - ((void *)(skb)->cb + offsetof(struct __dsa_skb_cb, priv)) > - > struct dsa_switch_tree { > struct list_head list; > > diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h > index 68cdc7ceaf4d..f075aaf70eee 100644 > --- a/include/soc/mscc/ocelot.h > +++ b/include/soc/mscc/ocelot.h > @@ -689,6 +689,14 @@ struct ocelot_policer { > u32 burst; /* bytes */ > }; > > +struct ocelot_skb_cb { > + struct sk_buff *clone; > + u8 ts_id; > +}; > + > +#define OCELOT_SKB_CB(skb) \ > + ((struct ocelot_skb_cb *)((skb)->cb)) > + > #define ocelot_read_ix(ocelot, reg, gi, ri) __ocelot_read_ix(ocelot, reg, reg##_GSZ * (gi) + reg##_RSZ * (ri)) > #define ocelot_read_gix(ocelot, reg, gi) __ocelot_read_ix(ocelot, reg, reg##_GSZ * (gi)) > #define ocelot_read_rix(ocelot, reg, ri) __ocelot_read_ix(ocelot, reg, reg##_RSZ * (ri)) > diff --git a/net/dsa/slave.c b/net/dsa/slave.c > index acaa52e60d7f..2211894c2381 100644 > --- a/net/dsa/slave.c > +++ b/net/dsa/slave.c > @@ -568,7 +568,6 @@ static void dsa_skb_tx_timestamp(struct dsa_slave_priv *p, > return; > > if (ds->ops->port_txtstamp(ds, p->dp->index, clone)) { > - DSA_SKB_CB(skb)->clone = clone; > return; > } > > @@ -624,7 +623,7 @@ static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev) > > dev_sw_netstats_tx_add(dev, 1, skb->len); > > - DSA_SKB_CB(skb)->clone = NULL; > + memset(skb->cb, 0, 48); > > /* Handle tx timestamp if any */ > dsa_skb_tx_timestamp(p, skb); > diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c > index f9df9cac81c5..1100a16f1032 100644 > --- a/net/dsa/tag_ocelot.c > +++ b/net/dsa/tag_ocelot.c > @@ -15,11 +15,11 @@ static void ocelot_xmit_ptp(struct dsa_port *dp, void *injection, > ocelot_port = ocelot->ports[dp->index]; > rew_op = ocelot_port->ptp_cmd; > > - /* Retrieve timestamp ID populated inside skb->cb[0] of the > - * clone by ocelot_port_add_txtstamp_skb > + /* Retrieve timestamp ID populated inside OCELOT_SKB_CB(clone)->ts_id > + * by ocelot_port_add_txtstamp_skb > */ > if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) > - rew_op |= clone->cb[0] << 3; > + rew_op |= OCELOT_SKB_CB(clone)->ts_id << 3; > > ocelot_ifh_set_rew_op(injection, rew_op); > } > @@ -28,7 +28,7 @@ static void ocelot_xmit_common(struct sk_buff *skb, struct net_device *netdev, > __be32 ifh_prefix, void **ifh) > { > struct dsa_port *dp = dsa_slave_to_port(netdev); > - struct sk_buff *clone = DSA_SKB_CB(skb)->clone; > + struct sk_buff *clone = OCELOT_SKB_CB(skb)->clone; > struct dsa_switch *ds = dp->ds; > void *injection; > __be32 *prefix; > diff --git a/net/dsa/tag_ocelot_8021q.c b/net/dsa/tag_ocelot_8021q.c > index 5f3e8e124a82..a001a7e3f575 100644 > --- a/net/dsa/tag_ocelot_8021q.c > +++ b/net/dsa/tag_ocelot_8021q.c > @@ -28,11 +28,11 @@ static struct sk_buff *ocelot_xmit_ptp(struct dsa_port *dp, > ocelot_port = ocelot->ports[port]; > rew_op = ocelot_port->ptp_cmd; > > - /* Retrieve timestamp ID populated inside skb->cb[0] of the > - * clone by ocelot_port_add_txtstamp_skb > + /* Retrieve timestamp ID populated inside OCELOT_SKB_CB(clone)->ts_id > + * by ocelot_port_add_txtstamp_skb > */ > if (ocelot_port->ptp_cmd == IFH_REW_OP_TWO_STEP_PTP) > - rew_op |= clone->cb[0] << 3; > + rew_op |= OCELOT_SKB_CB(clone)->ts_id << 3; > > ocelot_port_inject_frame(ocelot, port, 0, rew_op, skb); > > @@ -46,7 +46,7 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb, > u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index); > u16 queue_mapping = skb_get_queue_mapping(skb); > u8 pcp = netdev_txq_to_tc(netdev, queue_mapping); > - struct sk_buff *clone = DSA_SKB_CB(skb)->clone; > + struct sk_buff *clone = OCELOT_SKB_CB(skb)->clone; > > /* TX timestamping was requested, so inject through MMIO */ > if (clone) > -- > 2.25.1