On 17-04-25 12:04 PM, Jiri Pirko wrote:
Tue, Apr 25, 2017 at 03:01:22PM CEST, j...@mojatatu.com wrote:
On 17-04-25 08:13 AM, Jiri Pirko wrote:
Tue, Apr 25, 2017 at 01:54:06PM CEST, j...@mojatatu.com wrote:
+static inline bool tca_flags_valid(u32 act_flags)
+{
+ u32 invalid_flags_mask = ~VALID_TCA_FLAGS;
+
+ if (act_flags & invalid_flags_mask)
+ return false;
I don't see how this resolves anything. VALID_TCA_FLAGS is set in stone
not going to change anytime in future, right?
Every time a new bit gets added VALID_TCA_FLAGS changes.
You mean flag that user can set? If that is the case, you are breaking
UAPI for newer app running on older kernel.
Ok, let me try to explain with more clarity. The rules Iam
trying to follow are:
if i see any bit set that i dont understand I will reject.
So lets in first kernel I have support for bit 0.
My validation check is to make sure only bit 0 is set.
The valid_flags currently then only constitutes bit 0.
i.e
If you set bit 2 or 3, the function above will reject and i return
the error to the user.
That is expected behavior correct?
3 months down the road:
I add two flags - bit 1 and 2.
So now my valid_flags changes to bits 1, 2 and 0.
The function above will now return true for bits 0-2 but
will reject if you set bit 3.
That is expected behavior, correct?
On u32/16/8:
I am choosing u32 so it allows me to add more upto 32 bit flags.
Not all 32 are needed today but it is better insurance.
If I used u8 then the 24 of those 32 bits i dont use will be used
as pads in the TLV. So it doesnt make sense for me to use a u8/16.
Does that make more sense?
cheers,
jamal
