dlls/ntdll/critsection.c

   1 /*
   2  * Win32 critical sections
   3  *
   4  * Copyright 1998 Alexandre Julliard
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #include <assert.h>
  25 #include <errno.h>
  26 #include <stdarg.h>
  27 #include <stdio.h>
  28 #include <sys/types.h>
  29 #include <time.h>
  30 #include "ntstatus.h"
  31 #define WIN32_NO_STATUS
  32 #include "windef.h"
  33 #include "winternl.h"
  34 #include "wine/debug.h"
  35 #include "ntdll_misc.h"
  36
  37 WINE_DEFAULT_DEBUG_CHANNEL(ntdll);
  38 WINE_DECLARE_DEBUG_CHANNEL(relay);
  39
  40 static inline LONG interlocked_inc( PLONG dest )
  41 {
  42     return interlocked_xchg_add( dest, 1 ) + 1;
  43 }
  44
  45 static inline LONG interlocked_dec( PLONG dest )
  46 {
  47     return interlocked_xchg_add( dest, -1 ) - 1;
  48 }
  49
  50 static inline void small_pause(void)
  51 {
  52 #ifdef __i386__
  53     __asm__ __volatile__( "rep;nop" : : : "memory" );
  54 #else
  55     __asm__ __volatile__( "" : : : "memory" );
  56 #endif
  57 }
  58
  59 #if defined(linux) && defined(__i386__)
  60
  61 static inline int futex_wait( int *addr, int val, struct timespec *timeout )
  62 {
  63     int res;
  64     __asm__ __volatile__( "xchgl %2,%%ebx\n\t"
  65                           "int $0x80\n\t"
  66                           "xchgl %2,%%ebx"
  67                           : "=a" (res)
  68                           : "0" (240) /* SYS_futex */, "D" (addr),
  69                             "c" (0) /* FUTEX_WAIT */, "d" (val), "S" (timeout) );
  70     return res;
  71 }
  72
  73 static inline int futex_wake( int *addr, int val )
  74 {
  75     int res;
  76     __asm__ __volatile__( "xchgl %2,%%ebx\n\t"
  77                           "int $0x80\n\t"
  78                           "xchgl %2,%%ebx"
  79                           : "=a" (res)
  80                           : "0" (240) /* SYS_futex */, "D" (addr),
  81                             "c" (1)  /* FUTEX_WAKE */, "d" (val) );
  82     return res;
  83 }
  84
  85 static inline int use_futexes(void)
  86 {
  87     static int supported = -1;
  88
  89     if (supported == -1) supported = (futex_wait( &supported, 10, NULL ) != -ENOSYS);
  90     return supported;
  91 }
  92
  93 static inline NTSTATUS fast_wait( RTL_CRITICAL_SECTION *crit, int timeout )
  94 {
  95     int val;
  96     struct timespec timespec;
  97
  98     if (!use_futexes()) return STATUS_NOT_IMPLEMENTED;
  99
 100     timespec.tv_sec  = timeout;
 101     timespec.tv_nsec = 0;
 102     while ((val = interlocked_cmpxchg( (int *)&crit->LockSemaphore, 0, 1 )) != 1)
 103     {
 104         /* note: this may wait longer than specified in case of signals or */
 105         /*       multiple wake-ups, but that shouldn't be a problem */
 106         if (futex_wait( (int *)&crit->LockSemaphore, val, &timespec ) == -ETIMEDOUT)
 107             return STATUS_TIMEOUT;
 108     }
 109     return STATUS_WAIT_0;
 110 }
 111
 112 static inline NTSTATUS fast_wake( RTL_CRITICAL_SECTION *crit )
 113 {
 114     if (!use_futexes()) return STATUS_NOT_IMPLEMENTED;
 115
 116     *(int *)&crit->LockSemaphore = 1;
 117     futex_wake( (int *)&crit->LockSemaphore, 1 );
 118     return STATUS_SUCCESS;
 119 }
 120
 121 static inline void close_semaphore( RTL_CRITICAL_SECTION *crit )
 122 {
 123     if (!use_futexes()) NtClose( crit->LockSemaphore );
 124 }
 125
 126 #elif defined(__APPLE__)
 127
 128 #include <mach/mach.h>
 129 #include <mach/task.h>
 130 #include <mach/semaphore.h>
 131
 132 static inline semaphore_t get_mach_semaphore( RTL_CRITICAL_SECTION *crit )
 133 {
 134     semaphore_t ret = *(int *)&crit->LockSemaphore;
 135     if (!ret)
 136     {
 137         semaphore_t sem;
 138         if (semaphore_create( mach_task_self(), &sem, SYNC_POLICY_FIFO, 0 )) return 0;
 139         if (!(ret = interlocked_cmpxchg( (int *)&crit->LockSemaphore, sem, 0 )))
 140             ret = sem;
 141         else
 142             semaphore_destroy( mach_task_self(), sem );  /* somebody beat us to it */
 143     }
 144     return ret;
 145 }
 146
 147 static inline NTSTATUS fast_wait( RTL_CRITICAL_SECTION *crit, int timeout )
 148 {
 149     mach_timespec_t timespec;
 150     semaphore_t sem = get_mach_semaphore( crit );
 151
 152     timespec.tv_sec = timeout;
 153     timespec.tv_nsec = 0;
 154     for (;;)
 155     {
 156         switch( semaphore_timedwait( sem, timespec ))
 157         {
 158         case KERN_SUCCESS:
 159             return STATUS_WAIT_0;
 160         case KERN_ABORTED:
 161             continue;  /* got a signal, restart */
 162         case KERN_OPERATION_TIMED_OUT:
 163             return STATUS_TIMEOUT;
 164         default:
 165             return STATUS_INVALID_HANDLE;
 166         }
 167     }
 168 }
 169
 170 static inline NTSTATUS fast_wake( RTL_CRITICAL_SECTION *crit )
 171 {
 172     semaphore_t sem = get_mach_semaphore( crit );
 173     semaphore_signal( sem );
 174     return STATUS_SUCCESS;
 175 }
 176
 177 static inline void close_semaphore( RTL_CRITICAL_SECTION *crit )
 178 {
 179     semaphore_destroy( mach_task_self(), *(int *)&crit->LockSemaphore );
 180 }
 181
 182 #else  /* __APPLE__ */
 183
 184 static inline NTSTATUS fast_wait( RTL_CRITICAL_SECTION *crit, int timeout )
 185 {
 186     return STATUS_NOT_IMPLEMENTED;
 187 }
 188
 189 static inline NTSTATUS fast_wake( RTL_CRITICAL_SECTION *crit )
 190 {
 191     return STATUS_NOT_IMPLEMENTED;
 192 }
 193
 194 static inline void close_semaphore( RTL_CRITICAL_SECTION *crit )
 195 {
 196     NtClose( crit->LockSemaphore );
 197 }
 198
 199 #endif
 200
 201 /***********************************************************************
 202  *           get_semaphore
 203  */
 204 static inline HANDLE get_semaphore( RTL_CRITICAL_SECTION *crit )
 205 {
 206     HANDLE ret = crit->LockSemaphore;
 207     if (!ret)
 208     {
 209         HANDLE sem;
 210         if (NtCreateSemaphore( &sem, SEMAPHORE_ALL_ACCESS, NULL, 0, 1 )) return 0;
 211         if (!(ret = interlocked_cmpxchg_ptr( &crit->LockSemaphore, sem, 0 )))
 212             ret = sem;
 213         else
 214             NtClose(sem);  /* somebody beat us to it */
 215     }
 216     return ret;
 217 }
 218
 219 /***********************************************************************
 220  *           wait_semaphore
 221  */
 222 static inline NTSTATUS wait_semaphore( RTL_CRITICAL_SECTION *crit, int timeout )
 223 {
 224     NTSTATUS ret;
 225
 226     /* debug info is cleared by MakeCriticalSectionGlobal */
 227     if (!crit->DebugInfo || ((ret = fast_wait( crit, timeout )) == STATUS_NOT_IMPLEMENTED))
 228     {
 229         HANDLE sem = get_semaphore( crit );
 230         LARGE_INTEGER time;
 231
 232         time.QuadPart = timeout * (LONGLONG)-10000000;
 233         ret = NTDLL_wait_for_multiple_objects( 1, &sem, 0, &time, 0 );
 234     }
 235     return ret;
 236 }
 237
 238 /***********************************************************************
 239  *           RtlInitializeCriticalSection   (NTDLL.@)
 240  *
 241  * Initialises a new critical section.
 242  *
 243  * PARAMS
 244  *  crit [O] Critical section to initialise
 245  *
 246  * RETURNS
 247  *  STATUS_SUCCESS.
 248  *
 249  * SEE
 250  *  RtlInitializeCriticalSectionEx(),
 251  *  RtlInitializeCriticalSectionAndSpinCount(), RtlDeleteCriticalSection(),
 252  *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
 253  *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
 254  */
 255 NTSTATUS WINAPI RtlInitializeCriticalSection( RTL_CRITICAL_SECTION *crit )
 256 {
 257     return RtlInitializeCriticalSectionEx( crit, 0, 0 );
 258 }
 259
 260 /***********************************************************************
 261  *           RtlInitializeCriticalSectionAndSpinCount   (NTDLL.@)
 262  *
 263  * Initialises a new critical section with a given spin count.
 264  *
 265  * PARAMS
 266  *   crit      [O] Critical section to initialise
 267  *   spincount [I] Spin count for crit
 268  *
 269  * RETURNS
 270  *  STATUS_SUCCESS.
 271  *
 272  * NOTES
 273  *  Available on NT4 SP3 or later.
 274  *
 275  * SEE
 276  *  RtlInitializeCriticalSectionEx(),
 277  *  RtlInitializeCriticalSection(), RtlDeleteCriticalSection(),
 278  *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
 279  *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
 280  */
 281 NTSTATUS WINAPI RtlInitializeCriticalSectionAndSpinCount( RTL_CRITICAL_SECTION *crit, ULONG spincount )
 282 {
 283     return RtlInitializeCriticalSectionEx( crit, spincount, 0 );
 284 }
 285
 286 /***********************************************************************
 287  *           RtlInitializeCriticalSectionEx   (NTDLL.@)
 288  *
 289  * Initialises a new critical section with a given spin count and flags.
 290  *
 291  * PARAMS
 292  *   crit      [O] Critical section to initialise.
 293  *   spincount [I] Number of times to spin upon contention.
 294  *   flags     [I] RTL_CRITICAL_SECTION_FLAG_ flags from winnt.h.
 295  *
 296  * RETURNS
 297  *  STATUS_SUCCESS.
 298  *
 299  * NOTES
 300  *  Available on Vista or later.
 301  *
 302  * SEE
 303  *  RtlInitializeCriticalSection(), RtlDeleteCriticalSection(),
 304  *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
 305  *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
 306  */
 307 NTSTATUS WINAPI RtlInitializeCriticalSectionEx( RTL_CRITICAL_SECTION *crit, ULONG spincount, ULONG flags )
 308 {
 309     if (flags & (RTL_CRITICAL_SECTION_FLAG_DYNAMIC_SPIN|RTL_CRITICAL_SECTION_FLAG_STATIC_INIT))
 310         FIXME("(%p,%u,0x%08x) semi-stub\n", crit, spincount, flags);
 311
 312     /* FIXME: if RTL_CRITICAL_SECTION_FLAG_STATIC_INIT is given, we should use
 313      * memory from a static pool to hold the debug info. Then heap.c could pass
 314      * this flag rather than initialising the process heap CS by hand. If this
 315      * is done, then debug info should be managed through Rtlp[Allocate|Free]DebugInfo
 316      * so (e.g.) MakeCriticalSectionGlobal() doesn't free it using HeapFree().
 317      */
 318     if (flags & RTL_CRITICAL_SECTION_FLAG_NO_DEBUG_INFO)
 319         crit->DebugInfo = NULL;
 320     else
 321         crit->DebugInfo = RtlAllocateHeap(GetProcessHeap(), 0, sizeof(RTL_CRITICAL_SECTION_DEBUG));
 322
 323     if (crit->DebugInfo)
 324     {
 325         crit->DebugInfo->Type = 0;
 326         crit->DebugInfo->CreatorBackTraceIndex = 0;
 327         crit->DebugInfo->CriticalSection = crit;
 328         crit->DebugInfo->ProcessLocksList.Blink = &(crit->DebugInfo->ProcessLocksList);
 329         crit->DebugInfo->ProcessLocksList.Flink = &(crit->DebugInfo->ProcessLocksList);
 330         crit->DebugInfo->EntryCount = 0;
 331         crit->DebugInfo->ContentionCount = 0;
 332         memset( crit->DebugInfo->Spare, 0, sizeof(crit->DebugInfo->Spare) );
 333     }
 334     crit->LockCount      = -1;
 335     crit->RecursionCount = 0;
 336     crit->OwningThread   = 0;
 337     crit->LockSemaphore  = 0;
 338     if (NtCurrentTeb()->Peb->NumberOfProcessors <= 1) spincount = 0;
 339     crit->SpinCount = spincount & ~0x80000000;
 340     return STATUS_SUCCESS;
 341 }
 342
 343 /***********************************************************************
 344  *           RtlSetCriticalSectionSpinCount   (NTDLL.@)
 345  *
 346  * Sets the spin count of a critical section.
 347  *
 348  * PARAMS
 349  *   crit      [I/O] Critical section
 350  *   spincount [I] Spin count for crit
 351  *
 352  * RETURNS
 353  *  The previous spin count.
 354  *
 355  * NOTES
 356  *  If the system is not SMP, spincount is ignored and set to 0.
 357  *
 358  * SEE
 359  *  RtlInitializeCriticalSectionEx(),
 360  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 361  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 362  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
 363  */
 364 ULONG WINAPI RtlSetCriticalSectionSpinCount( RTL_CRITICAL_SECTION *crit, ULONG spincount )
 365 {
 366     ULONG oldspincount = crit->SpinCount;
 367     if (NtCurrentTeb()->Peb->NumberOfProcessors <= 1) spincount = 0;
 368     crit->SpinCount = spincount;
 369     return oldspincount;
 370 }
 371
 372 /***********************************************************************
 373  *           RtlDeleteCriticalSection   (NTDLL.@)
 374  *
 375  * Frees the resources used by a critical section.
 376  *
 377  * PARAMS
 378  *  crit [I/O] Critical section to free
 379  *
 380  * RETURNS
 381  *  STATUS_SUCCESS.
 382  *
 383  * SEE
 384  *  RtlInitializeCriticalSectionEx(),
 385  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 386  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 387  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
 388  */
 389 NTSTATUS WINAPI RtlDeleteCriticalSection( RTL_CRITICAL_SECTION *crit )
 390 {
 391     crit->LockCount      = -1;
 392     crit->RecursionCount = 0;
 393     crit->OwningThread   = 0;
 394     if (crit->DebugInfo)
 395     {
 396         /* only free the ones we made in here */
 397         if (!crit->DebugInfo->Spare[0])
 398         {
 399             RtlFreeHeap( GetProcessHeap(), 0, crit->DebugInfo );
 400             crit->DebugInfo = NULL;
 401         }
 402         close_semaphore( crit );
 403     }
 404     else NtClose( crit->LockSemaphore );
 405     crit->LockSemaphore = 0;
 406     return STATUS_SUCCESS;
 407 }
 408
 409
 410 /***********************************************************************
 411  *           RtlpWaitForCriticalSection   (NTDLL.@)
 412  *
 413  * Waits for a busy critical section to become free.
 414  *
 415  * PARAMS
 416  *  crit [I/O] Critical section to wait for
 417  *
 418  * RETURNS
 419  *  STATUS_SUCCESS.
 420  *
 421  * NOTES
 422  *  Use RtlEnterCriticalSection() instead of this function as it is often much
 423  *  faster.
 424  *
 425  * SEE
 426  *  RtlInitializeCriticalSectionEx(),
 427  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 428  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 429  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
 430  */
 431 NTSTATUS WINAPI RtlpWaitForCriticalSection( RTL_CRITICAL_SECTION *crit )
 432 {
 433     for (;;)
 434     {
 435         EXCEPTION_RECORD rec;
 436         NTSTATUS status = wait_semaphore( crit, 5 );
 437
 438         if ( status == STATUS_TIMEOUT )
 439         {
 440             const char *name = NULL;
 441             if (crit->DebugInfo) name = (char *)crit->DebugInfo->Spare[0];
 442             if (!name) name = "?";
 443             ERR( "section %p %s wait timed out in thread %04x, blocked by %04x, retrying (60 sec)\n",
 444                  crit, debugstr_a(name), GetCurrentThreadId(), HandleToULong(crit->OwningThread) );
 445             status = wait_semaphore( crit, 60 );
 446             if ( status == STATUS_TIMEOUT && TRACE_ON(relay) )
 447             {
 448                 ERR( "section %p %s wait timed out in thread %04x, blocked by %04x, retrying (5 min)\n",
 449                      crit, debugstr_a(name), GetCurrentThreadId(), HandleToULong(crit->OwningThread) );
 450                 status = wait_semaphore( crit, 300 );
 451             }
 452         }
 453         if (status == STATUS_WAIT_0) break;
 454
 455         /* Throw exception only for Wine internal locks */
 456         if ((!crit->DebugInfo) || (!crit->DebugInfo->Spare[0])) continue;
 457
 458         rec.ExceptionCode    = STATUS_POSSIBLE_DEADLOCK;
 459         rec.ExceptionFlags   = 0;
 460         rec.ExceptionRecord  = NULL;
 461         rec.ExceptionAddress = RtlRaiseException;  /* sic */
 462         rec.NumberParameters = 1;
 463         rec.ExceptionInformation[0] = (ULONG_PTR)crit;
 464         RtlRaiseException( &rec );
 465     }
 466     if (crit->DebugInfo) crit->DebugInfo->ContentionCount++;
 467     return STATUS_SUCCESS;
 468 }
 469
 470
 471 /***********************************************************************
 472  *           RtlpUnWaitCriticalSection   (NTDLL.@)
 473  *
 474  * Notifies other threads waiting on the busy critical section that it has
 475  * become free.
 476  *
 477  * PARAMS
 478  *  crit [I/O] Critical section
 479  *
 480  * RETURNS
 481  *  Success: STATUS_SUCCESS.
 482  *  Failure: Any error returned by NtReleaseSemaphore()
 483  *
 484  * NOTES
 485  *  Use RtlLeaveCriticalSection() instead of this function as it is often much
 486  *  faster.
 487  *
 488  * SEE
 489  *  RtlInitializeCriticalSectionEx(),
 490  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 491  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 492  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
 493  */
 494 NTSTATUS WINAPI RtlpUnWaitCriticalSection( RTL_CRITICAL_SECTION *crit )
 495 {
 496     NTSTATUS ret;
 497
 498     /* debug info is cleared by MakeCriticalSectionGlobal */
 499     if (!crit->DebugInfo || ((ret = fast_wake( crit )) == STATUS_NOT_IMPLEMENTED))
 500     {
 501         HANDLE sem = get_semaphore( crit );
 502         ret = NtReleaseSemaphore( sem, 1, NULL );
 503     }
 504     if (ret) RtlRaiseStatus( ret );
 505     return ret;
 506 }
 507
 508
 509 /***********************************************************************
 510  *           RtlEnterCriticalSection   (NTDLL.@)
 511  *
 512  * Enters a critical section, waiting for it to become available if necessary.
 513  *
 514  * PARAMS
 515  *  crit [I/O] Critical section to enter
 516  *
 517  * RETURNS
 518  *  STATUS_SUCCESS. The critical section is held by the caller.
 519  *
 520  * SEE
 521  *  RtlInitializeCriticalSectionEx(),
 522  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 523  *  RtlDeleteCriticalSection(), RtlSetCriticalSectionSpinCount(),
 524  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
 525  */
 526 NTSTATUS WINAPI RtlEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
 527 {
 528     if (crit->SpinCount)
 529     {
 530         ULONG count;
 531
 532         if (RtlTryEnterCriticalSection( crit )) return STATUS_SUCCESS;
 533         for (count = crit->SpinCount; count > 0; count--)
 534         {
 535             if (crit->LockCount > 0) break;  /* more than one waiter, don't bother spinning */
 536             if (crit->LockCount == -1)       /* try again */
 537             {
 538                 if (interlocked_cmpxchg( &crit->LockCount, 0, -1 ) == -1) goto done;
 539             }
 540             small_pause();
 541         }
 542     }
 543
 544     if (interlocked_inc( &crit->LockCount ))
 545     {
 546         if (crit->OwningThread == ULongToHandle(GetCurrentThreadId()))
 547         {
 548             crit->RecursionCount++;
 549             return STATUS_SUCCESS;
 550         }
 551
 552         /* Now wait for it */
 553         RtlpWaitForCriticalSection( crit );
 554     }
 555 done:
 556     crit->OwningThread   = ULongToHandle(GetCurrentThreadId());
 557     crit->RecursionCount = 1;
 558     return STATUS_SUCCESS;
 559 }
 560
 561
 562 /***********************************************************************
 563  *           RtlTryEnterCriticalSection   (NTDLL.@)
 564  *
 565  * Tries to enter a critical section without waiting.
 566  *
 567  * PARAMS
 568  *  crit [I/O] Critical section to enter
 569  *
 570  * RETURNS
 571  *  Success: TRUE. The critical section is held by the caller.
 572  *  Failure: FALSE. The critical section is currently held by another thread.
 573  *
 574  * SEE
 575  *  RtlInitializeCriticalSectionEx(),
 576  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 577  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 578  *  RtlLeaveCriticalSection(), RtlSetCriticalSectionSpinCount()
 579  */
 580 BOOL WINAPI RtlTryEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
 581 {
 582     BOOL ret = FALSE;
 583     if (interlocked_cmpxchg( &crit->LockCount, 0, -1 ) == -1)
 584     {
 585         crit->OwningThread   = ULongToHandle(GetCurrentThreadId());
 586         crit->RecursionCount = 1;
 587         ret = TRUE;
 588     }
 589     else if (crit->OwningThread == ULongToHandle(GetCurrentThreadId()))
 590     {
 591         interlocked_inc( &crit->LockCount );
 592         crit->RecursionCount++;
 593         ret = TRUE;
 594     }
 595     return ret;
 596 }
 597
 598
 599 /***********************************************************************
 600  *           RtlLeaveCriticalSection   (NTDLL.@)
 601  *
 602  * Leaves a critical section.
 603  *
 604  * PARAMS
 605  *  crit [I/O] Critical section to leave.
 606  *
 607  * RETURNS
 608  *  STATUS_SUCCESS.
 609  *
 610  * SEE
 611  *  RtlInitializeCriticalSectionEx(),
 612  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
 613  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
 614  *  RtlSetCriticalSectionSpinCount(), RtlTryEnterCriticalSection()
 615  */
 616 NTSTATUS WINAPI RtlLeaveCriticalSection( RTL_CRITICAL_SECTION *crit )
 617 {
 618     if (--crit->RecursionCount) interlocked_dec( &crit->LockCount );
 619     else
 620     {
 621         crit->OwningThread = 0;
 622         if (interlocked_dec( &crit->LockCount ) >= 0)
 623         {
 624             /* someone is waiting */
 625             RtlpUnWaitCriticalSection( crit );
 626         }
 627     }
 628     return STATUS_SUCCESS;
 629 }