Re: [PATCH 8/8] staging: rtl8188eu: use is_broadcast_ether_addr
From: Michael Straube
Date: Mon Jul 30 2018 - 13:14:16 EST
On 07/29/18 22:05, Joe Perches wrote:
On Sun, 2018-07-29 at 20:21 +0200, Michael Straube wrote:
On 07/29/18 19:59, Joe Perches wrote:
On Sun, 2018-07-29 at 19:42 +0200, Michael Straube wrote:
On 07/29/18 19:21, Joe Perches wrote:
On Sun, 2018-07-29 at 19:08 +0200, Michael Straube wrote:
Use is_broadcast_ether_addr instead of checking each byte of the
address array for 0xff. Shortens the code and improves readability.
You should show in the commit log that sta_addr is __aligned(2)
as required by is_broadcast_ether_addr, otherwise you could be
introducing runtime alignment defects.
Ok, sta_addr is used from following structs.
struct ieee_param {
u32 cmd;
u8 sta_addr[ETH_ALEN];
union {
...
...
}; u
};
struct ieee_param_ex {
u32 cmd;
u8 sta_addr[ETH_ALEN];
u8 data[0];
};
Well, looking at it now, I'm not sure about the alignment anymore
in the struct that contains the union. Is sta_addr in the first
struct __aligned(2)?
Should I include the snippets in the commit message, or is just
writing that sta_addr is __aligned(2) enough? (if it is in the
first case...)
It's enough to just state that the uses are properly aligned
as long as you looked and understand that it's required.
Ok, thank you.
I looked at it and understand that it's required.
But, as mentioned, at second look I'm not sure about the union.
I guess I need to read a little more about the alignment of unions.
Any hints are welcomed. :)
The union doesn't matter here.
Only the locations of sta_addr matter.
Both follow a u32, so they are also aligned to a u32.
That is actually not guaranteed by the c standard
as the u8 array could have arbitrary padding bytes
inserted between the u32, but no compiler used by
the kernel does that.
Ah ok, thank you.
Michael