diff options
Diffstat (limited to 'pkgs/patches-linux-5.15/700-net-next-net-dsa-introduce-tagger-owned-storage-for-private.patch')
| -rw-r--r-- | pkgs/patches-linux-5.15/700-net-next-net-dsa-introduce-tagger-owned-storage-for-private.patch | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/pkgs/patches-linux-5.15/700-net-next-net-dsa-introduce-tagger-owned-storage-for-private.patch b/pkgs/patches-linux-5.15/700-net-next-net-dsa-introduce-tagger-owned-storage-for-private.patch new file mode 100644 index 0000000..fe47c17 --- /dev/null +++ b/pkgs/patches-linux-5.15/700-net-next-net-dsa-introduce-tagger-owned-storage-for-private.patch @@ -0,0 +1,279 @@ +From dc452a471dbae8aca8257c565174212620880093 Mon Sep 17 00:00:00 2001 +From: Vladimir Oltean <vladimir.oltean@nxp.com> +Date: Fri, 10 Dec 2021 01:34:37 +0200 +Subject: net: dsa: introduce tagger-owned storage for private and shared data + +Ansuel is working on register access over Ethernet for the qca8k switch +family. This requires the qca8k tagging protocol driver to receive +frames which aren't intended for the network stack, but instead for the +qca8k switch driver itself. + +The dp->priv is currently the prevailing method for passing data back +and forth between the tagging protocol driver and the switch driver. +However, this method is riddled with caveats. + +The DSA design allows in principle for any switch driver to return any +protocol it desires in ->get_tag_protocol(). The dsa_loop driver can be +modified to do just that. But in the current design, the memory behind +dp->priv has to be allocated by the switch driver, so if the tagging +protocol is paired to an unexpected switch driver, we may end up in NULL +pointer dereferences inside the kernel, or worse (a switch driver may +allocate dp->priv according to the expectations of a different tagger). + +The latter possibility is even more plausible considering that DSA +switches can dynamically change tagging protocols in certain cases +(dsa <-> edsa, ocelot <-> ocelot-8021q), and the current design lends +itself to mistakes that are all too easy to make. + +This patch proposes that the tagging protocol driver should manage its +own memory, instead of relying on the switch driver to do so. +After analyzing the different in-tree needs, it can be observed that the +required tagger storage is per switch, therefore a ds->tagger_data +pointer is introduced. In principle, per-port storage could also be +introduced, although there is no need for it at the moment. Future +changes will replace the current usage of dp->priv with ds->tagger_data. + +We define a "binding" event between the DSA switch tree and the tagging +protocol. During this binding event, the tagging protocol's ->connect() +method is called first, and this may allocate some memory for each +switch of the tree. Then a cross-chip notifier is emitted for the +switches within that tree, and they are given the opportunity to fix up +the tagger's memory (for example, they might set up some function +pointers that represent virtual methods for consuming packets). +Because the memory is owned by the tagger, there exists a ->disconnect() +method for the tagger (which is the place to free the resources), but +there doesn't exist a ->disconnect() method for the switch driver. +This is part of the design. The switch driver should make minimal use of +the public part of the tagger data, and only after type-checking it +using the supplied "proto" argument. + +In the code there are in fact two binding events, one is the initial +event in dsa_switch_setup_tag_protocol(). At this stage, the cross chip +notifier chains aren't initialized, so we call each switch's connect() +method by hand. Then there is dsa_tree_bind_tag_proto() during +dsa_tree_change_tag_proto(), and here we have an old protocol and a new +one. We first connect to the new one before disconnecting from the old +one, to simplify error handling a bit and to ensure we remain in a valid +state at all times. + +Co-developed-by: Ansuel Smith <ansuelsmth@gmail.com> +Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> +Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> +Signed-off-by: David S. Miller <davem@davemloft.net> +--- + include/net/dsa.h | 12 +++++++++ + net/dsa/dsa2.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++--- + net/dsa/dsa_priv.h | 1 + + net/dsa/switch.c | 14 +++++++++++ + 4 files changed, 96 insertions(+), 4 deletions(-) + +--- a/include/net/dsa.h ++++ b/include/net/dsa.h +@@ -80,12 +80,15 @@ enum dsa_tag_protocol { + }; + + struct dsa_switch; ++struct dsa_switch_tree; + + struct dsa_device_ops { + struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev); + struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev); + void (*flow_dissect)(const struct sk_buff *skb, __be16 *proto, + int *offset); ++ int (*connect)(struct dsa_switch_tree *dst); ++ void (*disconnect)(struct dsa_switch_tree *dst); + unsigned int needed_headroom; + unsigned int needed_tailroom; + const char *name; +@@ -329,6 +332,8 @@ struct dsa_switch { + */ + void *priv; + ++ void *tagger_data; ++ + /* + * Configuration data for this switch. + */ +@@ -584,6 +589,13 @@ struct dsa_switch_ops { + enum dsa_tag_protocol mprot); + int (*change_tag_protocol)(struct dsa_switch *ds, int port, + enum dsa_tag_protocol proto); ++ /* ++ * Method for switch drivers to connect to the tagging protocol driver ++ * in current use. The switch driver can provide handlers for certain ++ * types of packets for switch management. ++ */ ++ int (*connect_tag_protocol)(struct dsa_switch *ds, ++ enum dsa_tag_protocol proto); + + /* Optional switch-wide initialization and destruction methods */ + int (*setup)(struct dsa_switch *ds); +--- a/net/dsa/dsa2.c ++++ b/net/dsa/dsa2.c +@@ -230,8 +230,12 @@ static struct dsa_switch_tree *dsa_tree_ + + static void dsa_tree_free(struct dsa_switch_tree *dst) + { +- if (dst->tag_ops) ++ if (dst->tag_ops) { ++ if (dst->tag_ops->disconnect) ++ dst->tag_ops->disconnect(dst); ++ + dsa_tag_driver_put(dst->tag_ops); ++ } + list_del(&dst->list); + kfree(dst); + } +@@ -805,7 +809,7 @@ static int dsa_switch_setup_tag_protocol + int port, err; + + if (tag_ops->proto == dst->default_proto) +- return 0; ++ goto connect; + + for (port = 0; port < ds->num_ports; port++) { + if (!dsa_is_cpu_port(ds, port)) +@@ -821,6 +825,17 @@ static int dsa_switch_setup_tag_protocol + } + } + ++connect: ++ if (ds->ops->connect_tag_protocol) { ++ err = ds->ops->connect_tag_protocol(ds, tag_ops->proto); ++ if (err) { ++ dev_err(ds->dev, ++ "Unable to connect to tag protocol \"%s\": %pe\n", ++ tag_ops->name, ERR_PTR(err)); ++ return err; ++ } ++ } ++ + return 0; + } + +@@ -1132,6 +1147,46 @@ static void dsa_tree_teardown(struct dsa + dst->setup = false; + } + ++static int dsa_tree_bind_tag_proto(struct dsa_switch_tree *dst, ++ const struct dsa_device_ops *tag_ops) ++{ ++ const struct dsa_device_ops *old_tag_ops = dst->tag_ops; ++ struct dsa_notifier_tag_proto_info info; ++ int err; ++ ++ dst->tag_ops = tag_ops; ++ ++ /* Notify the new tagger about the connection to this tree */ ++ if (tag_ops->connect) { ++ err = tag_ops->connect(dst); ++ if (err) ++ goto out_revert; ++ } ++ ++ /* Notify the switches from this tree about the connection ++ * to the new tagger ++ */ ++ info.tag_ops = tag_ops; ++ err = dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO_CONNECT, &info); ++ if (err && err != -EOPNOTSUPP) ++ goto out_disconnect; ++ ++ /* Notify the old tagger about the disconnection from this tree */ ++ if (old_tag_ops->disconnect) ++ old_tag_ops->disconnect(dst); ++ ++ return 0; ++ ++out_disconnect: ++ /* Revert the new tagger's connection to this tree */ ++ if (tag_ops->disconnect) ++ tag_ops->disconnect(dst); ++out_revert: ++ dst->tag_ops = old_tag_ops; ++ ++ return err; ++} ++ + /* Since the dsa/tagging sysfs device attribute is per master, the assumption + * is that all DSA switches within a tree share the same tagger, otherwise + * they would have formed disjoint trees (different "dsa,member" values). +@@ -1164,12 +1219,15 @@ int dsa_tree_change_tag_proto(struct dsa + goto out_unlock; + } + ++ /* Notify the tag protocol change */ + info.tag_ops = tag_ops; + err = dsa_tree_notify(dst, DSA_NOTIFIER_TAG_PROTO, &info); + if (err) +- goto out_unwind_tagger; ++ return err; + +- dst->tag_ops = tag_ops; ++ err = dsa_tree_bind_tag_proto(dst, tag_ops); ++ if (err) ++ goto out_unwind_tagger; + + rtnl_unlock(); + +@@ -1257,6 +1315,7 @@ static int dsa_port_parse_cpu(struct dsa + struct dsa_switch_tree *dst = ds->dst; + const struct dsa_device_ops *tag_ops; + enum dsa_tag_protocol default_proto; ++ int err; + + /* Find out which protocol the switch would prefer. */ + default_proto = dsa_get_tag_protocol(dp, master); +@@ -1304,6 +1363,12 @@ static int dsa_port_parse_cpu(struct dsa + */ + dsa_tag_driver_put(tag_ops); + } else { ++ if (tag_ops->connect) { ++ err = tag_ops->connect(dst); ++ if (err) ++ return err; ++ } ++ + dst->tag_ops = tag_ops; + } + +--- a/net/dsa/dsa_priv.h ++++ b/net/dsa/dsa_priv.h +@@ -37,6 +37,7 @@ enum { + DSA_NOTIFIER_VLAN_DEL, + DSA_NOTIFIER_MTU, + DSA_NOTIFIER_TAG_PROTO, ++ DSA_NOTIFIER_TAG_PROTO_CONNECT, + DSA_NOTIFIER_MRP_ADD, + DSA_NOTIFIER_MRP_DEL, + DSA_NOTIFIER_MRP_ADD_RING_ROLE, +--- a/net/dsa/switch.c ++++ b/net/dsa/switch.c +@@ -616,6 +616,17 @@ static int dsa_switch_change_tag_proto(s + return 0; + } + ++static int dsa_switch_connect_tag_proto(struct dsa_switch *ds, ++ struct dsa_notifier_tag_proto_info *info) ++{ ++ const struct dsa_device_ops *tag_ops = info->tag_ops; ++ ++ if (!ds->ops->connect_tag_protocol) ++ return -EOPNOTSUPP; ++ ++ return ds->ops->connect_tag_protocol(ds, tag_ops->proto); ++} ++ + static int dsa_switch_mrp_add(struct dsa_switch *ds, + struct dsa_notifier_mrp_info *info) + { +@@ -735,6 +746,9 @@ static int dsa_switch_event(struct notif + case DSA_NOTIFIER_TAG_PROTO: + err = dsa_switch_change_tag_proto(ds, info); + break; ++ case DSA_NOTIFIER_TAG_PROTO_CONNECT: ++ err = dsa_switch_connect_tag_proto(ds, info); ++ break; + case DSA_NOTIFIER_MRP_ADD: + err = dsa_switch_mrp_add(ds, info); + break; |