Am 2022-01-25 11:24, schrieb Rafał Miłecki:

On 28.12.2021 15:25, Michael Walle wrote:

quoted

Add a helper to add an offset to a ethernet address. This comes in 
handy
if you have a base ethernet address for multiple interfaces.

Signed-off-by: Michael Walle <redacted>
---
  include/linux/etherdevice.h | 14 ++++++++++++++
  1 file changed, 14 insertions(+)

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 2ad71cc90b37..9d621dc85290 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h

@@ -486,6 +486,20 @@ static inline void eth_addr_inc(u8 *addr)
  	u64_to_ether_addr(u, addr);
  }
  +/**
+ * eth_addr_add() - Add (or subtract) and offset to/from the given 

MAC address.
+ *
+ * @offset: Offset to add.
+ * @addr: Pointer to a six-byte array containing Ethernet address to 
increment.
+ */
+static inline void eth_addr_add(u8 *addr, long offset)
+{
+	u64 u = ether_addr_to_u64(addr);
+
+	u += offset;
+	u64_to_ether_addr(u, addr);
+}

Please check eth_hw_addr_gen() which contains identical code +
eth_hw_addr_set().

You should probably make eth_hw_addr_gen() use your new function as a
helper.

You'd need to copy the mac address first because eth_addr_add()
modifies the mac address in place. I don't see that this is
improving anything.

-michael