Re: [PATCH 4/5] y2038: linux: Provide __timer_gettime64 implementation

[Lukasz Majewski <lukma at denx dot de>]

Hi Adhemerval,

Thank you for your review. I'm making those pointed out minor
adjustments, re-test the code and pull to master.

> On 11/11/2019 18:47, Lukasz Majewski wrote:
> > This patch provides new __timer_gettime64 explicit 64 bit function
> > for reading status of specified timer. To be more precise - the
> > remaining time and interval set with timer_settime.
> > Moreover, a 32 bit version - __timer_gettime has been refactored to
> > internally use __timer_gettime64.
> > 
> > The __timer_gettime is now supposed to be used on systems still
> > supporting 32 bit time (__TIMESIZE != 64) - hence the necessary
> > conversion from 64 bit struct __timespec64 to struct timespec.
> > 
> > The new __timer_gettime64 syscall available from Linux 5.1+ has
> > been used, when applicable.
> > 
> > Build tests:
> > - The code has been tested on x86_64/x86 (native compilation):
> > make PARALLELMFLAGS="-j8" && make check PARALLELMFLAGS="-j8" && \\
> > make xcheck PARALLELMFLAGS="-j8"
> > 
> > - The glibc has been build tested (make PARALLELMFLAGS="-j8") for
> > x86 (i386), x86_64-x32, and armv7
> > 
> > Run-time tests:
> > - Run specific tests on ARM/x86 32bit systems (qemu):
> >   https://github.com/lmajewski/meta-y2038 and run tests:
> >   https://github.com/lmajewski/y2038-tests/commits/master  
> 
> Does it have any additional coverage not present in glibc tests? If
> yes, would be possible to enhance glibc tests?

Those tests are for 32 bit archs (ARM, x86, x86-x32, RISC-V) with set
-D_TIME_BITS=64 during the compilation (to check if the system is Y2038
safe).

As glibc is not yet supporting this flag, I don't add them to glibc's
tests.

I do plan to add them when we make "the big switch" and instantly add
-D_TIME_BITS64 support to glibc.

In the meanwhile I do rely on current glibc's setup to catch
regressions when I convert functions eligible for Y2038 enhancement
(which do support __ASSUME_TIME64_SYSCALLS flag).

> 
> > 
> > - Use of cross-test-ssh.sh for ARM (armv7):
> >   make PARALLELMFLAGS="-j8" test-wrapper='./cross-test-ssh.sh
> > root@192.168.7.2' xcheck
> > 
> > Linux kernel, headers and minimal kernel version for glibc build
> > test matrix:
> > - Linux v5.1 (with timer_gettime64) and glibc build with v5.1 as
> >   minimal kernel version (--enable-kernel="5.1.0")
> >   The __ASSUME_TIME64_SYSCALLS flag defined.
> > 
> > - Linux v5.1 and default minimal kernel version
> >   The __ASSUME_TIME64_SYSCALLS not defined, but kernel supports
> > timer_gettime64 syscall.
> > 
> > - Linux v4.19 (no timer_gettime64 support) with default minimal
> > kernel version for contemporary glibc (3.2.0)
> >   This kernel doesn't support timer_gettime64 syscall, so the
> > fallback to timer_gettime is tested.
> > 
> > Above tests were performed with Y2038 redirection applied as well
> > as without (so the __TIMESIZE != 64 execution path is checked as
> > well).
> > 
> > No regressions were observed.  
> 
> LGTM with some changes below.
> 
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> 
> > ---
> >  include/time.h                          |  7 ++++
> >  sysdeps/unix/sysv/linux/timer_gettime.c | 44
> > ++++++++++++++++++++++--- 2 files changed, 47 insertions(+), 4
> > deletions(-)
> > 
> > diff --git a/include/time.h b/include/time.h
> > index 52ee213669..8b9a4b7a60 100644
> > --- a/include/time.h
> > +++ b/include/time.h
> > @@ -179,6 +179,13 @@ extern int __futimens64 (int fd, const struct
> > __timespec64 tsp[2]); libc_hidden_proto (__futimens64);
> >  #endif
> >  
> > +#if __TIMESIZE == 64
> > +# define __timer_gettime64 __timer_gettime
> > +#else
> > +extern int __timer_gettime64 (timer_t timerid, struct
> > __itimerspec64 *value); +libc_hidden_proto (__timer_gettime64);
> > +#endif
> > +
> >  /* Compute the `struct tm' representation of T,
> >     offset OFFSET seconds east of UTC,
> >     and store year, yday, mon, mday, wday, hour, min, sec into *TP.
> >  
> 
> Ok, it follows current practice.
> 
> > diff --git a/sysdeps/unix/sysv/linux/timer_gettime.c
> > b/sysdeps/unix/sysv/linux/timer_gettime.c index
> > 8d9bef9196..31bf5ce25b 100644 ---
> > a/sysdeps/unix/sysv/linux/timer_gettime.c +++
> > b/sysdeps/unix/sysv/linux/timer_gettime.c @@ -20,15 +20,51 @@
> >  #include <stdlib.h>
> >  #include <time.h>
> >  #include <sysdep.h>
> > +#include <kernel-features.h>
> >  #include "kernel-posix-timers.h"
> >  
> >  int
> > -timer_gettime (timer_t timerid, struct itimerspec *value)
> > +__timer_gettime64 (timer_t timerid, struct __itimerspec64 *value)
> >  {
> >    struct timer *kt = (struct timer *) timerid;
> >  
> > -  /* Delete the kernel timer object.  */
> > -  int res = INLINE_SYSCALL (timer_gettime, 2, kt->ktimerid, value);
> > +#ifdef __ASSUME_TIME64_SYSCALLS
> > +# ifndef __NR_timer_gettime64
> > +#  define __NR_timer_gettime64 __NR_timer_gettime
> > +# endif
> > +  return INLINE_SYSCALL (timer_gettime64, 2, kt->ktimerid, value);
> >  
> 
> Use INLINE_SYSCALL_CALL.
> 
> > +#else
> > +# ifdef __NR_timer_gettime64
> > +  int ret = INLINE_SYSCALL (timer_gettime64, 2, kt->ktimerid,
> > value);  
> 
> Ditto.
> 
> > +  if (ret == 0 || errno != ENOSYS)
> > +    return ret;
> > +# endif
> > +  struct itimerspec its32;
> > +  int retval = INLINE_SYSCALL (timer_gettime, 2, kt->ktimerid,
> > &its32);  
> 
> Ditto.
> 
> > +  if (! retval)  
> 
> Please use an explicit comparison with == 0.
> 
> > +    {
> > +      value->it_interval = valid_timespec_to_timespec64
> > (its32.it_interval);
> > +      value->it_value = valid_timespec_to_timespec64
> > (its32.it_value);
> > +    }
> >  
> > -  return res;
> > +  return retval;
> > +#endif
> >  }
> > +  
> 
> Ok.
> 
> > +#if __TIMESIZE != 64
> > +int
> > +__timer_gettime (timer_t timerid, struct itimerspec *value)
> > +{
> > +  struct __itimerspec64 its64;
> > +  int retval = __timer_gettime64 (timerid, &its64);
> > +  if (! retval)  
> 
> Please use an explicit comparison with == 0.
> 
> > +    {
> > +      value->it_interval = valid_timespec64_to_timespec
> > (its64.it_interval);
> > +      value->it_value = valid_timespec64_to_timespec
> > (its64.it_value);
> > +    }
> > +
> > +  return retval;
> > +}
> > +#endif
> > +weak_alias (__timer_gettime, timer_gettime)
> > +libc_hidden_def (timer_gettime)
> >   
> 
> Ok.




Best regards,

Lukasz Majewski

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