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

[Lukasz Majewski <lukma@denx.de>]

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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.


Best regards,

Lukasz Majewski

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