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Differences between /sos/ksynch.c (Article 8) and /sos/ksynch.c (Article 6.5)

 /* Copyright (C) 2004 David Decotigny              /* Copyright (C) 2004 David Decotigny
                                                    
    This program is free software; you can redi        This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU Genera        modify it under the terms of the GNU General Public License
    as published by the Free Software Foundatio        as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any lat        of the License, or (at your option) any later version.
                                                       
    This program is distributed in the hope tha        This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the         but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details        GNU General Public License for more details.
                                                       
    You should have received a copy of the GNU         You should have received a copy of the GNU General Public License
    along with this program; if not, write to t        along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 3        Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA.                                               USA. 
 */                                                 */
                                                    
                                                    
 #include <hwcore/irq.h>                            #include <hwcore/irq.h>
                                                    
                                                    
 #include "ksynch.h"                                #include "ksynch.h"
                                                    
                                                    
 sos_ret_t sos_ksema_init(struct sos_ksema *sem     sos_ret_t sos_ksema_init(struct sos_ksema *sema, const char *name,
                          int initial_value,    !!                           int initial_value)
                          sos_kwaitq_ordering_t << 
 {                                                  {
   sema->value = initial_value;                       sema->value = initial_value;
   return sos_kwaitq_init(& sema->kwaitq, name, !!    return sos_kwaitq_init(& sema->kwaitq, name);
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_ksema_dispose(struct sos_ksema *     sos_ret_t sos_ksema_dispose(struct sos_ksema *sema)
 {                                                  {
   return sos_kwaitq_dispose(& sema->kwaitq);         return sos_kwaitq_dispose(& sema->kwaitq);
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_ksema_down(struct sos_ksema *sem     sos_ret_t sos_ksema_down(struct sos_ksema *sema,
                          struct sos_time *time                              struct sos_time *timeout)
 {                                                  {
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t retval;                                  sos_ret_t retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
   retval = SOS_OK;                                   retval = SOS_OK;
                                                    
   sema->value --;                                    sema->value --;
   if (sema->value < 0)                               if (sema->value < 0)
     {                                                  {
       /* Wait for somebody to wake us */                 /* Wait for somebody to wake us */
       retval = sos_kwaitq_wait(& sema->kwaitq,           retval = sos_kwaitq_wait(& sema->kwaitq, timeout);
                                                    
       /* Something wrong happened (timeout, ex           /* Something wrong happened (timeout, external wakeup, ...) ? */
       if (SOS_OK != retval)                              if (SOS_OK != retval)
         {                                                  {
           /* Yes: pretend we did not ask for t               /* Yes: pretend we did not ask for the semaphore */
           sema->value ++;                                    sema->value ++;
         }                                                  }
     }                                                  }
                                                    
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_ksema_trydown(struct sos_ksema *     sos_ret_t sos_ksema_trydown(struct sos_ksema *sema)
 {                                                  {
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t retval;                                  sos_ret_t retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
                                                    
   /* Can we take the semaphore without blockin       /* Can we take the semaphore without blocking ? */
   if (sema->value >= 1)                              if (sema->value >= 1)
     {                                                  {
       /* Yes: we take it now */                          /* Yes: we take it now */
       sema->value --;                                    sema->value --;      
       retval = SOS_OK;                                   retval = SOS_OK;
     }                                                  }
   else                                               else
     {                                                  {
       /* No: we signal it */                             /* No: we signal it */
       retval = -SOS_EBUSY;                               retval = -SOS_EBUSY;
     }                                                  }
                                                    
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_ksema_up(struct sos_ksema *sema)     sos_ret_t sos_ksema_up(struct sos_ksema *sema)
 {                                                  {
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t retval;                                  sos_ret_t retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
                                                    
   sema->value ++;                                    sema->value ++;
   retval = sos_kwaitq_wakeup(& sema->kwaitq, 1       retval = sos_kwaitq_wakeup(& sema->kwaitq, 1, SOS_OK);
                                                    
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_kmutex_init(struct sos_kmutex *m !!  sos_ret_t sos_kmutex_init(struct sos_kmutex *mutex, const char *name)
                           sos_kwaitq_ordering_ << 
 {                                                  {
   mutex->owner = NULL;                               mutex->owner = NULL;
   return sos_kwaitq_init(& mutex->kwaitq, name !!    return sos_kwaitq_init(& mutex->kwaitq, name);
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_kmutex_dispose(struct sos_kmutex     sos_ret_t sos_kmutex_dispose(struct sos_kmutex *mutex)
 {                                                  {
   return sos_kwaitq_dispose(& mutex->kwaitq);        return sos_kwaitq_dispose(& mutex->kwaitq);
 }                                                  }
                                                    
                                                    
 /*                                                 /*
  * Implementation based on ownership transfer       * Implementation based on ownership transfer (ie no while()
  * loop). The only assumption is that the thre      * loop). The only assumption is that the thread awoken by
  * kmutex_unlock is not suppressed before effe      * kmutex_unlock is not suppressed before effectively waking up: in
  * that case the mutex will be forever locked       * that case the mutex will be forever locked AND unlockable (by
  * nobody other than the owner, but this is no      * nobody other than the owner, but this is not natural since this
  * owner already issued an unlock()...). The s      * owner already issued an unlock()...). The same problem happens with
  * the semaphores, but in a less obvious manne      * the semaphores, but in a less obvious manner.
  */                                                 */
 sos_ret_t sos_kmutex_lock(struct sos_kmutex *m     sos_ret_t sos_kmutex_lock(struct sos_kmutex *mutex,
                           struct sos_time *tim                               struct sos_time *timeout)
 {                                                  {
   __label__ exit_kmutex_lock;                        __label__ exit_kmutex_lock;
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t retval;                                  sos_ret_t retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
   retval = SOS_OK;                                   retval = SOS_OK;
                                                    
   /* Mutex already owned ? */                        /* Mutex already owned ? */
   if (NULL != mutex->owner)                          if (NULL != mutex->owner)
     {                                                  {
       /* Owned by us or by someone else ? */             /* Owned by us or by someone else ? */
       if (sos_thread_get_current() == mutex->o           if (sos_thread_get_current() == mutex->owner)
         {                                                  {
           /* Owned by us: do nothing */                      /* Owned by us: do nothing */
           retval = -SOS_EBUSY;                               retval = -SOS_EBUSY;
           goto exit_kmutex_lock;                             goto exit_kmutex_lock;
         }                                                  }
                                                    
       /* Wait for somebody to wake us */                 /* Wait for somebody to wake us */
       retval = sos_kwaitq_wait(& mutex->kwaitq           retval = sos_kwaitq_wait(& mutex->kwaitq, timeout);
                                                    
       /* Something wrong happened ? */                   /* Something wrong happened ? */
       if (SOS_OK != retval)                              if (SOS_OK != retval)
         {                                                  {
           goto exit_kmutex_lock;                             goto exit_kmutex_lock;
         }                                                  }
     }                                                  }
                                                    
   /* Ok, the mutex is available to us: take it       /* Ok, the mutex is available to us: take it */
   mutex->owner = sos_thread_get_current();           mutex->owner = sos_thread_get_current();
                                                    
  exit_kmutex_lock:                                  exit_kmutex_lock:
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_kmutex_trylock(struct sos_kmutex     sos_ret_t sos_kmutex_trylock(struct sos_kmutex *mutex)
 {                                                  {
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t retval;                                  sos_ret_t retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
                                                    
   /* Mutex available to us ? */                      /* Mutex available to us ? */
   if (NULL == mutex->owner)                          if (NULL == mutex->owner)
     {                                                  {
       /* Great ! Take it now */                          /* Great ! Take it now */
       mutex->owner = sos_thread_get_current();           mutex->owner = sos_thread_get_current();
                                                    
       retval = SOS_OK;                                   retval = SOS_OK;
     }                                                  }
   else                                               else
     {                                                  {
       /* No: signal it */                                /* No: signal it */
       retval = -SOS_EBUSY;                               retval = -SOS_EBUSY;
     }                                                  }
                                                    
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }
                                                    
                                                    
 sos_ret_t sos_kmutex_unlock(struct sos_kmutex      sos_ret_t sos_kmutex_unlock(struct sos_kmutex *mutex)
 {                                                  {
   sos_ui32_t flags;                                  sos_ui32_t flags;
   sos_ret_t  retval;                                 sos_ret_t  retval;
                                                    
   sos_disable_IRQs(flags);                           sos_disable_IRQs(flags);
                                                    
   if (sos_thread_get_current() != mutex->owner       if (sos_thread_get_current() != mutex->owner)
     retval = -SOS_EPERM;                               retval = -SOS_EPERM;
                                                    
   else if (sos_kwaitq_is_empty(& mutex->kwaitq       else if (sos_kwaitq_is_empty(& mutex->kwaitq))
     {                                                  {
       /*                                                 /*
        * There is NOT ANY thread waiting => we            * There is NOT ANY thread waiting => we really mark the mutex
        * as FREE                                          * as FREE
        */                                                 */
       mutex->owner = NULL;                               mutex->owner = NULL;
       retval = SOS_OK;                                   retval = SOS_OK;
     }                                                  }
   else                                               else
     {                                                  {
       /*                                                 /*
        * There is at least 1 thread waiting =>            * There is at least 1 thread waiting => we DO NOT mark the
        * mutex as free !                                  * mutex as free !
        * Actually, we should have written:                * Actually, we should have written:
        *   mutex->owner = thread_that_is_woken            *   mutex->owner = thread_that_is_woken_up;
        * But the real Id of the next thread ow            * But the real Id of the next thread owning the mutex is not
        * that important. What is important her            * that important. What is important here is that mutex->owner
        * IS NOT NULL. Otherwise there will be             * IS NOT NULL. Otherwise there will be a possibility for the
        * thread woken up here to have the mute            * thread woken up here to have the mutex stolen by a thread
        * locking the mutex in the meantime.               * locking the mutex in the meantime.
        */                                                 */
       retval = sos_kwaitq_wakeup(& mutex->kwai           retval = sos_kwaitq_wakeup(& mutex->kwaitq, 1, SOS_OK);
     }                                                  } 
                                                     
   sos_restore_IRQs(flags);                           sos_restore_IRQs(flags);
   return retval;                                     return retval;
 }                                                  }