Re: [PATCH v2 3/3] y2038: nptl: Convert pthread_rwlock_{clock|timed}{rd|wr}lock to support 64 bit time

[Lukasz Majewski <lukma@denx.de>]

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Hi Adhemerval,

> On 19/09/2020 10:07, Lukasz Majewski wrote:
> > The pthread_rwlock_clockrdlock, pthread_rwlock_clockwrlock,
> > pthread_rwlock_timedrdlock and pthread_rwlock_timedwrlock have been
> > converted to support 64 bit time.
> > 
> > This change uses new futex_abstimed_wait64 function in
> > ./sysdeps/nptl/futex-helpers.c, which uses futex_time64 where
> > possible.
> > 
> > The pthread_rwlock_{clock|timed}{rd|wr}lock only accepts absolute
> > time. Moreover, there is no need to check for NULL passed as
> > *abstime pointer to the syscalls as those calls have exported
> > symbols marked with __nonull attribute for abstime.
> > 
> > For systems with __TIMESIZE != 64 && __WORDSIZE == 32:
> > - Conversions between 64 bit time to 32 bit are necessary
> > - Redirection to pthread_rwlock_{clock|timed}{rd|wr}lock will
> > provide support for 64 bit time
> > 
> > Build tests:
> > ./src/scripts/build-many-glibcs.py glibcs
> > 
> > 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
> > 
> > Above tests were performed with Y2038 redirection applied as well
> > as without to test the proper usage of both
> > __pthread_rwlock_{clock|timed}{rd|wr}lock64 and
> > __pthread_rwlock_{clock|timed}{rd|wr}lock.
> > 
> > Reviewed-by: Alistair Francis <alistair.francis@wdc.com>  
> 
> Looks good, there is only a issue regarding LIBC_PROBE (below).
> 
> 
> > 
> > ---
> > Changes for v2:
> > - None
> > ---
> >  nptl/pthreadP.h                   | 18 +++++++++++++++++
> >  nptl/pthread_rwlock_clockrdlock.c | 19 +++++++++++++++---
> >  nptl/pthread_rwlock_clockwrlock.c | 19 +++++++++++++++---
> >  nptl/pthread_rwlock_common.c      | 33
> > +++++++++++++++---------------- nptl/pthread_rwlock_rdlock.c      |
> >  2 +- nptl/pthread_rwlock_timedrdlock.c | 19 +++++++++++++++---
> >  nptl/pthread_rwlock_timedwrlock.c | 19 +++++++++++++++---
> >  nptl/pthread_rwlock_wrlock.c      |  2 +-
> >  8 files changed, 100 insertions(+), 31 deletions(-)
> > 
> > diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> > index 9bb44c8535..5bcc8a2db5 100644
> > --- a/nptl/pthreadP.h
> > +++ b/nptl/pthreadP.h
> > @@ -464,6 +464,10 @@ extern int __pthread_cond_wait (pthread_cond_t
> > *cond, pthread_mutex_t *mutex); # define __pthread_timedjoin_np64
> > __pthread_timedjoin_np # define __pthread_cond_timedwait64
> > __pthread_cond_timedwait # define __pthread_cond_clockwait64
> > __pthread_cond_clockwait +# define __pthread_rwlock_clockrdlock64
> > __pthread_rwlock_clockrdlock +# define
> > __pthread_rwlock_clockwrlock64 __pthread_rwlock_clockwrlock +#
> > define __pthread_rwlock_timedrdlock64 __pthread_rwlock_timedrdlock
> > +# define __pthread_rwlock_timedwrlock64
> > __pthread_rwlock_timedwrlock #else extern int
> > __pthread_clockjoin_np64 (pthread_t threadid, void **thread_return,
> > clockid_t clockid, @@ -481,6 +485,20 @@ extern int
> > __pthread_cond_clockwait64 (pthread_cond_t *cond, clockid_t clockid,
> >                                         const struct __timespec64
> > *abstime); libpthread_hidden_proto (__pthread_cond_clockwait64)
> > +extern int __pthread_rwlock_clockrdlock64 (pthread_rwlock_t
> > *rwlock,
> > +                                           clockid_t clockid,
> > +                                           const struct
> > __timespec64 *abstime); +libpthread_hidden_proto
> > (__pthread_rwlock_clockrdlock64) +extern int
> > __pthread_rwlock_clockwrlock64 (pthread_rwlock_t *rwlock,
> > +                                           clockid_t clockid,
> > +                                           const struct
> > __timespec64 *abstime); +libpthread_hidden_proto
> > (__pthread_rwlock_clockwrlock64) +extern int
> > __pthread_rwlock_timedrdlock64 (pthread_rwlock_t *rwlock,
> > +                                           const struct
> > __timespec64 *abstime); +libpthread_hidden_proto
> > (__pthread_rwlock_timedrdlock64) +extern int
> > __pthread_rwlock_timedwrlock64 (pthread_rwlock_t *rwlock,
> > +                                           const struct
> > __timespec64 *abstime); +libpthread_hidden_proto
> > (__pthread_rwlock_timedwrlock64) #endif
> >  
> >  extern int __pthread_cond_timedwait (pthread_cond_t *cond,  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_clockrdlock.c
> > b/nptl/pthread_rwlock_clockrdlock.c index 4cedfd1dcd..d93b133c9e
> > 100644 --- a/nptl/pthread_rwlock_clockrdlock.c
> > +++ b/nptl/pthread_rwlock_clockrdlock.c
> > @@ -21,8 +21,21 @@
> >  
> >  /* See pthread_rwlock_common.c.  */
> >  int
> > -pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t
> > clockid,
> > -			    const struct timespec *abstime)
> > +__pthread_rwlock_clockrdlock64 (pthread_rwlock_t *rwlock,
> > clockid_t clockid,
> > +                                const struct __timespec64 *abstime)
> >  {
> > -  return __pthread_rwlock_rdlock_full (rwlock, clockid, abstime);
> > +  return __pthread_rwlock_rdlock_full64 (rwlock, clockid, abstime);
> >  }
> > +
> > +#if __TIMESIZE != 64
> > +libpthread_hidden_def (__pthread_rwlock_clockrdlock64)  
> 
> Maybe an extra space here?

Ok. Fixed.

> 
> > +int
> > +__pthread_rwlock_clockrdlock (pthread_rwlock_t *rwlock, clockid_t
> > clockid,
> > +                              const struct timespec *abstime)
> > +{
> > +  struct __timespec64 ts64 = valid_timespec_to_timespec64
> > (*abstime); +
> > +  return __pthread_rwlock_clockrdlock64 (rwlock, clockid, &ts64);
> > +}
> > +#endif
> > +weak_alias (__pthread_rwlock_clockrdlock,
> > pthread_rwlock_clockrdlock)  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_clockwrlock.c
> > b/nptl/pthread_rwlock_clockwrlock.c index 7a954cf529..10a314c76d
> > 100644 --- a/nptl/pthread_rwlock_clockwrlock.c
> > +++ b/nptl/pthread_rwlock_clockwrlock.c
> > @@ -21,8 +21,21 @@
> >  
> >  /* See pthread_rwlock_common.c.  */
> >  int
> > -pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t
> > clockid,
> > -			    const struct timespec *abstime)
> > +__pthread_rwlock_clockwrlock64 (pthread_rwlock_t *rwlock,
> > clockid_t clockid,
> > +                                const struct __timespec64 *abstime)
> >  {
> > -  return __pthread_rwlock_wrlock_full (rwlock, clockid, abstime);
> > +  return __pthread_rwlock_wrlock_full64 (rwlock, clockid, abstime);
> >  }
> > +  
> 
> Ok.
> 
> > +#if __TIMESIZE != 64
> > +libpthread_hidden_def (__pthread_rwlock_clockwrlock64)  
> 
> Maybe an extra space here?

Ok. Fixed.

> 
> > +int
> > +__pthread_rwlock_clockwrlock (pthread_rwlock_t *rwlock, clockid_t
> > clockid,
> > +                              const struct timespec *abstime)
> > +{
> > +  struct __timespec64 ts64 = valid_timespec_to_timespec64
> > (*abstime); +
> > +  return __pthread_rwlock_clockwrlock64 (rwlock, clockid, &ts64);
> > +}
> > +#endif
> > +weak_alias (__pthread_rwlock_clockwrlock,
> > pthread_rwlock_clockwrlock)  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_common.c
> > b/nptl/pthread_rwlock_common.c index 3fbc66ded2..4c9f582d3d 100644
> > --- a/nptl/pthread_rwlock_common.c
> > +++ b/nptl/pthread_rwlock_common.c
> > @@ -278,9 +278,8 @@ __pthread_rwlock_rdunlock (pthread_rwlock_t
> > *rwlock) 
> >  
> >  static __always_inline int
> > -__pthread_rwlock_rdlock_full (pthread_rwlock_t *rwlock,
> > -    clockid_t clockid,
> > -    const struct timespec *abstime)
> > +__pthread_rwlock_rdlock_full64 (pthread_rwlock_t *rwlock,
> > clockid_t clockid,
> > +                                const struct __timespec64 *abstime)
> >  {
> >    unsigned int r;
> >    
> 
> Ok.
> 
> > @@ -330,8 +329,9 @@ __pthread_rwlock_rdlock_full (pthread_rwlock_t
> > *rwlock, & PTHREAD_RWLOCK_RWAITING) != 0)
> >  		{
> >  		  int private = __pthread_rwlock_get_private
> > (rwlock);
> > -		  int err = futex_abstimed_wait
> > (&rwlock->__data.__readers,
> > -						 r, clockid,
> > abstime, private);
> > +		  int err = __futex_abstimed_wait64
> > (&rwlock->__data.__readers,
> > +		                                     r, clockid,
> > abstime,
> > +		                                     private);
> >  		  /* We ignore EAGAIN and EINTR.  On time-outs, we
> > can just return because we don't need to clean up anything.  */
> >  		  if (err == ETIMEDOUT)  
> 
> Ok.
> 
> > @@ -457,9 +457,9 @@ __pthread_rwlock_rdlock_full (pthread_rwlock_t
> > *rwlock, (&rwlock->__data.__wrphase_futex,
> >  		   &wpf, wpf | PTHREAD_RWLOCK_FUTEX_USED)))
> >  	    continue;
> > -	  int err = futex_abstimed_wait
> > (&rwlock->__data.__wrphase_futex,
> > -					 1 |
> > PTHREAD_RWLOCK_FUTEX_USED,
> > -					 clockid, abstime,
> > private);
> > +	  int err = __futex_abstimed_wait64
> > (&rwlock->__data.__wrphase_futex,
> > +					     1 |
> > PTHREAD_RWLOCK_FUTEX_USED,
> > +					     clockid, abstime,
> > private); if (err == ETIMEDOUT)
> >  	    {
> >  	      /* If we timed out, we need to unregister.  If no
> > read phase  
> 
> Ok.
> 
> > @@ -585,9 +585,8 @@ __pthread_rwlock_wrunlock (pthread_rwlock_t
> > *rwlock) 
> >  
> >  static __always_inline int
> > -__pthread_rwlock_wrlock_full (pthread_rwlock_t *rwlock,
> > -    clockid_t clockid,
> > -    const struct timespec *abstime)
> > +__pthread_rwlock_wrlock_full64 (pthread_rwlock_t *rwlock,
> > clockid_t clockid,
> > +                                const struct __timespec64 *abstime)
> >  {
> >    /* Make sure any passed in clockid and timeout value are valid.
> > Note that the previous implementation assumed that this check
> > *must* not be @@ -728,9 +727,9 @@ __pthread_rwlock_wrlock_full
> > (pthread_rwlock_t *rwlock, share the flag, and another writer will
> > wake one of the writers in this group.  */
> >  	  may_share_futex_used_flag = true;
> > -	  int err = futex_abstimed_wait
> > (&rwlock->__data.__writers_futex,
> > -					 1 |
> > PTHREAD_RWLOCK_FUTEX_USED,
> > -					 clockid, abstime,
> > private);
> > +	  int err = __futex_abstimed_wait64
> > (&rwlock->__data.__writers_futex,
> > +					     1 |
> > PTHREAD_RWLOCK_FUTEX_USED,
> > +					     clockid, abstime,
> > private); if (err == ETIMEDOUT)
> >  	    {
> >  	      if (prefer_writer)  
> 
> Ok.
> 
> > @@ -827,9 +826,9 @@ __pthread_rwlock_wrlock_full (pthread_rwlock_t
> > *rwlock, (&rwlock->__data.__wrphase_futex, &wpf,
> >  		   PTHREAD_RWLOCK_FUTEX_USED)))
> >  	    continue;
> > -	  int err = futex_abstimed_wait
> > (&rwlock->__data.__wrphase_futex,
> > -					 PTHREAD_RWLOCK_FUTEX_USED,
> > -					 clockid, abstime,
> > private);
> > +	  int err = __futex_abstimed_wait64
> > (&rwlock->__data.__wrphase_futex,
> > +
> > PTHREAD_RWLOCK_FUTEX_USED,
> > +					     clockid, abstime,
> > private); if (err == ETIMEDOUT)
> >  	    {
> >  	      if (rwlock->__data.__flags !=
> > PTHREAD_RWLOCK_PREFER_READER_NP)  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_rdlock.c
> > b/nptl/pthread_rwlock_rdlock.c index 04cecad395..2b8509a49c 100644
> > --- a/nptl/pthread_rwlock_rdlock.c
> > +++ b/nptl/pthread_rwlock_rdlock.c
> > @@ -24,7 +24,7 @@ __pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
> >  {
> >    LIBC_PROBE (rdlock_entry, 1, rwlock);  
> 
> We need to move the systemtap probe to the 64-bit variant, so the
> 64-bit time will still trigger it.

Those are syscalls, which don't require timespec time.

The LIBC_PROBE() macros were there before, so I left them as is and
only changed __pthread_rwlock_rdlock_full() to
__pthread_rwlock_rdlock_full64().


On the other hand - for example:
__pthread_rwlock_clockwrlock() and __pthread_rwlock_clockwrlock64()
are only calling __pthread_rwlock_wrlock_full64(), and there were no
LIBC_PROBE() macros before.

Do I understand correctly that you propose to add LIBC_PROBE() macros
to e.g. __pthread_rwlock_clockwrlock64() ?

> 
> >  
> > -  int result = __pthread_rwlock_rdlock_full (rwlock,
> > CLOCK_REALTIME, NULL);
> > +  int result = __pthread_rwlock_rdlock_full64 (rwlock,
> > CLOCK_REALTIME, NULL); LIBC_PROBE (rdlock_acquire_read, 1, rwlock);
> >    return result;
> >  }  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_timedrdlock.c
> > b/nptl/pthread_rwlock_timedrdlock.c index c5d8aee909..d5999a1419
> > 100644 --- a/nptl/pthread_rwlock_timedrdlock.c
> > +++ b/nptl/pthread_rwlock_timedrdlock.c
> > @@ -20,8 +20,21 @@
> >  
> >  /* See pthread_rwlock_common.c.  */
> >  int
> > -pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
> > -    const struct timespec *abstime)
> > +__pthread_rwlock_timedrdlock64 (pthread_rwlock_t *rwlock,
> > +                                const struct __timespec64 *abstime)
> >  {
> > -  return __pthread_rwlock_rdlock_full (rwlock, CLOCK_REALTIME,
> > abstime);
> > +  return __pthread_rwlock_rdlock_full64 (rwlock, CLOCK_REALTIME,
> > abstime); }
> > +  
> 
> Ok.
> 
> > +#if __TIMESIZE != 64
> > +libpthread_hidden_def (__pthread_rwlock_timedrdlock64)  
> 
> Maybe an extra space here?

Ok. Fixed.

> 
> > +int
> > +__pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
> > +                              const struct timespec *abstime)
> > +{
> > +  struct __timespec64 ts64 = valid_timespec_to_timespec64
> > (*abstime); +
> > +  return __pthread_rwlock_timedrdlock64 (rwlock, &ts64);
> > +}
> > +#endif
> > +weak_alias (__pthread_rwlock_timedrdlock,
> > pthread_rwlock_timedrdlock)  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_timedwrlock.c
> > b/nptl/pthread_rwlock_timedwrlock.c index ccee8b77d9..6c5284a172
> > 100644 --- a/nptl/pthread_rwlock_timedwrlock.c
> > +++ b/nptl/pthread_rwlock_timedwrlock.c
> > @@ -20,8 +20,21 @@
> >  
> >  /* See pthread_rwlock_common.c.  */
> >  int
> > -pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock,
> > -    const struct timespec *abstime)
> > +__pthread_rwlock_timedwrlock64 (pthread_rwlock_t *rwlock,
> > +                                const struct __timespec64 *abstime)
> >  {
> > -  return __pthread_rwlock_wrlock_full (rwlock, CLOCK_REALTIME,
> > abstime);
> > +  return __pthread_rwlock_wrlock_full64 (rwlock, CLOCK_REALTIME,
> > abstime); }
> > +
> > +#if __TIMESIZE != 64
> > +libpthread_hidden_def (__pthread_rwlock_timedwrlock64)  
> 
> 
> Maybe an extra space here?

Ok. Fixed.

> 
> > +int
> > +__pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock,
> > +                              const struct timespec *abstime)
> > +{
> > +  struct __timespec64 ts64 = valid_timespec_to_timespec64
> > (*abstime); +
> > +  return __pthread_rwlock_timedwrlock64 (rwlock, &ts64);
> > +}
> > +#endif
> > +weak_alias (__pthread_rwlock_timedwrlock,
> > pthread_rwlock_timedwrlock)  
> 
> Ok.
> 
> > diff --git a/nptl/pthread_rwlock_wrlock.c
> > b/nptl/pthread_rwlock_wrlock.c index a42aa626f0..210e6cffdc 100644
> > --- a/nptl/pthread_rwlock_wrlock.c
> > +++ b/nptl/pthread_rwlock_wrlock.c
> > @@ -24,7 +24,7 @@ __pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
> >  {
> >    LIBC_PROBE (wrlock_entry, 1, rwlock);  
> 
> We need to move the systemtap probe to the 64-bit variant, so the
> 64-bit time will still trigger it.

The same comment as above apply here.

> 
> >  
> > -  int result = __pthread_rwlock_wrlock_full (rwlock,
> > CLOCK_REALTIME, NULL);
> > +  int result = __pthread_rwlock_wrlock_full64 (rwlock,
> > CLOCK_REALTIME, NULL); LIBC_PROBE (wrlock_acquire_write, 1, rwlock);
> >    return result;
> >  }
> >   
> 
> Ok.


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

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