server/mutex.c

   1 /*
   2  * Server-side mutex management
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  */
   6
   7 #include <assert.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10
  11 #include "winerror.h"
  12 #include "winnt.h"
  13
  14 #include "handle.h"
  15 #include "thread.h"
  16 #include "request.h"
  17
  18 struct mutex
  19 {
  20     struct object  obj;             /* object header */
  21     struct thread *owner;           /* mutex owner */
  22     unsigned int   count;           /* recursion count */
  23     int            abandoned;       /* has it been abandoned? */
  24     struct mutex  *next;
  25     struct mutex  *prev;
  26 };
  27
  28 static void mutex_dump( struct object *obj, int verbose );
  29 static int mutex_signaled( struct object *obj, struct thread *thread );
  30 static int mutex_satisfied( struct object *obj, struct thread *thread );
  31 static void mutex_destroy( struct object *obj );
  32
  33 static const struct object_ops mutex_ops =
  34 {
  35     sizeof(struct mutex),
  36     mutex_dump,
  37     add_queue,
  38     remove_queue,
  39     mutex_signaled,
  40     mutex_satisfied,
  41     no_read_fd,
  42     no_write_fd,
  43     no_flush,
  44     no_get_file_info,
  45     mutex_destroy
  46 };
  47
  48
  49 static struct mutex *create_mutex( const char *name, size_t len, int owned )
  50 {
  51     struct mutex *mutex;
  52
  53     if ((mutex = create_named_object( &mutex_ops, name, len )))
  54     {
  55         if (get_error() != ERROR_ALREADY_EXISTS)
  56         {
  57             /* initialize it if it didn't already exist */
  58             mutex->count = 0;
  59             mutex->owner = NULL;
  60             mutex->abandoned = 0;
  61             mutex->next = mutex->prev = NULL;
  62             if (owned) mutex_satisfied( &mutex->obj, current );
  63         }
  64     }
  65     return mutex;
  66 }
  67
  68 /* release a mutex once the recursion count is 0 */
  69 static void do_release( struct mutex *mutex )
  70 {
  71     assert( !mutex->count );
  72     /* remove the mutex from the thread list of owned mutexes */
  73     if (mutex->next) mutex->next->prev = mutex->prev;
  74     if (mutex->prev) mutex->prev->next = mutex->next;
  75     else mutex->owner->mutex = mutex->next;
  76     mutex->owner = NULL;
  77     mutex->next = mutex->prev = NULL;
  78     wake_up( &mutex->obj, 0 );
  79 }
  80
  81 void abandon_mutexes( struct thread *thread )
  82 {
  83     while (thread->mutex)
  84     {
  85         struct mutex *mutex = thread->mutex;
  86         assert( mutex->owner == thread );
  87         mutex->count = 0;
  88         mutex->abandoned = 1;
  89         do_release( mutex );
  90     }
  91 }
  92
  93 static void mutex_dump( struct object *obj, int verbose )
  94 {
  95     struct mutex *mutex = (struct mutex *)obj;
  96     assert( obj->ops == &mutex_ops );
  97     printf( "Mutex count=%u owner=%p name='%s'\n",
  98             mutex->count, mutex->owner, get_object_name( &mutex->obj) );
  99 }
 100
 101 static int mutex_signaled( struct object *obj, struct thread *thread )
 102 {
 103     struct mutex *mutex = (struct mutex *)obj;
 104     assert( obj->ops == &mutex_ops );
 105     return (!mutex->count || (mutex->owner == thread));
 106 }
 107
 108 static int mutex_satisfied( struct object *obj, struct thread *thread )
 109 {
 110     struct mutex *mutex = (struct mutex *)obj;
 111     assert( obj->ops == &mutex_ops );
 112     assert( !mutex->count || (mutex->owner == thread) );
 113
 114     if (!mutex->count++)  /* FIXME: avoid wrap-around */
 115     {
 116         assert( !mutex->owner );
 117         mutex->owner = thread;
 118         mutex->prev  = NULL;
 119         if ((mutex->next = thread->mutex)) mutex->next->prev = mutex;
 120         thread->mutex = mutex;
 121     }
 122     if (!mutex->abandoned) return 0;
 123     mutex->abandoned = 0;
 124     return 1;
 125 }
 126
 127 static void mutex_destroy( struct object *obj )
 128 {
 129     struct mutex *mutex = (struct mutex *)obj;
 130     assert( obj->ops == &mutex_ops );
 131
 132     if (!mutex->count) return;
 133     mutex->count = 0;
 134     do_release( mutex );
 135 }
 136
 137 /* create a mutex */
 138 DECL_HANDLER(create_mutex)
 139 {
 140     size_t len = get_req_strlen( req->name );
 141     struct mutex *mutex;
 142
 143     req->handle = -1;
 144     if ((mutex = create_mutex( req->name, len, req->owned )))
 145     {
 146         req->handle = alloc_handle( current->process, mutex, MUTEX_ALL_ACCESS, req->inherit );
 147         release_object( mutex );
 148     }
 149 }
 150
 151 /* open a handle to a mutex */
 152 DECL_HANDLER(open_mutex)
 153 {
 154     size_t len = get_req_strlen( req->name );
 155     req->handle = open_object( req->name, len, &mutex_ops, req->access, req->inherit );
 156 }
 157
 158 /* release a mutex */
 159 DECL_HANDLER(release_mutex)
 160 {
 161     struct mutex *mutex;
 162
 163     if ((mutex = (struct mutex *)get_handle_obj( current->process, req->handle,
 164                                                  MUTEX_MODIFY_STATE, &mutex_ops )))
 165     {
 166         if (!mutex->count || (mutex->owner != current)) set_error( ERROR_NOT_OWNER );
 167         else if (!--mutex->count) do_release( mutex );
 168         release_object( mutex );
 169     }
 170 }