Re: [PATCH v2 5/5] y2038: Replace __clock_gettime with __clock_gettime64

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

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On 04/05/2020 12:32, Lukasz Majewski wrote:
> Hi Adhemerval,
> 
>> On 01/05/2020 08:56, Lukasz Majewski wrote:
>>> Hi Adhemerval,
>>>   
>>>> On 26/03/2020 05:06, Lukasz Majewski wrote:  
>>>>> diff --git a/nis/nis_call.c b/nis/nis_call.c
>>>>> index 92c70e97aa..9c6f62a753 100644
>>>>> --- a/nis/nis_call.c
>>>>> +++ b/nis/nis_call.c
>>>>> @@ -709,7 +709,7 @@ __nisfind_server (const_nis_name name, int
>>>>> search_parent, nis_error status;
>>>>>    directory_obj *obj;
>>>>>    struct timeval now;
>>>>> -  struct timespec ts;
>>>>> +  struct __timespec64 ts;
>>>>>    unsigned int server_used = ~0;
>>>>>    unsigned int current_ep = ~0;
>>>>>  
>>>>> @@ -719,8 +719,8 @@ __nisfind_server (const_nis_name name, int
>>>>> search_parent, if (*dir != NULL)
>>>>>      return NIS_SUCCESS;
>>>>>  
>>>>> -  __clock_gettime (CLOCK_REALTIME, &ts);
>>>>> -  TIMESPEC_TO_TIMEVAL (&now, &ts);
>>>>> +  __clock_gettime64 (CLOCK_REALTIME, &ts);
>>>>> +  now = valid_timespec64_to_timeval (ts);
>>>>>  
>>>>>    if ((flags & NO_CACHE) == 0)
>>>>>      *dir = nis_server_cache_search (name, search_parent,
>>>>> &server_used,    
>>>>
>>>> I think it would be simpler to just remove the timeval argument on
>>>> nis_server_cache_search and move the __clock_gettime64 call on the
>>>> function start.   
>>>
>>> Have I understood you correctly that you recommend removing the
>>> "now" struct timeval argument and then call explicitly
>>> __clock_gettime64 on the beginning of nis_server_cache_search
>>> function?  
>>
>> Yes, the nis_server_cache_search is a static function used only once
>> at __nisfind_server.
> 
> Ok.
> 
>>
>>>   
>>>>
>>>> Also, it would require to change nis_server_cache to use a
>>>> __time64_t for 'expires', otherwise this change won't help in
>>>> case of a time_t overflow.
>>>>  
>>>
>>> Ok. I will update this. Thanks for pointing this out.
>>>   
>>>>  
>>>>> diff --git a/sysdeps/generic/hp-timing.h
>>>>> b/sysdeps/generic/hp-timing.h index e2d7447212..af9d92f7f7 100644
>>>>> --- a/sysdeps/generic/hp-timing.h
>>>>> +++ b/sysdeps/generic/hp-timing.h
>>>>> @@ -34,8 +34,8 @@ typedef uint64_t hp_timing_t;
>>>>>     vDSO symbol.  */
>>>>>  #define HP_TIMING_NOW(var) \
>>>>>  ({
>>>>> 	\
>>>>> -  struct timespec tv;
>>>>> 	\
>>>>> -  __clock_gettime (CLOCK_MONOTONIC, &tv);
>>>>> \
>>>>> +  struct __timespec64 tv;
>>>>> 	\
>>>>> +  __clock_gettime64 (CLOCK_MONOTONIC, &tv);
>>>>> \ (var) = (tv.tv_nsec + UINT64_C(1000000000) * tv.tv_sec);
>>>>> \ })
>>>>>      
>>>>
>>>> Ok.
>>>>  
>>>>> diff --git a/sysdeps/generic/memusage.h
>>>>> b/sysdeps/generic/memusage.h index a111864b0b..91e56d24de 100644
>>>>> --- a/sysdeps/generic/memusage.h
>>>>> +++ b/sysdeps/generic/memusage.h
>>>>> @@ -28,9 +28,9 @@
>>>>>  #ifndef GETTIME
>>>>>  # define GETTIME(low,high)
>>>>> 	   \ {
>>>>> 			   \
>>>>> -    struct timespec now;
>>>>> 	   \
>>>>> +    struct __timespec64 now;
>>>>> 		   \ uint64_t usecs;
>>>>> 			   \
>>>>> -    clock_gettime (CLOCK_REALTIME, &now);
>>>>> 	   \
>>>>> +    __clock_gettime64 (CLOCK_REALTIME, &now);
>>>>> 		   \ usecs = (uint64_t)now.tv_nsec / 1000 +
>>>>> (uint64_t)now.tv_sec * 1000000; \ low = usecs & 0xffffffff;
>>>>> 					   \ high = usecs >>
>>>>> 32;							   \
>>>>>  
>>>>
>>>> Is is the requirement to export __clock_gettime64 as a
>>>> GLIBC_PRIVATE symbol?
>>>>  
>>>
>>> The __clock_gettime is already exported as GLIBC_PRIVATE at
>>> ./time/Versions, so I'm following this pattern.
>>>
>>> Moreover, the glibc will not build when __clock_gettime64 is not
>>> exported.
>>>   
>>>> In any case, I think we should try to avoid use internal symbols
>>>> even for distributed glibc libraries, so I think this change
>>>> should go once we start to export the clock_gettime64 as default
>>>> symbol.  
>>>
>>> Am I correct that this is a preprocessor macro, which is in the
>>> exported header?  
>>
>> In fact __clock_gettime is used on other internal libraries and it
>> is required as is to avoid linknamespace pollution.  So it seems
>> that __clock_gettime64 should follow the same logic.
> 
> Ok, So then __clock_gettime64 shall be exported as well.
> 
>>
>> It might be misleading that for some ABI __clock_gettime and
>> for other __clock_gettime64 will be used internally, but it should
>> be ok nonetheless.
>>
> 
> All the occurrences of __clock_gettime shall be replaced by
> __clock_gettime64 internally in glibc as __clock_gettime64 is Y2038
> safe for e.g. ARM32 and is aliased to __clock_gettime for 64 bit archs
> anyway.

I meant that some architectures does not provide __clock_gettime64 and
thus the internal symbol will be __clock_gettime. But it is not an
issue in fact.


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