Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
On Thu, Oct 13, 2016 at 09:43:57AM -0600, David Ahern wrote:
> On 10/13/16 1:16 AM, Cyrill Gorcunov wrote:
> > On Wed, Oct 12, 2016 at 07:55:04PM -0400, David Miller wrote:
> >> From: Cyrill Gorcunov
> >> Date: Wed, 12 Oct 2016 09:53:29 +0300
> >>
> >>> I can't rename the field, neither a can use union.
> >>
> >> Remind me again what is wrong with using an anonymous union?
> >
> > Anon union would be a preferred but Eric pointed me that even
> > though it might cause problems (https://patchwork.kernel.org/patch/9353365/)
> >
> > | Note that some programs could fail to compile with the added union
> > | anyway.
> > |
> > | Some gcc versions are unable to compile a static init with an union
> > |
> > | struct inet_diag_req_v2 foo = { .pad = 0, sdiag_family = AF_INET, };
> > |
> > | When I cooked my recent fq commit I simply removed a pad and replaced
> > | it :
> > |
> > | git show fefa569a9d4bc4 -- include
> >
>
> That commit suggests it is acceptable to just rename the
> pad field, which is the simplest approach.
No. In further message Eric points that
| This is a bit different of course, since struct tc_fq_qd_stats is only
| one way : Kernel produces the content and gives it to user space.
and we are simply lucky that we didn't break anything in userspace yet.
IOW, it's not a problem for me simply to
- rename it or,
- use anonymous union
but both options have own problems :/
Also I just thought what if we introduce
struct inet_diag_req_raw_v2 {
__u8sdiag_family;
__u8sdiag_protocol;
__u8idiag_ext;
__u8sdiag_raw_protocol;
__u32 idiag_states;
struct inet_diag_sockid id;
};
where @sdiag_raw_protocol explicitly stated and
will collide with existing struct inet_diag_req_v2?
This is a hack too of course but at least this
won't break api definitely.
Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
On 10/13/16 1:16 AM, Cyrill Gorcunov wrote:
> On Wed, Oct 12, 2016 at 07:55:04PM -0400, David Miller wrote:
>> From: Cyrill Gorcunov
>> Date: Wed, 12 Oct 2016 09:53:29 +0300
>>
>>> I can't rename the field, neither a can use union.
>>
>> Remind me again what is wrong with using an anonymous union?
>
> Anon union would be a preferred but Eric pointed me that even
> though it might cause problems (https://patchwork.kernel.org/patch/9353365/)
>
> | Note that some programs could fail to compile with the added union
> | anyway.
> |
> | Some gcc versions are unable to compile a static init with an union
> |
> | struct inet_diag_req_v2 foo = { .pad = 0, sdiag_family = AF_INET, };
> |
> | When I cooked my recent fq commit I simply removed a pad and replaced
> | it :
> |
> | git show fefa569a9d4bc4 -- include
>
That commit suggests it is acceptable to just rename the pad field, which is
the simplest approach.
Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
On Wed, Oct 12, 2016 at 07:55:04PM -0400, David Miller wrote:
> From: Cyrill Gorcunov
> Date: Wed, 12 Oct 2016 09:53:29 +0300
>
> > I can't rename the field, neither a can use union.
>
> Remind me again what is wrong with using an anonymous union?
Anon union would be a preferred but Eric pointed me that even
though it might cause problems (https://patchwork.kernel.org/patch/9353365/)
| Note that some programs could fail to compile with the added union
| anyway.
|
| Some gcc versions are unable to compile a static init with an union
|
| struct inet_diag_req_v2 foo = { .pad = 0, sdiag_family = AF_INET, };
|
| When I cooked my recent fq commit I simply removed a pad and replaced
| it :
|
| git show fefa569a9d4bc4 -- include
Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
From: Cyrill Gorcunov Date: Wed, 12 Oct 2016 09:53:29 +0300 > I can't rename the field, neither a can use union. Remind me again what is wrong with using an anonymous union?
Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
On Wed, Oct 12, 2016 at 01:50:22AM -0400, David Miller wrote: > > Macros that look like function calls and are also lvalues tend to be > troublesome. > > I know what you're trying to achieve, you want a named way to access > this so that the intent and semantics are clear. > > But I'd rather you do something that provides a way by which normal > struct member accesses do the job, and your earlier patches achieved > this. I can't rename the field, neither a can use union. The only acceptable option I think is introduce inet_diag_v3 structure, which of course will require the mode wide patching. If there no objections I could try to implement it.
Re: [PATCH v6] net: ip, diag -- Add diag interface for raw sockets
From: Cyrill Gorcunov Date: Thu, 6 Oct 2016 13:00:55 +0300 > v6: > - use sdiag_raw_protocol() helper which will access @pad >structure used for raw sockets protocol specification: >we can't simply rename this member without breaking uapi. Macros that look like function calls and are also lvalues tend to be troublesome. I know what you're trying to achieve, you want a named way to access this so that the intent and semantics are clear. But I'd rather you do something that provides a way by which normal struct member accesses do the job, and your earlier patches achieved this.
