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These patches have been accepted upstream for linux 5.13. Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
105 lines
4.1 KiB
Diff
105 lines
4.1 KiB
Diff
From a3b0b6479700a5b0af2c631cb2ec0fb7a0d978f2 Mon Sep 17 00:00:00 2001
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From: Vladimir Oltean <vladimir.oltean@nxp.com>
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Date: Sun, 1 Nov 2020 21:16:09 +0200
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Subject: [PATCH] net: dsa: implement a central TX reallocation procedure
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At the moment, taggers are left with the task of ensuring that the skb
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headers are writable (which they aren't, if the frames were cloned for
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TX timestamping, for flooding by the bridge, etc), and that there is
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enough space in the skb data area for the DSA tag to be pushed.
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Moreover, the life of tail taggers is even harder, because they need to
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ensure that short frames have enough padding, a problem that normal
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taggers don't have.
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The principle of the DSA framework is that everything except for the
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most intimate hardware specifics (like in this case, the actual packing
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of the DSA tag bits) should be done inside the core, to avoid having
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code paths that are very rarely tested.
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So provide a TX reallocation procedure that should cover the known needs
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of DSA today.
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Note that this patch also gives the network stack a good hint about the
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headroom/tailroom it's going to need. Up till now it wasn't doing that.
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So the reallocation procedure should really be there only for the
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exceptional cases, and for cloned packets which need to be unshared.
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Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
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Tested-by: Christian Eggers <ceggers@arri.de> # For tail taggers only
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Tested-by: Kurt Kanzenbach <kurt@linutronix.de>
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Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
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Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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---
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net/dsa/slave.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
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1 file changed, 45 insertions(+)
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--- a/net/dsa/slave.c
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+++ b/net/dsa/slave.c
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@@ -548,6 +548,30 @@ netdev_tx_t dsa_enqueue_skb(struct sk_bu
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}
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EXPORT_SYMBOL_GPL(dsa_enqueue_skb);
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+static int dsa_realloc_skb(struct sk_buff *skb, struct net_device *dev)
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+{
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+ int needed_headroom = dev->needed_headroom;
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+ int needed_tailroom = dev->needed_tailroom;
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+
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+ /* For tail taggers, we need to pad short frames ourselves, to ensure
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+ * that the tail tag does not fail at its role of being at the end of
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+ * the packet, once the master interface pads the frame. Account for
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+ * that pad length here, and pad later.
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+ */
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+ if (unlikely(needed_tailroom && skb->len < ETH_ZLEN))
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+ needed_tailroom += ETH_ZLEN - skb->len;
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+ /* skb_headroom() returns unsigned int... */
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+ needed_headroom = max_t(int, needed_headroom - skb_headroom(skb), 0);
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+ needed_tailroom = max_t(int, needed_tailroom - skb_tailroom(skb), 0);
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+
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+ if (likely(!needed_headroom && !needed_tailroom && !skb_cloned(skb)))
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+ /* No reallocation needed, yay! */
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+ return 0;
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+
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+ return pskb_expand_head(skb, needed_headroom, needed_tailroom,
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+ GFP_ATOMIC);
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+}
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+
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static netdev_tx_t dsa_slave_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct dsa_slave_priv *p = netdev_priv(dev);
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@@ -567,6 +591,17 @@ static netdev_tx_t dsa_slave_xmit(struct
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*/
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dsa_skb_tx_timestamp(p, skb);
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+ if (dsa_realloc_skb(skb, dev)) {
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+ dev_kfree_skb_any(skb);
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+ return NETDEV_TX_OK;
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+ }
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+
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+ /* needed_tailroom should still be 'warm' in the cache line from
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+ * dsa_realloc_skb(), which has also ensured that padding is safe.
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+ */
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+ if (dev->needed_tailroom)
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+ eth_skb_pad(skb);
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+
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/* Transmit function may have to reallocate the original SKB,
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* in which case it must have freed it. Only free it here on error.
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*/
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@@ -1825,6 +1860,16 @@ int dsa_slave_create(struct dsa_port *po
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slave_dev->netdev_ops = &dsa_slave_netdev_ops;
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if (ds->ops->port_max_mtu)
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slave_dev->max_mtu = ds->ops->port_max_mtu(ds, port->index);
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+ if (cpu_dp->tag_ops->tail_tag)
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+ slave_dev->needed_tailroom = cpu_dp->tag_ops->overhead;
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+ else
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+ slave_dev->needed_headroom = cpu_dp->tag_ops->overhead;
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+ /* Try to save one extra realloc later in the TX path (in the master)
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+ * by also inheriting the master's needed headroom and tailroom.
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+ * The 8021q driver also does this.
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+ */
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+ slave_dev->needed_headroom += master->needed_headroom;
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+ slave_dev->needed_tailroom += master->needed_tailroom;
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SET_NETDEV_DEVTYPE(slave_dev, &dsa_type);
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netdev_for_each_tx_queue(slave_dev, dsa_slave_set_lockdep_class_one,
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