Re: [PATCH v2 12/13] nptl: Return EINVAL for pthread_mutex_clocklock/PI with CLOCK_MONOTONIC [BZ #26801]

[Lukasz Majewski <lukma@denx.de>]

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Hi Adhemerval,

> Changes from previous version:
> 
>   - Replace ENOTSUP by EINVAL
> 
> --
> 
> Linux futex FUTEX_LOCK_PI operation only supports CLOCK_REALTIME,
> so pthread_mutex_clocklock operation with priority aware mutexes
> may fail depending of the input timeout.
> 
> Also, it is not possible to convert a CLOCK_MONOTONIC to a
> CLOCK_REALTIME due the possible wall clock time change which might
> invalid the requested timeout.
> 
> Checked on x86_64-linux-gnu and i686-linux-gnu.
> ---
>  nptl/Makefile                  |  2 +-
>  nptl/pthread_mutex_timedlock.c |  7 ++++
>  nptl/tst-mutexpi10.c           | 68
> ++++++++++++++++++++++++++++++++++ sysdeps/pthread/tst-mutex5.c   |
> 2 + sysdeps/pthread/tst-mutex9.c   |  2 +
>  5 files changed, 80 insertions(+), 1 deletion(-)
>  create mode 100644 nptl/tst-mutexpi10.c
> 
> diff --git a/nptl/Makefile b/nptl/Makefile
> index 968768d33b..a48426a396 100644
> --- a/nptl/Makefile
> +++ b/nptl/Makefile
> @@ -265,7 +265,7 @@ tests = tst-attr2 tst-attr3 tst-default-attr \
>  	tst-mutex5a tst-mutex7a \
>  	tst-mutexpi1 tst-mutexpi2 tst-mutexpi3 tst-mutexpi4 \
>  	tst-mutexpi5 tst-mutexpi5a tst-mutexpi6 tst-mutexpi7
> tst-mutexpi7a \
> -	tst-mutexpi9 \
> +	tst-mutexpi9 tst-mutexpi10 \
>  	tst-cond22 tst-cond26 \
>  	tst-robustpi1 tst-robustpi2 tst-robustpi3 tst-robustpi4
> tst-robustpi5 \ tst-robustpi6 tst-robustpi7 tst-robustpi9 \
> diff --git a/nptl/pthread_mutex_timedlock.c
> b/nptl/pthread_mutex_timedlock.c index b42862193a..aaaafa21ce 100644
> --- a/nptl/pthread_mutex_timedlock.c
> +++ b/nptl/pthread_mutex_timedlock.c
> @@ -313,6 +313,13 @@ __pthread_mutex_clocklock_common
> (pthread_mutex_t *mutex, case PTHREAD_MUTEX_PI_ROBUST_NORMAL_NP:
>      case PTHREAD_MUTEX_PI_ROBUST_ADAPTIVE_NP:
>        {
> +	/* Currently futex FUTEX_LOCK_PI operation only provides
> support for
> +	   CLOCK_REALTIME and trying to emulate by converting a
> +	   CLOCK_MONOTONIC to CLOCK_REALTIME will take in account
> possible
> +	   changes to the wall clock.  */
> +	if (__glibc_unlikely (clockid != CLOCK_REALTIME))
> +	  return EINVAL;
> +
>  	int kind, robust;
>  	{
>  	  /* See concurrency notes regarding __kind in struct
> __pthread_mutex_s diff --git a/nptl/tst-mutexpi10.c
> b/nptl/tst-mutexpi10.c new file mode 100644
> index 0000000000..84ba1dfa97
> --- /dev/null
> +++ b/nptl/tst-mutexpi10.c
> @@ -0,0 +1,68 @@
> +/* Check if pthread_mutex_clocklock with PRIO_INHERIT fails with
> clock
> +   different than CLOCK_REALTIME.
> +   Copyright (C) 2015-2020 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
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <pthread.h>
> +#include <errno.h>
> +#include <array_length.h>
> +
> +#include <support/check.h>
> +#include <support/xthread.h>
> +#include <support/timespec.h>
> +
> +static int
> +do_test (void)
> +{
> +  const int types[] = {
> +    PTHREAD_MUTEX_NORMAL,
> +    PTHREAD_MUTEX_ERRORCHECK,
> +    PTHREAD_MUTEX_RECURSIVE,
> +    PTHREAD_MUTEX_ADAPTIVE_NP
> +  };
> +  const int robust[] = {
> +    PTHREAD_MUTEX_STALLED,
> +    PTHREAD_MUTEX_ROBUST
> +  };
> +
> +
> +  for (int t = 0; t < array_length (types); t++)
> +    for (int r = 0; r < array_length (robust); r++)
> +      {
> +	pthread_mutexattr_t attr;
> +
> +	xpthread_mutexattr_init (&attr);
> +	xpthread_mutexattr_setprotocol (&attr, PTHREAD_PRIO_INHERIT);
> +	xpthread_mutexattr_settype (&attr, types[t]);
> +	xpthread_mutexattr_setrobust (&attr, robust[r]);
> +
> +	pthread_mutex_t mtx;
> +	xpthread_mutex_init (&mtx, &attr);
> +
> +	struct timespec tmo = timespec_add (xclock_now
> (CLOCK_MONOTONIC),
> +					    make_timespec (0,
> 100000000)); +
> +	TEST_COMPARE (pthread_mutex_clocklock (&mtx,
> CLOCK_MONOTONIC, &tmo),
> +		      EINVAL);
> +
> +	xpthread_mutex_destroy (&mtx);
> +      }
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/sysdeps/pthread/tst-mutex5.c
> b/sysdeps/pthread/tst-mutex5.c index 14490768c3..bfe1a79fa4 100644
> --- a/sysdeps/pthread/tst-mutex5.c
> +++ b/sysdeps/pthread/tst-mutex5.c
> @@ -112,7 +112,9 @@ static int do_test (void)
>  {
>    do_test_clock (CLOCK_USE_TIMEDLOCK, "timedlock");
>    do_test_clock (CLOCK_REALTIME, "clocklock(realtime)");
> +#ifndef ENABLE_PI
>    do_test_clock (CLOCK_MONOTONIC, "clocklock(monotonic)");
> +#endif
>    return 0;
>  }
>  
> diff --git a/sysdeps/pthread/tst-mutex9.c
> b/sysdeps/pthread/tst-mutex9.c index 2d7927b7c2..bfc01f8c75 100644
> --- a/sysdeps/pthread/tst-mutex9.c
> +++ b/sysdeps/pthread/tst-mutex9.c
> @@ -133,7 +133,9 @@ do_test (void)
>  {
>    do_test_clock (CLOCK_USE_TIMEDLOCK);
>    do_test_clock (CLOCK_REALTIME);
> +#ifndef ENABLE_PI
>    do_test_clock (CLOCK_MONOTONIC);
> +#endif
>    return 0;
>  }
>  

Reviewed-by: Lukasz Majewski <lukma@denx.de>


Best regards,

Lukasz Majewski

--

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