[PATCH] net: dsa: Inherit dev addr from master

[PATCH] net: dsa: Inherit dev addr from master

[Vinod Koul]

From: Xiaofei Shen <xiaofeis@codeaurora.org>

When we create slave netdevice, the dev addr is inherited from master
but the master dev addr maybe NULL at that time, so inherit it again
while opening the slave.

Signed-off-by: Xiaofei Shen <xiaofeis@codeaurora.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 net/dsa/slave.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 8e64c4e947c6..5f95c538b58c 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -77,7 +77,9 @@ static int dsa_slave_open(struct net_device *dev)
 	if (!(master->flags & IFF_UP))
 		return -ENETDOWN;
 
-	if (!ether_addr_equal(dev->dev_addr, master->dev_addr)) {
+	if (!is_valid_ether_addr(dev->dev_addr)) {
+		eth_hw_addr_inherit(dev, master);
+	} else if (!ether_addr_equal(dev->dev_addr, master->dev_addr)) {
 		err = dev_uc_add(master, dev->dev_addr);
 		if (err < 0)
 			goto out;
-- 
2.20.1

Re: [PATCH] net: dsa: Inherit dev addr from master

[Andrew Lunn]

On Fri, Feb 22, 2019 at 06:26:54PM +0530, Vinod Koul wrote:
> From: Xiaofei Shen <xiaofeis@codeaurora.org>
> 
> When we create slave netdevice, the dev addr is inherited from master
> but the master dev addr maybe NULL at that time, so inherit it again
> while opening the slave.

Hi Xiaofei, Vinod

Inheriting it twice seems a bit clumsy. Can the first inherit be
removed? Can you change your MAC driver to set its MAC address in
probe?

	Andrew

Re: [PATCH] net: dsa: Inherit dev addr from master

[xiaofeis]

On 2019-02-22 22:30, Andrew Lunn wrote:
> On Fri, Feb 22, 2019 at 06:26:54PM +0530, Vinod Koul wrote:
>> From: Xiaofei Shen <xiaofeis@codeaurora.org>
>> 
>> When we create slave netdevice, the dev addr is inherited from master
>> but the master dev addr maybe NULL at that time, so inherit it again
>> while opening the slave.
> 
> Hi Xiaofei, Vinod
> 
> Inheriting it twice seems a bit clumsy. Can the first inherit be
> removed? Can you change your MAC driver to set its MAC address in
> probe?
> 
> 	Andrew
Hi Andrew

Some mac driver set its MAC address in probe while some MAC driver do it 
in the open function in the kernel.


This patch is checking whether the address is valid firstly, if it 
already inherits a valid mac address, it will not inherit again.

I think we can remove the first inherit, but if keep it, we can see 
consistent address output by ifconfig -a before open master and slave 
interface.

Xiaofeis

Re: [PATCH] net: dsa: Inherit dev addr from master

[Andrew Lunn]

> I think we can remove the first inherit, but if keep it, we can see
> consistent address output by ifconfig -a before open master and slave
> interface.

True

But it also means we see inconsistent MAC addresses on the master. The
MAC address changes on open.

Maybe it would be better to change your master so it sets its MAC
address during probe? Everything is then consistent all the time.

	Andrew

Re: [PATCH] net: dsa: Inherit dev addr from master

[xiaofeis]

On 2019-02-25 21:21, Andrew Lunn wrote:
>> I think we can remove the first inherit, but if keep it, we can see
>> consistent address output by ifconfig -a before open master and slave
>> interface.
> 
> True
> 
> But it also means we see inconsistent MAC addresses on the master. The
> MAC address changes on open.
> 
> Maybe it would be better to change your master so it sets its MAC
> address during probe? Everything is then consistent all the time.
> 
> 	Andrew
I'm trying to suggest our master driver owner to set MAC address during 
probe.

I found in kernel, different driver has different implementation, some 
set it in probe, while
some in open. DSA should be generic to work with all these master 
drivers. I think this change
can help. Thanks.