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glibc  2.9
Functions | Variables
pthread_mutex_init.c File Reference
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <kernel-features.h>
#include "pthreadP.h"

Go to the source code of this file.

Functions

int __pthread_mutex_init (pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexattr)

Variables

static struct pthread_mutexattr
static int tpi_supported

Function Documentation

Definition at line 40 of file pthread_mutex_init.c.

{
  const struct pthread_mutexattr *imutexattr;

  assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T);

  imutexattr = (const struct pthread_mutexattr *) mutexattr ?: &default_attr;

  /* Sanity checks.  */
  switch (__builtin_expect (imutexattr->mutexkind
                         & PTHREAD_MUTEXATTR_PROTOCOL_MASK,
                         PTHREAD_PRIO_NONE
                         << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
    {
    case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
      break;

    case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
#ifndef __ASSUME_FUTEX_LOCK_PI
      if (__builtin_expect (tpi_supported == 0, 0))
       {
         int lock = 0;
         INTERNAL_SYSCALL_DECL (err);
         int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI,
                                  0, 0);
         assert (INTERNAL_SYSCALL_ERROR_P (ret, err));
         tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1;
       }
      if (__builtin_expect (tpi_supported < 0, 0))
       return ENOTSUP;
#endif
      break;

    default:
      /* XXX: For now we don't support robust priority protected mutexes.  */
      if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST)
       return ENOTSUP;
      break;
    }

  /* Clear the whole variable.  */
  memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);

  /* Copy the values from the attribute.  */
  mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;

  if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
    {
#ifndef __ASSUME_SET_ROBUST_LIST
      if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
         && __set_robust_list_avail < 0)
       return ENOTSUP;
#endif

      mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
    }

  switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
    {
    case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
      mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP;
      break;

    case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
      mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP;

      int ceiling = (imutexattr->mutexkind
                   & PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
                  >> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT;
      if (! ceiling)
       {
         if (__sched_fifo_min_prio == -1)
           __init_sched_fifo_prio ();
         if (ceiling < __sched_fifo_min_prio)
           ceiling = __sched_fifo_min_prio;
       }
      mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
      break;

    default:
      break;
    }

  /* The kernel when waking robust mutexes on exit never uses
     FUTEX_PRIVATE_FLAG FUTEX_WAKE.  */
  if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED
                            | PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0)
    mutex->__data.__kind |= PTHREAD_MUTEX_PSHARED_BIT;

  /* Default values: mutex not used yet.  */
  // mutex->__count = 0;    already done by memset
  // mutex->__owner = 0;    already done by memset
  // mutex->__nusers = 0;   already done by memset
  // mutex->__spins = 0;    already done by memset
  // mutex->__next = NULL;  already done by memset

  return 0;
}

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Variable Documentation

struct pthread_mutexattr [static]
Initial value:
  {
    
    .mutexkind = PTHREAD_MUTEX_NORMAL
  }

Definition at line 27 of file pthread_mutex_init.c.

int tpi_supported [static]

Definition at line 35 of file pthread_mutex_init.c.