2018-07-19 10:48 GMT+02:00 Dan Carpenter <dan.carpenter@xxxxxxxxxx>:
> On Thu, Jul 19, 2018 at 10:20:27AM +0200, Bartosz Golaszewski wrote:
>> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>>
>> Many non-DT platforms read the MAC address from EEPROM. Usually it's
>> either done with callbacks defined in board files or from SoC-specific
>> ethernet drivers.
>>
>> In order to generalize this, try to read the MAC from nvmem in
>> eth_platform_get_mac_address() using a standard lookup name:
>> "mac-address".
>>
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>> ---
>> net/ethernet/eth.c | 27 +++++++++++++++++++++++++++
>> 1 file changed, 27 insertions(+)
>>
>> diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
>> index 39af03894598..af3b4b1b77eb 100644
>> --- a/net/ethernet/eth.c
>> +++ b/net/ethernet/eth.c
>> @@ -54,6 +54,7 @@
>> #include <linux/if_ether.h>
>> #include <linux/of_net.h>
>> #include <linux/pci.h>
>> +#include <linux/nvmem-consumer.h>
>> #include <net/dst.h>
>> #include <net/arp.h>
>> #include <net/sock.h>
>> @@ -527,8 +528,11 @@ unsigned char * __weak arch_get_platform_mac_address(void)
>>
>> int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
>> {
>> + unsigned char addrbuf[ETH_ALEN];
>> const unsigned char *addr;
>> + struct nvmem_cell *nvmem;
>> struct device_node *dp;
>> + size_t alen;
>>
>> if (dev_is_pci(dev))
>> dp = pci_device_to_OF_node(to_pci_dev(dev));
>> @@ -541,6 +545,29 @@ int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
>> if (!addr)
>> addr = arch_get_platform_mac_address();
>>
>> + if (!addr) {
>> + nvmem = nvmem_cell_get(dev, "mac-address");
>> + if (IS_ERR(nvmem) && PTR_ERR(nvmem) == -EPROBE_DEFER)
>> + /* We may have a lookup registered for MAC address but
>> + * the corresponding nvmem provider hasn't been
>> + * registered yet.
>> + */
>> + return -EPROBE_DEFER;
>> +
>> + if (!IS_ERR(nvmem)) {
>> + addr = nvmem_cell_read(nvmem, &alen);
>> + if (!IS_ERR(addr)) {
> ^^^^
> Never do success handling. Always error handling. Otherwise the code
> is indent a lot and the error handling is far from the call.
>
>> + if (alen == ETH_ALEN)
>> + ether_addr_copy(addrbuf, addr);
>> +
>> + kfree(addr);
>> + addr = alen == ETH_ALEN ? addrbuf : NULL;
>> + }
>> +
>> + nvmem_cell_put(nvmem);
>> + }
>> + }
>> +
>> if (!addr || !is_valid_ether_addr(addr))
> ^^^^
> Instead of handling the error we dereference the error pointer here.
>
True - we should add a check for IS_ERR(addr) here.
> *frowny face*
>
>> return -ENODEV;
>>
>> --
>
> Maybe this?
>
> if (!addr) {
> nvmem = nvmem_cell_get(dev, "mac-address");
> if (PTR_ERR(nvmem) == -EPROBE_DEFER)
> return -EPROBE_DEFER;
> if (IS_ERR(nvmem))
> return -ENODEV;
> addr = nvmem_cell_read(nvmem, &alen);
> if (IS_ERR(addr))
> return PTR_ERR(addr);
> if (alen != ETH_ALEN) {
> kfree(addr);
> return -ENODEV;
> }
> ether_addr_copy(addrbuf, addr);
> kfree(addr);
> addr = addrbuf;
> }
> if (!is_valid_ether_addr(addr))
> return -ENODEV;
> ether_addr_copy(mac_addr, addr);
> return 0;
>
I would normally go this way but here we don't want to bail out when
we encounter an error but rather continue on to the next possible
source of a MAC address. We'll get -ENODEV from nvmem_cell_get() if
the lookup fails for "mac-address" but instead of returning an error
code we should then check if we can read the MAC from MTD.
Bart
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