Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx> [2019-05-03 11:44:54]: Hi Sergei, > > diff --git a/drivers/of/of_net.c b/drivers/of/of_net.c > > index d820f3e..258ceb8 100644 > > --- a/drivers/of/of_net.c > > +++ b/drivers/of/of_net.c > [...] > > @@ -64,6 +113,9 @@ static const void *of_get_mac_addr(struct device_node *np, const char *name) > > * addresses. Some older U-Boots only initialized 'local-mac-address'. In > > * this case, the real MAC is in 'local-mac-address', and 'mac-address' exists > > * but is all zeros. > > + * > > + * Return: Will be a valid pointer on success, NULL in case there wasn't > > + * 'mac-address' nvmem cell node found, and ERR_PTR in case of error. > > Returning both NULL and error codes on failure is usually a sign of a > misdesigned API. well, then there's a lot of misdesigned APIs in the tree already, as I've just grepped for IS_ERR_OR_NULL usage and found this pointer/NULL/ERR_PTR usage pretty legit. > Why not always return an error code? I've received following comment[1] from Andrew: "What you have to be careful of, is the return value from your new code looking in NVMEM. It should only return EPROBE_DEFER, or another error if there really is expected to be a value in NVMEM, or getting it from NVMEM resulted in an error." So in order to fullfil this remark, I can't simply use ENOENT instead of current NULL, as the caller couldn't distinguish between ENOENT from of_get_mac_address or ENOENT from NVMEM subsystem. 1. https://patchwork.ozlabs.org/patch/1092243/#2161764 -- ynezz
