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Re: RFC: out-of-tree tty driver breakage (changing ASYNC_ bits)

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  Re: RFC: out-of-tree tty driver breakage (changing ASYNC_ bits) Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-28 17:50 +0200
    Re: RFC: out-of-tree tty driver breakage (changing ASYNC_ bits) Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-28 18:00 +0200
      Re: RFC: out-of-tree tty driver breakage (changing ASYNC_ bits) Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-28 18:10 +0200

#1433079 — Re: RFC: out-of-tree tty driver breakage (changing ASYNC_ bits)

On 2016-01-11, Peter Hurley <peter@hurleysoftware.com> wrote:
> On 01/11/2016 07:53 AM, Grant Edwards wrote:
>> On 2016-01-11, Greg KH <gregkh@linuxfoundation.org> wrote:
>>> On Sun, Jan 10, 2016 at 01:42:44PM -0800, Peter Hurley wrote:
>>>
>>>> This will break out-of-tree drivers but I don't really see a
>>>> realistic alternative. Also, I think the new symbol prefix ASY_ isn't
>>>> great and I'd like to get some suggestions.
>>>
>>> Don't worry about breaking out-of-tree drivers, that's fine.
>> 
>> One request from this maintainer of several out-of-tree drivers: if
>> you break something, break it such that it won't compile.  It would be
>> nice to avoid changes that break functionality but still compile
>> without warning.
>
> I was in the process of writing how I can't remove
> ASYNC_INITIALIZED, et.al from the uapi header, when I realized that
> I can just guard them with #ifndef _KERNEL_ which will trigger the
> requisite out-of-tree build break.

One of my drivers checks that state of port.flags & ASYNC_INITIALIZED
in various places (it also checks some other port.flags bits
(_CLOSING, _SPD_xxxx, _LOW_LATENCY).

I've been regulary building against linux-next waiting for the build
to fail when the flag changes got pulled.  It still builds cleanly,
but it looks like the flags canges are indeed in linux-next.

Does that mean that I don't need to change my code to use
tty_port_initialized()?

You know that _KERNEL_ is defined when when compiling kernel-space
code (either in-tree or out-of-tree), right?

I see from comments in tty_flags.h that ASYNC_CLOSING is no longer
used.  But I don't see a replacement in tty.h

-- 
Grant Edwards               grant.b.edwards        Yow! I'm having a
                                  at               tax-deductible experience!
                              gmail.com            I need an energy crunch!!

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#1433082

On 2016-06-28, Grant Edwards <grant.b.edwards@gmail.com> wrote:
> On 2016-01-11, Peter Hurley <peter@hurleysoftware.com> wrote:
>> On 01/11/2016 07:53 AM, Grant Edwards wrote:
>>> On 2016-01-11, Greg KH <gregkh@linuxfoundation.org> wrote:
>>>> On Sun, Jan 10, 2016 at 01:42:44PM -0800, Peter Hurley wrote:
>>>>
>>>>> This will break out-of-tree drivers but I don't really see a
>>>>> realistic alternative. Also, I think the new symbol prefix ASY_ isn't
>>>>> great and I'd like to get some suggestions.
>>>>
>>>> Don't worry about breaking out-of-tree drivers, that's fine.
>>> 
>>> One request from this maintainer of several out-of-tree drivers: if
>>> you break something, break it such that it won't compile.  It would be
>>> nice to avoid changes that break functionality but still compile
>>> without warning.
>>
>> I was in the process of writing how I can't remove
>> ASYNC_INITIALIZED, et.al from the uapi header, when I realized that
>> I can just guard them with #ifndef _KERNEL_ which will trigger the
>> requisite out-of-tree build break.

> You know that _KERNEL_ is defined when when compiling kernel-space
> code (either in-tree or out-of-tree), right?

Ignore that.  I missed the 'n' in #ifndef.  My driver build should
fail due to ASYNC_INITIALIZED being undefined, but it isn't.  :/

For some reason _KERNEL_ is not defined when my module is being
compiled....

-- 
Grant Edwards               grant.b.edwards        Yow! JAPAN is a WONDERFUL
                                  at               planet -- I wonder if we'll
                              gmail.com            ever reach their level of
                                                   COMPARATIVE SHOPPING ...

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#1433090

On 2016-06-28, Grant Edwards <grant.b.edwards@gmail.com> wrote:
> On 2016-06-28, Grant Edwards <grant.b.edwards@gmail.com> wrote:
>> On 2016-01-11, Peter Hurley <peter@hurleysoftware.com> wrote:
>>> On 01/11/2016 07:53 AM, Grant Edwards wrote:
>>>> On 2016-01-11, Greg KH <gregkh@linuxfoundation.org> wrote:
>>>>> On Sun, Jan 10, 2016 at 01:42:44PM -0800, Peter Hurley wrote:
>>>>>
>>>>>> This will break out-of-tree drivers but I don't really see a
>>>>>> realistic alternative. Also, I think the new symbol prefix ASY_ isn't
>>>>>> great and I'd like to get some suggestions.
>>>>>
>>>>> Don't worry about breaking out-of-tree drivers, that's fine.
>>>> 
>>>> One request from this maintainer of several out-of-tree drivers: if
>>>> you break something, break it such that it won't compile.  It would be
>>>> nice to avoid changes that break functionality but still compile
>>>> without warning.
>>>
>>> I was in the process of writing how I can't remove
>>> ASYNC_INITIALIZED, et.al from the uapi header, when I realized that
>>> I can just guard them with #ifndef _KERNEL_ which will trigger the
>>> requisite out-of-tree build break.
>
>> You know that _KERNEL_ is defined when when compiling kernel-space
>> code (either in-tree or out-of-tree), right?
>
> Ignore that.  I missed the 'n' in #ifndef.  My driver build should
> fail due to ASYNC_INITIALIZED being undefined, but it isn't.  :/
>
> For some reason _KERNEL_ is not defined when my module is being
> compiled....

That's because it's __KERNEL__ not _KERNEL_ that get's defined when
compiling kernel-space code.  So, in tty_flags.h:

    81  #define ASYNC_SPD_MASK          (ASYNC_SPD_HI|ASYNC_SPD_VHI|ASYNC_SPD_SHI)
    82  
    83  #ifndef _KERNEL_
    84  /* These flags are no longer used (and were always masked from userspace) */
    85  #define ASYNC_INITIALIZED       (1U << ASYNCB_INITIALIZED)
    86  #define ASYNC_NORMAL_ACTIVE     (1U << ASYNCB_NORMAL_ACTIVE)

Shoulnd't line 83 be 

        #ifndef __KERNEL__
?

-- 
Grant Edwards               grant.b.edwards        Yow! PARDON me, am I
                                  at               speaking ENGLISH?
                              gmail.com            

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