Re: [PATCH 3/3] Add runtime check for __ASSUME_REQUEUE_PI (BZ#18463)

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

Ping.

On 24/05/2016 16:07, Adhemerval Zanella wrote:
> I am sending a new version of this patch because now prio_inherit_missing
> is non longer static inline function, its name causes namespace pollution.
> Main change from previous version is just the new name scheme by prepending
> a double underscore.
> 
> --
> 
> Tested on ARM (v3.8 kernel) and x86_64.
> 
> 	* nptl/pthreadP.h (prio_inherit_missing): Change name to
> 	__prio_inherit_missing.
> 	(USE_REQUEUE_PI): Remove define.
> 	(use_requeue_pi): New function.
> 	* nptl/pthread_cond_broadcast.c [__ASSUME_REQUEUE_PI]
> 	(__pthread_cond_broadcast): Remove ifdef.
> 	(USE_REQUEUE_PI): Change to use_requeue_pi.
> 	* nptl/pthread_cond_signal.c [__ASSUME_REQUEUE_PI]
> 	(__pthread_cond_signal): Remove ifdef.
> 	(USE_REQUEUE_PI): Change to use_requeue_pi.
> 	* nptl/pthread_cond_timedwait.c [__ASSUME_REQUEUE_PI]
> 	(__pthread_cond_timedwait): Remove ifdef.
> 	(USE_REQUEUE_PI): Change to use_requeue_pi.
> 	( nptl/pthread_cond_wait.c [__ASSUME_REQUEUE_PI]
> 	(__pthread_cond_wait): Remove ifdef.
> 	(USE_REQUEUE_PI): Change to use_requeue_pi.
> 	* nptl/pthread_mutex_init.c (prio_inherit_missing): Remove 'static'
> 	qualifier and change name to __prio_inherit_missing.
> ---
>  nptl/pthreadP.h               | 23 ++++++++++++++---------
>  nptl/pthread_cond_broadcast.c |  5 ++---
>  nptl/pthread_cond_signal.c    |  5 ++---
>  nptl/pthread_cond_timedwait.c | 11 ++++-------
>  nptl/pthread_cond_wait.c      | 13 +++++--------
>  nptl/pthread_mutex_init.c     |  7 ++++---
>  7 files changed, 50 insertions(+), 33 deletions(-)
> 
> diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
> index d479a3e..e53f649 100644
> --- a/nptl/pthreadP.h
> +++ b/nptl/pthreadP.h
> @@ -585,17 +585,22 @@ extern void __wait_lookup_done (void) attribute_hidden;
>  # define PTHREAD_STATIC_FN_REQUIRE(name) __asm (".globl " #name);
>  #endif
>  
> +extern bool prio_inherit_missing (void);
> +
>  /* Test if the mutex is suitable for the FUTEX_WAIT_REQUEUE_PI operation.  */
> -#if (defined lll_futex_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> -# define USE_REQUEUE_PI(mut) \
> -   ((mut) && (mut) != (void *) ~0l \
> -    && (((mut)->__data.__kind \
> -	 & (PTHREAD_MUTEX_PRIO_INHERIT_NP | PTHREAD_MUTEX_ROBUST_NORMAL_NP)) \
> -	== PTHREAD_MUTEX_PRIO_INHERIT_NP))
> -#else
> -# define USE_REQUEUE_PI(mut) 0
> +static inline bool
> +use_requeue_pi (pthread_mutex_t *mut)
> +{
> +#ifndef __ASSUME_REQUEUE_PI
> +  if (__prio_inherit_missing ())
> +    return false;
>  #endif
> +  return (mut) &&
> +    (mut) != (void *) ~0l &&
> +    (((mut)->__data.__kind
> +      & (PTHREAD_MUTEX_PRIO_INHERIT_NP | PTHREAD_MUTEX_ROBUST_NORMAL_NP)) ==
> +     PTHREAD_MUTEX_PRIO_INHERIT_NP);
> +}
>  
>  /* Returns 0 if POL is a valid scheduling policy.  */
>  static inline int
> diff --git a/nptl/pthread_cond_broadcast.c b/nptl/pthread_cond_broadcast.c
> index 552fd42..ef81bcd 100644
> --- a/nptl/pthread_cond_broadcast.c
> +++ b/nptl/pthread_cond_broadcast.c
> @@ -60,9 +60,8 @@ __pthread_cond_broadcast (pthread_cond_t *cond)
>  	  || PTHREAD_MUTEX_PSHARED (mut) & PTHREAD_MUTEX_PSHARED_BIT)
>  	goto wake_all;
>  
> -#if (defined lll_futex_cmp_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> -      if (USE_REQUEUE_PI (mut))
> +#ifdef lll_futex_cmp_requeue_pi
> +      if (use_requeue_pi (mut))
>  	{
>  	  if (lll_futex_cmp_requeue_pi (&cond->__data.__futex, 1, INT_MAX,
>  					&mut->__data.__lock, futex_val,
> diff --git a/nptl/pthread_cond_signal.c b/nptl/pthread_cond_signal.c
> index b3a6d3d..9c8f883 100644
> --- a/nptl/pthread_cond_signal.c
> +++ b/nptl/pthread_cond_signal.c
> @@ -46,11 +46,10 @@ __pthread_cond_signal (pthread_cond_t *cond)
>        ++cond->__data.__wakeup_seq;
>        ++cond->__data.__futex;
>  
> -#if (defined lll_futex_cmp_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_cmp_requeue_pi
>        pthread_mutex_t *mut = cond->__data.__mutex;
>  
> -      if (USE_REQUEUE_PI (mut)
> +      if (use_requeue_pi (mut)
>  	/* This can only really fail with a ENOSYS, since nobody can modify
>  	   futex while we have the cond_lock.  */
>  	  && lll_futex_cmp_requeue_pi (&cond->__data.__futex, 1, 0,
> diff --git a/nptl/pthread_cond_timedwait.c b/nptl/pthread_cond_timedwait.c
> index 711a51d..61a651c 100644
> --- a/nptl/pthread_cond_timedwait.c
> +++ b/nptl/pthread_cond_timedwait.c
> @@ -63,8 +63,7 @@ __pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
>    int pshared = (cond->__data.__mutex == (void *) ~0l)
>  		? LLL_SHARED : LLL_PRIVATE;
>  
> -#if (defined lll_futex_timed_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_timed_wait_requeue_pi
>    int pi_flag = 0;
>  #endif
>  
> @@ -161,8 +160,7 @@ __pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
>  
>  /* REQUEUE_PI was implemented after FUTEX_CLOCK_REALTIME, so it is sufficient
>     to check just the former.  */
> -#if (defined lll_futex_timed_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_timed_wait_requeue_pi
>        /* If pi_flag remained 1 then it means that we had the lock and the mutex
>  	 but a spurious waker raced ahead of us.  Give back the mutex before
>  	 going into wait again.  */
> @@ -171,7 +169,7 @@ __pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
>  	  __pthread_mutex_cond_lock_adjust (mutex);
>  	  __pthread_mutex_unlock_usercnt (mutex, 0);
>  	}
> -      pi_flag = USE_REQUEUE_PI (mutex);
> +      pi_flag = use_requeue_pi (mutex);
>  
>        if (pi_flag)
>  	{
> @@ -250,8 +248,7 @@ __pthread_cond_timedwait (pthread_cond_t *cond, pthread_mutex_t *mutex,
>    __pthread_cleanup_pop (&buffer, 0);
>  
>    /* Get the mutex before returning.  */
> -#if (defined lll_futex_timed_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_timed_wait_requeue_pi
>    if (pi_flag)
>      {
>        __pthread_mutex_cond_lock_adjust (mutex);
> diff --git a/nptl/pthread_cond_wait.c b/nptl/pthread_cond_wait.c
> index 3f62acc..f79bf67 100644
> --- a/nptl/pthread_cond_wait.c
> +++ b/nptl/pthread_cond_wait.c
> @@ -86,7 +86,7 @@ __condvar_cleanup (void *arg)
>  
>    /* Get the mutex before returning unless asynchronous cancellation
>       is in effect.  We don't try to get the mutex if we already own it.  */
> -  if (!(USE_REQUEUE_PI (cbuffer->mutex))
> +  if (!(use_requeue_pi (cbuffer->mutex))
>        || ((cbuffer->mutex->__data.__lock & FUTEX_TID_MASK)
>  	  != THREAD_GETMEM (THREAD_SELF, tid)))
>    {
> @@ -106,8 +106,7 @@ __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
>    int pshared = (cond->__data.__mutex == (void *) ~0l)
>  		? LLL_SHARED : LLL_PRIVATE;
>  
> -#if (defined lll_futex_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_wait_requeue_pi
>    int pi_flag = 0;
>  #endif
>  
> @@ -160,8 +159,7 @@ __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
>        /* Enable asynchronous cancellation.  Required by the standard.  */
>        cbuffer.oldtype = __pthread_enable_asynccancel ();
>  
> -#if (defined lll_futex_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_wait_requeue_pi
>        /* If pi_flag remained 1 then it means that we had the lock and the mutex
>  	 but a spurious waker raced ahead of us.  Give back the mutex before
>  	 going into wait again.  */
> @@ -170,7 +168,7 @@ __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
>  	  __pthread_mutex_cond_lock_adjust (mutex);
>  	  __pthread_mutex_unlock_usercnt (mutex, 0);
>  	}
> -      pi_flag = USE_REQUEUE_PI (mutex);
> +      pi_flag = use_requeue_pi (mutex);
>  
>        if (pi_flag)
>  	{
> @@ -221,8 +219,7 @@ __pthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
>    __pthread_cleanup_pop (&buffer, 0);
>  
>    /* Get the mutex before returning.  Not needed for PI.  */
> -#if (defined lll_futex_wait_requeue_pi \
> -     && defined __ASSUME_REQUEUE_PI)
> +#ifdef lll_futex_wait_requeue_pi
>    if (pi_flag)
>      {
>        __pthread_mutex_cond_lock_adjust (mutex);
> diff --git a/nptl/pthread_mutex_init.c b/nptl/pthread_mutex_init.c
> index 6aef890..c37f623 100644
> --- a/nptl/pthread_mutex_init.c
> +++ b/nptl/pthread_mutex_init.c
> @@ -33,8 +33,9 @@ static const struct pthread_mutexattr default_mutexattr =
>    };
>  
>  
> -static bool
> -prio_inherit_missing (void)
> +bool
> +attribute_hidden
> +__prio_inherit_missing (void)
>  {
>  #ifdef __NR_futex
>    static int tpi_supported;
> @@ -72,7 +73,7 @@ __pthread_mutex_init (pthread_mutex_t *mutex,
>        break;
>  
>      case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
> -      if (__glibc_unlikely (prio_inherit_missing ()))
> +      if (__glibc_unlikely (__prio_inherit_missing ()))
>  	return ENOTSUP;
>        break;
>  
>