On 10/12/2017 03:10 PM, Vivien Didelot wrote:
> An Ethernet switch may support having a MAC address, which can be used
> as the switch's source address in transmitted full-duplex Pause frames.
>
> If a DSA switch supports the related .set_addr operation, the DSA core
> sets the master's MAC address on the switch.
>
> This won't make sense anymore in a multi-CPU ports system, because there
> won't be a unique master device assigned to a switch tree.
Thus far, everything you have said is true, but why we should do it,
that is: what if we don't, needs to be explained. Does that create a
problem with the generation of pause frames throughout the switch fabric?
>
> To fix this, assign a random MAC address to the switch chip instead.
Maybe this is something that should be removed entirely from the DSA
core and pushed into the individual switch drivers instead. dsa_loop
implements it for code coverage, but that does not do anything.
set_addr is confusing in that you may think it could be used to program
the switch with the MAC address of the CPU/management port such that you
can disable MAC address learning on said port, but in fact, that's not
how it is used.
>
> Signed-off-by: Vivien Didelot <vivien.dide...@savoirfairelinux.com>
> ---
> net/dsa/dsa2.c | 8 +++-----
> net/dsa/dsa_priv.h | 1 +
> net/dsa/legacy.c | 8 +++-----
> net/dsa/switch.c | 17 +++++++++++++++++
> 4 files changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
> index 54ed054777bd..8e5780ddd7f9 100644
> --- a/net/dsa/dsa2.c
> +++ b/net/dsa/dsa2.c
> @@ -336,11 +336,9 @@ static int dsa_ds_apply(struct dsa_switch_tree *dst,
> struct dsa_switch *ds)
> if (err)
> return err;
>
> - if (ds->ops->set_addr) {
> - err = ds->ops->set_addr(ds, dst->cpu_dp->netdev->dev_addr);
> - if (err < 0)
> - return err;
> - }
> + err = dsa_switch_set_addr(ds);
> + if (err)
> + return err;
>
> if (!ds->slave_mii_bus && ds->ops->phy_read) {
> ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
> diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
> index 2850077cc9cc..9c4c17a4bd6b 100644
> --- a/net/dsa/dsa_priv.h
> +++ b/net/dsa/dsa_priv.h
> @@ -172,6 +172,7 @@ void dsa_slave_unregister_notifier(void);
> /* switch.c */
> int dsa_switch_register_notifier(struct dsa_switch *ds);
> void dsa_switch_unregister_notifier(struct dsa_switch *ds);
> +int dsa_switch_set_addr(struct dsa_switch *ds);
>
> /* tag_brcm.c */
> extern const struct dsa_device_ops brcm_netdev_ops;
> diff --git a/net/dsa/legacy.c b/net/dsa/legacy.c
> index 19ff6e0a21dc..340ca7997271 100644
> --- a/net/dsa/legacy.c
> +++ b/net/dsa/legacy.c
> @@ -172,11 +172,9 @@ static int dsa_switch_setup_one(struct dsa_switch *ds,
> if (ret)
> return ret;
>
> - if (ops->set_addr) {
> - ret = ops->set_addr(ds, master->dev_addr);
> - if (ret < 0)
> - return ret;
> - }
> + ret = dsa_switch_set_addr(ds);
> + if (ret)
> + return ret;
>
> if (!ds->slave_mii_bus && ops->phy_read) {
> ds->slave_mii_bus = devm_mdiobus_alloc(ds->dev);
> diff --git a/net/dsa/switch.c b/net/dsa/switch.c
> index e6c06aa349a6..b45a26b006af 100644
> --- a/net/dsa/switch.c
> +++ b/net/dsa/switch.c
> @@ -10,6 +10,7 @@
> * (at your option) any later version.
> */
>
> +#include <linux/etherdevice.h>
> #include <linux/netdevice.h>
> #include <linux/notifier.h>
> #include <net/switchdev.h>
> @@ -267,3 +268,19 @@ void dsa_switch_unregister_notifier(struct dsa_switch
> *ds)
> if (err)
> dev_err(ds->dev, "failed to unregister notifier (%d)\n", err);
> }
> +
> +int dsa_switch_set_addr(struct dsa_switch *ds)
> +{
> + u8 addr[6];
> + int err;
> +
> + if (ds->ops->set_addr) {
> + eth_random_addr(addr);
> +
> + err = ds->ops->set_addr(ds, addr);
> + if (err)
> + return err;
> + }
> +
> + return 0;
> +}
>
--
Florian
