diff options
Diffstat (limited to 'pkgs/patches-linux-5.15/765-6-net-next-net-dsa-setup-master-before-ports.patch')
| -rw-r--r-- | pkgs/patches-linux-5.15/765-6-net-next-net-dsa-setup-master-before-ports.patch | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/pkgs/patches-linux-5.15/765-6-net-next-net-dsa-setup-master-before-ports.patch b/pkgs/patches-linux-5.15/765-6-net-next-net-dsa-setup-master-before-ports.patch new file mode 100644 index 0000000..93cad0c --- /dev/null +++ b/pkgs/patches-linux-5.15/765-6-net-next-net-dsa-setup-master-before-ports.patch @@ -0,0 +1,115 @@ +From 11fd667dac315ea3f2469961f6d2869271a46cae Mon Sep 17 00:00:00 2001 +From: Vladimir Oltean <vladimir.oltean@nxp.com> +Date: Thu, 6 Jan 2022 01:11:17 +0200 +Subject: [PATCH 6/6] net: dsa: setup master before ports + +It is said that as soon as a network interface is registered, all its +resources should have already been prepared, so that it is available for +sending and receiving traffic. One of the resources needed by a DSA +slave interface is the master. + +dsa_tree_setup +-> dsa_tree_setup_ports + -> dsa_port_setup + -> dsa_slave_create + -> register_netdevice +-> dsa_tree_setup_master + -> dsa_master_setup + -> sets up master->dsa_ptr, which enables reception + +Therefore, there is a short period of time after register_netdevice() +during which the master isn't prepared to pass traffic to the DSA layer +(master->dsa_ptr is checked by eth_type_trans). Same thing during +unregistration, there is a time frame in which packets might be missed. + +Note that this change opens us to another race: dsa_master_find_slave() +will get invoked potentially earlier than the slave creation, and later +than the slave deletion. Since dp->slave starts off as a NULL pointer, +the earlier calls aren't a problem, but the later calls are. To avoid +use-after-free, we should zeroize dp->slave before calling +dsa_slave_destroy(). + +In practice I cannot really test real life improvements brought by this +change, since in my systems, netdevice creation races with PHY autoneg +which takes a few seconds to complete, and that masks quite a few races. +Effects might be noticeable in a setup with fixed links all the way to +an external system. + +Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> +Signed-off-by: David S. Miller <davem@davemloft.net> +--- + net/dsa/dsa2.c | 23 +++++++++++++---------- + 1 file changed, 13 insertions(+), 10 deletions(-) + +--- a/net/dsa/dsa2.c ++++ b/net/dsa/dsa2.c +@@ -545,6 +545,7 @@ static void dsa_port_teardown(struct dsa + struct devlink_port *dlp = &dp->devlink_port; + struct dsa_switch *ds = dp->ds; + struct dsa_mac_addr *a, *tmp; ++ struct net_device *slave; + + if (!dp->setup) + return; +@@ -566,9 +567,11 @@ static void dsa_port_teardown(struct dsa + dsa_port_link_unregister_of(dp); + break; + case DSA_PORT_TYPE_USER: +- if (dp->slave) { +- dsa_slave_destroy(dp->slave); ++ slave = dp->slave; ++ ++ if (slave) { + dp->slave = NULL; ++ dsa_slave_destroy(slave); + } + break; + } +@@ -1130,17 +1133,17 @@ static int dsa_tree_setup(struct dsa_swi + if (err) + goto teardown_cpu_ports; + +- err = dsa_tree_setup_ports(dst); ++ err = dsa_tree_setup_master(dst); + if (err) + goto teardown_switches; + +- err = dsa_tree_setup_master(dst); ++ err = dsa_tree_setup_ports(dst); + if (err) +- goto teardown_ports; ++ goto teardown_master; + + err = dsa_tree_setup_lags(dst); + if (err) +- goto teardown_master; ++ goto teardown_ports; + + dst->setup = true; + +@@ -1148,10 +1151,10 @@ static int dsa_tree_setup(struct dsa_swi + + return 0; + +-teardown_master: +- dsa_tree_teardown_master(dst); + teardown_ports: + dsa_tree_teardown_ports(dst); ++teardown_master: ++ dsa_tree_teardown_master(dst); + teardown_switches: + dsa_tree_teardown_switches(dst); + teardown_cpu_ports: +@@ -1169,10 +1172,10 @@ static void dsa_tree_teardown(struct dsa + + dsa_tree_teardown_lags(dst); + +- dsa_tree_teardown_master(dst); +- + dsa_tree_teardown_ports(dst); + ++ dsa_tree_teardown_master(dst); ++ + dsa_tree_teardown_switches(dst); + + dsa_tree_teardown_cpu_ports(dst); |