Re: [PATCH v3 7/8] linux: Use long time_t for wait4/getrusage

[Alistair Francis <alistair23@gmail.com>]

On Sat, Feb 15, 2020 at 8:27 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> Hi Alistair,
>
> > The Linux kernel expects rusage to use a 32-bit time_t, even on archs
> > with a 64-bit time_t (like RV32). To address this let's convert
> > rusage to/from 32-bit and 64-bit to ensure the kernel always gets
> > a 32-bit time_t.
> >
> > While we are converting these functions let's also convert them to be
> > the y2038 safe versions. This means there is a *64 function that is
> > called by a backwards compatible wrapper.
> > ---
> >  include/sys/resource.h                | 10 +++++
> >  sysdeps/unix/sysv/linux/getrusage.c   | 58
> > +++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/tv32-compat.h |
> > 47 ++++++++++++++++++++++ sysdeps/unix/sysv/linux/wait4.c       | 49
> > +++++++++++++++++++++- 4 files changed, 162 insertions(+), 2
> > deletions(-) create mode 100644 sysdeps/unix/sysv/linux/getrusage.c
> >
> > diff --git a/include/sys/resource.h b/include/sys/resource.h
> > index 9d604dfe3e..1a530fb62d 100644
> > --- a/include/sys/resource.h
> > +++ b/include/sys/resource.h
> > @@ -134,5 +134,15 @@ extern int __getrusage (enum __rusage_who __who,
> > struct rusage *__usage) extern int __setrlimit (enum
> > __rlimit_resource __resource, const struct rlimit *__rlimits);
> >  libc_hidden_proto (__setrlimit);
> > +
> > +#if __TIMESIZE == 64
> > +# define __getrusage64 __getrusage
> > +# define __wait4_time64 __wait4
> > +#else
> > +extern int __getrusage64 (enum __rusage_who who, struct __rusage64
> > *usage); +libc_hidden_proto (__getrusage64)
> > +pid_t __wait4_time64 (pid_t pid, int *stat_loc, int options, struct
> > __rusage64 *usage); +libc_hidden_proto (__wait4_time64)
>
> Please add extern on the beginning. Moreover, the declaration is longer
> than 80 chars.
>
> > +#endif
> >  #endif
> >  #endif
> > diff --git a/sysdeps/unix/sysv/linux/getrusage.c
> > b/sysdeps/unix/sysv/linux/getrusage.c new file mode 100644
> > index 0000000000..a4e382ed53
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/getrusage.c
> > @@ -0,0 +1,58 @@
> > +/* getrusage -- get the rusage struct.  Linux version.
> > +   Copyright (C) 2020 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be
> > useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <sys/time.h>
> > +#include <sys/resource.h>
> > +#include <sys/types.h>
> > +#include <sysdep.h>
> > +#include <tv32-compat.h>
> > +
> > +int
> > +__getrusage64 (enum __rusage_who who, struct __rusage64 *usage)
> > +{
> > +#if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> > +  return INLINE_SYSCALL_CALL (getrusage, who, usage);
> > +#else
> > +  struct __rusage32 usage32;
> > +  if (INLINE_SYSCALL_CALL (getrusage, who, &usage32) == -1)
> > +    return -1;
> > +
> > +  rusage32_to_rusage64 (&usage32, usage);
> > +  return 0;
> > +#endif
> > +}
> > +
> > +#if __TIMESIZE != 64
> > +libc_hidden_def (__getrusage64)
> > +int
> > +__getrusage (enum __rusage_who who, struct rusage *usage)
> > +{
> > +  int ret ;
> > +  struct __rusage64 usage64;
> > +
> > +  ret = __getrusage64 (who, &usage64);
> > +
> > +  if (ret != 0)
> > +    return ret;
> > +
> > +  rusage64_to_rusage (&usage64, usage);
> > +
> > +  return ret;
> > +}
> > +#endif
> > +weak_alias (__getrusage, getrusage)
> > diff --git a/sysdeps/unix/sysv/linux/tv32-compat.h
> > b/sysdeps/unix/sysv/linux/tv32-compat.h index 4eb6f216ea..c2231f042f
> > 100644 --- a/sysdeps/unix/sysv/linux/tv32-compat.h
> > +++ b/sysdeps/unix/sysv/linux/tv32-compat.h
> > @@ -24,6 +24,7 @@
> >  #include <bits/types.h>
> >  #include <bits/types/time_t.h>
> >  #include <bits/types/struct_timeval.h>
> > +#include <sys/resource.h>
> >
> >  /* Structures containing 'struct timeval' with 32-bit time_t.  */
> >  struct __itimerval32
> > @@ -32,4 +33,50 @@ struct __itimerval32
> >    struct __timeval32 it_value;
> >  };
> >
> > +struct __rusage32
> > +{
> > +  struct __timeval32 ru_utime;       /* user time used */
> > +  struct __timeval32 ru_stime;       /* system time used */
> > +  long ru_maxrss;            /* maximum resident set size */
> > +  long ru_ixrss;             /* integral shared memory size */
> > +  long ru_idrss;             /* integral unshared data size */
> > +  long ru_isrss;             /* integral unshared stack size */
> > +  long ru_minflt;            /* page reclaims */
> > +  long ru_majflt;            /* page faults */
> > +  long ru_nswap;             /* swaps */
> > +  long ru_inblock;           /* block input operations */
> > +  long ru_oublock;           /* block output operations */
> > +  long ru_msgsnd;            /* messages sent */
> > +  long ru_msgrcv;            /* messages received */
> > +  long ru_nsignals;          /* signals received */
> > +  long ru_nvcsw;             /* voluntary context switches */
> > +  long ru_nivcsw;            /* involuntary " */
> > +};
> > +
> > +static inline void
> > +rusage32_to_rusage64 (const struct __rusage32 *restrict r32,
> > +                    struct __rusage64 *restrict r64)
> > +{
> > +  /* Make sure the entire output structure is cleared, including
> > +     padding and reserved fields.  */
> > +  memset (r64, 0, sizeof *r64);
> > +
> > +  r64->ru_utime    = valid_timeval32_to_timeval64 (r32->ru_utime);
> > +  r64->ru_stime    = valid_timeval32_to_timeval64 (r32->ru_stime);
> > +  r64->ru_maxrss   = r32->ru_maxrss;
> > +  r64->ru_ixrss    = r32->ru_ixrss;
> > +  r64->ru_idrss    = r32->ru_idrss;
> > +  r64->ru_isrss    = r32->ru_isrss;
> > +  r64->ru_minflt   = r32->ru_minflt;
> > +  r64->ru_majflt   = r32->ru_majflt;
> > +  r64->ru_nswap    = r32->ru_nswap;
> > +  r64->ru_inblock  = r32->ru_inblock;
> > +  r64->ru_oublock  = r32->ru_oublock;
> > +  r64->ru_msgsnd   = r32->ru_msgsnd;
> > +  r64->ru_msgrcv   = r32->ru_msgrcv;
> > +  r64->ru_nsignals = r32->ru_nsignals;
> > +  r64->ru_nvcsw    = r32->ru_nvcsw;
> > +  r64->ru_nivcsw   = r32->ru_nivcsw;
> > +}
> > +
> >  #endif /* tv32-compat.h */
> > diff --git a/sysdeps/unix/sysv/linux/wait4.c
> > b/sysdeps/unix/sysv/linux/wait4.c index 3a8bed1169..f4df1c3b99 100644
> > --- a/sysdeps/unix/sysv/linux/wait4.c
> > +++ b/sysdeps/unix/sysv/linux/wait4.c
> > @@ -18,14 +18,30 @@
> >
> >  #include <sys/wait.h>
> >  #include <sys/resource.h>
> > +#include <sys/types.h>
> >  #include <sysdep-cancel.h>
> > +#include <tv32-compat.h>
> >
> >  pid_t
> > -__wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
> > +__wait4_time64 (pid_t pid, int *stat_loc, int options, struct
> > __rusage64 *usage) {
> >  #ifdef __NR_wait4
> > +# if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> >    return SYSCALL_CANCEL (wait4, pid, stat_loc, options, usage);
> > +# else
> > +  struct __rusage32 usage32;
> > +  pid_t ret = SYSCALL_CANCEL (wait4, pid, stat_loc, options,
> > &usage32); +
> > +  if (ret != 0)
> > +    return ret;
> > +
> > +  if (usage != NULL)
> > +      rusage32_to_rusage64 (&usage32, usage);
> > +
> > +  return ret;
> > +# endif
> >  #elif defined (__ASSUME_WAITID_PID0_P_PGID)
> > +  struct __rusage32 usage32;
> >    idtype_t idtype = P_PID;
> >
> >    if (pid < -1)
> > @@ -41,7 +57,12 @@ __wait4 (pid_t pid, int *stat_loc, int options,
> > struct rusage *usage) options |= WEXITED;
> >
> >    siginfo_t infop;
> > +
> > +# if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> >    if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options, usage) <
> > 0) +# else
> > +  if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options,
> > &usage32) < 0) +# endif
> >      return -1;
> >
> >    if (stat_loc)
> > @@ -70,8 +91,13 @@ __wait4 (pid_t pid, int *stat_loc, int options,
> > struct rusage *usage) }
> >      }
> >
> > +# if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64 == 0
> > +  if (usage != NULL)
> > +      rusage32_to_rusage64 (&usage32, usage);
> > +# endif
> > +
> >    return infop.si_pid;
> > -# else
> > +#else
> >  /* Linux waitid prior kernel 5.4 does not support waiting for the
> > current process.  It is possible to emulate wait4 it by calling
> > getpgid for PID 0, however, it would require an additional syscall
> > and it is inherent @@ -81,5 +107,24 @@ __wait4 (pid_t pid, int
> > *stat_loc, int options, struct rusage *usage) # error "The kernel ABI
> > does not provide a way to implement wait4" #endif
> >  }
> > +libc_hidden_def (__wait4_time64)
> > +
> > +#if __TIMESIZE != 64
>
> I think that the above libc_hidden_def (__wait4_time64) shall be moved
> here (after #if __TIMESIZE != 64)
>
> > +pid_t
> > +__wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
> > +{
> > +  pid_t ret ;
> > +  struct __rusage64 usage64;
> > +
> > +  ret = __wait4_time64 (pid, stat_loc, options, &usage64);
> > +
> > +  if (ret != 0)
> > +    return ret;
> > +
> > +  rusage64_to_rusage (&usage64, usage);
> > +
> > +  return ret;
> > +}
> >  libc_hidden_def (__wait4);
> > +#endif
>
> The above libc_hidden_def (__wait4); shall be moved here.
>
> >  weak_alias (__wait4, wait4)

Thanks for the review. I have made all of the requested changes.

Alistair

>
>
>
>
> 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