1  /* Internal definitions for pthreads library.
       2     Copyright (C) 2016-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library;  if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _PT_MUTEX_H
      20  #define _PT_MUTEX_H	1
      21  
      22  /* Special ID used to signal an unrecoverable robust mutex. */
      23  #define NOTRECOVERABLE_ID   (1U << 31)
      24  
      25  /* Common path for robust mutexes. Assumes the variable 'ret'
      26   * is bound in the function this is called from. */
      27  #define ROBUST_LOCK(self, mtxp, cb, ...)   \
      28    if (mtxp->__owner_id == NOTRECOVERABLE_ID)   \
      29      return ENOTRECOVERABLE;   \
      30    else if (mtxp->__owner_id == self->thread   \
      31  	   && __getpid () == (int)(mtxp->__lock & LLL_OWNER_MASK))   \
      32      {   \
      33        if (mtxp->__type == PT_MTX_RECURSIVE)   \
      34          {   \
      35            if (__glibc_unlikely (mtxp->__cnt + 1 == 0))   \
      36              return EAGAIN;   \
      37            \
      38            ++mtxp->__cnt;   \
      39            return 0;   \
      40          }   \
      41        else if (mtxp->__type == PT_MTX_ERRORCHECK)   \
      42          return EDEADLK;   \
      43      }   \
      44    \
      45    ret = cb (mtxp->__lock, ##__VA_ARGS__);   \
      46    if (ret == 0 || ret == EOWNERDEAD)   \
      47      {   \
      48        if (mtxp->__owner_id == ENOTRECOVERABLE)   \
      49          ret = ENOTRECOVERABLE;   \
      50        else   \
      51          {   \
      52            mtxp->__owner_id = self->thread;   \
      53            mtxp->__cnt = 1;   \
      54            if (ret == EOWNERDEAD)   \
      55              {   \
      56                mtxp->__lock = mtxp->__lock | LLL_DEAD_OWNER;   \
      57                atomic_write_barrier ();   \
      58              }   \
      59          }   \
      60      }   \
      61    (void)0
      62  
      63  /* Check that a thread owns the mutex. For non-robust, task-shared
      64   * objects, we have to check the thread *and* process-id. */
      65  #define mtx_owned_p(mtx, pt, flags)   \
      66    ((mtx)->__owner_id == (pt)->thread   \
      67     && (((flags) & GSYNC_SHARED) == 0   \
      68         || (mtx)->__shpid == __getpid ()))
      69  
      70  /* Record a thread as the owner of the mutex. */
      71  #define mtx_set_owner(mtx, pt, flags)   \
      72    (void)   \
      73      ({   \
      74         (mtx)->__owner_id = (pt)->thread;   \
      75         if ((flags) & GSYNC_SHARED)   \
      76           (mtx)->__shpid = __getpid ();   \
      77       })
      78  
      79  /* Redefined mutex types. The +1 is for binary compatibility. */
      80  #define PT_MTX_NORMAL       __PTHREAD_MUTEX_TIMED
      81  #define PT_MTX_RECURSIVE    (__PTHREAD_MUTEX_RECURSIVE + 1)
      82  #define PT_MTX_ERRORCHECK   (__PTHREAD_MUTEX_ERRORCHECK + 1)
      83  
      84  /* Mutex type, including robustness. */
      85  #define MTX_TYPE(mtxp)   \
      86    ((mtxp)->__type | ((mtxp)->__flags & PTHREAD_MUTEX_ROBUST))
      87  
      88  extern int __getpid (void) __attribute__ ((const));
      89  
      90  #endif /* pt-mutex.h */