Re: [PATCH 2/9] [compat-2.6 and compat-stable] Remove unused code

[Hauke Mehrtens <hauke@hauke-m.de>]

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Hin-Tak Leung wrote:
> On Mon, Oct 12, 2009 at 10:19 PM, Hauke Mehrtens <hauke@hauke-m.de> wrote:
>> LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28) can not be true in
>> compat-2.6.28.h. The definitions are not needed in compat-wireless any
>> more. Removing this does not break compiling with mainline kernel 2.6.25
>> to 2.6.32
> 
> Hmm, I am not questioning your decision for removing unused code, but
> if they are genuinely unused, why were they introduced in the first
> place?

I have added them in edcf845e4bd65d00132f02237bee3fd3daca318f but I can
not find any references to them in compat-wireless. For me it looks like
it was a mistake to introduce them. The commit comment does not say
anything about it (my bad) and I forgot why I added it.

> As a side comment, while it is unusual (compared to the usual <
> version_X), it is a possible scenario for compat-X.h to have codes
> that conditions on LINUX_VERSION_CODE >= version_X - and if memory
> serves the bits you are removing were added only recently; and they
> looks like what they are (i.e. public kernel symbols became
> private-static during 2.6.27<->2.6.28 or the other way round).

The condition #if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28)) was
added recently because without it openSuse with kernel 2.6.27 will not
compile. OpenSuse backports the tracepoint part into their 2.6.27 kernel.

> I guess I am looking for a reason why they were added in the first
> place, if they serve no purpose.
>
>> Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
>> ---
>>  compat/compat-2.6.28.h |   24 ------------------------
>>  1 files changed, 0 insertions(+), 24 deletions(-)
>>
>> diff --git a/compat/compat-2.6.28.h b/compat/compat-2.6.28.h
>> index 90d080c..dd223c6 100644
>> --- a/compat/compat-2.6.28.h
>> +++ b/compat/compat-2.6.28.h
>> @@ -146,22 +146,6 @@ static inline void skb_queue_splice_tail_init(struct sk_buff_head *list,
>>        }
>>  } /* From include/linux/skbuff.h */
>>
>> -struct module;
>> -struct tracepoint;
>> -
>> -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28))
>> -struct tracepoint {
>> -       const char *name;               /* Tracepoint name */
>> -       int state;                      /* State. */
>> -       void **funcs;
>> -} __attribute__((aligned(32)));                /*
>> -                                        * Aligned on 32 bytes because it is
>> -                                        * globally visible and gcc happily
>> -                                        * align these on the structure size.
>> -                                        * Keep in sync with vmlinux.lds.h.
>> -                                        */
>> -#endif
>> -
>>  #ifndef DECLARE_TRACE
>>
>>  #define TP_PROTO(args...)      args
>> @@ -181,17 +165,9 @@ struct tracepoint {
>>                return -ENOSYS;                                         \
>>        }
>>
>> -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28))
>> -#define DEFINE_TRACE(name)
>> -#endif
>>  #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
>>  #define EXPORT_TRACEPOINT_SYMBOL(name)
>>
>> -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,28))
>> -static inline void tracepoint_update_probe_range(struct tracepoint *begin,
>> -       struct tracepoint *end)
>> -{ }
>> -#endif
>>
>>  #endif
>>
>> --
>> 1.6.2.1



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