Re: [PATCH v3 7/7] y2038: linux: Provide ___gettimeofday64 implementation

[Lukasz Majewski <lukma at denx dot de>]

Hi Adhemerval,

> > >  #else /* USE_IFUNC_GETTIMEOFDAY  */
> > > -# include <time/gettimeofday.c>
> > > +/* Conversion of gettimeofday function to support 64 bit time on
> > > archs
> > > +   with __WORDSIZE == 32 and __TIMESIZE == 32/64  */
> > > +#include <errno.h>
> > > +
> > > +int
> > > +___gettimeofday64 (struct __timeval64 *restrict tv, void
> > > *restrict tz) +{
> > > +  if (__glibc_unlikely (tz != 0))
> > > +    memset (tz, 0, sizeof (struct timezone));
> > > +
> > > +  struct __timespec64 ts64;
> > > +  int ret = __clock_gettime64 (CLOCK_REALTIME, &ts64);
> > > +
> > > +  if (ret == 0 && tv)
> > > +    *tv = timespec64_to_timeval64 (ts64);    
> > 
> > No implicit checks.  Also, we already set 'tv' with nonull
> > attribute, so I am not sure if it is worth to add an extra check
> > for 'tv' validity (specially because users tend to expect low
> > latency for the symbol).
> > 
> > In any case, if the idea is to add such check as QoI I think it
> > would be better to do a early bail before actually issue
> > __clock_gettime64.  
> 
> No, this was just my mistake. There was a discussion with Paul and
> Joseph earlier. We shall _only_ check for NULL when it is required by
> syscalls/command documentation. This is the case for e.g. setitimer's
> *old_value pointer.

I've double check this and in the documentation/manual [1] for
gettimeofday there is a sentence:

----8<--------
If either tv or tz is NULL, the corresponding structure is not set or
returned. (However, compilation warnings will result if tv is NULL.) 
---->8--------

That was the rationale to add the check
if (ret == 0 && tv)


I also think that the code as is now is correct - it returns the result
of getting the time from Linux, but it is not updating the tv structure.


Links:

[1] - https://linux.die.net/man/2/gettimeofday


Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

Attachment: pgp4Azk5xDWGR.pgp
Description: OpenPGP digital signature