iokit/IOKit/IOLocks.h

   1 /*
   2  * Copyright (c) 1998-2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
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  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  *
  30  */
  31
  32 #ifndef __IOKIT_IOLOCKS_H
  33 #define __IOKIT_IOLOCKS_H
  34
  35 #ifndef KERNEL
  36 #error IOLocks.h is for kernel use only
  37 #endif
  38
  39 #include <sys/appleapiopts.h>
  40 #include <sys/cdefs.h>
  41
  42 #include <IOKit/system.h>
  43
  44 #include <IOKit/IOReturn.h>
  45 #include <IOKit/IOTypes.h>
  46
  47 #ifdef __cplusplus
  48 extern "C" {
  49 #endif
  50
  51 #include <libkern/locks.h>
  52 #include <machine/machine_routines.h>
  53
  54 /*! @var IOLockGroup
  55     Global lock group used by all IOKit locks.  To simplify kext debugging and lock-heat analysis, consider using lck_* locks with a per-driver lock group, as defined in kern/locks.h.
  56 */
  57 extern lck_grp_t        *IOLockGroup;
  58
  59 #if defined(XNU_KERNEL_PRIVATE)
  60 #define IOLOCKS_INLINE  1
  61 #endif
  62
  63 /*
  64  * Mutex lock operations
  65  */
  66
  67 #ifdef  IOLOCKS_INLINE
  68 typedef lck_mtx_t       IOLock;
  69 #else
  70 typedef struct _IOLock  IOLock;
  71 #endif  /* IOLOCKS_INLINE */
  72
  73
  74 /*! @function IOLockAlloc
  75     @abstract Allocates and initializes a mutex.
  76     @discussion Allocates a mutex in general purpose memory, and initializes it. Mutexes are general purpose blocking mutual exclusion locks, supplied by libkern/locks.h. This function may block and so should not be called from interrupt level or while a spin lock is held.  IOLocks use the global IOKit lock group, IOLockGroup.  To simplify kext debugging and lock-heat analysis, consider using lck_* locks with a per-driver lock group, as defined in kern/locks.h.
  77     @result Pointer to the allocated lock, or zero on failure. */
  78
  79 IOLock * IOLockAlloc( void );
  80
  81 /*! @function IOLockFree
  82     @abstract Frees a mutex.
  83     @discussion Frees a lock allocated with IOLockAlloc. Mutex should be unlocked with no waiters.
  84     @param lock Pointer to the allocated lock. */
  85
  86 void    IOLockFree( IOLock * lock);
  87
  88 /*! @function IOLockGetMachLock
  89     @abstract Accessor to a Mach mutex.
  90     @discussion Accessor to the Mach mutex.
  91     @param lock Pointer to the allocated lock. */
  92
  93 lck_mtx_t * IOLockGetMachLock( IOLock * lock);
  94
  95 /*! @function IOLockLock
  96     @abstract Lock a mutex.
  97     @discussion Lock the mutex. If the lock is held by any thread, block waiting for its unlock. This function may block and so should not be called from interrupt level or while a spin lock is held. Locking the mutex recursively from one thread will result in deadlock.
  98     @param lock Pointer to the allocated lock. */
  99
 100 #ifdef  IOLOCKS_INLINE
 101 #define IOLockLock(l)   lck_mtx_lock(l)
 102 #else
 103 void    IOLockLock( IOLock * lock);
 104 #endif  /* !IOLOCKS_INLINE */
 105
 106 /*! @function IOLockTryLock
 107     @abstract Attempt to lock a mutex.
 108     @discussion Lock the mutex if it is currently unlocked, and return true. If the lock is held by any thread, return false.
 109     @param lock Pointer to the allocated lock.
 110     @result True if the mutex was unlocked and is now locked by the caller, otherwise false. */
 111
 112 #ifdef  IOLOCKS_INLINE
 113 #define IOLockTryLock(l)        lck_mtx_try_lock(l)
 114 #else
 115 boolean_t IOLockTryLock( IOLock * lock);
 116 #endif  /* !IOLOCKS_INLINE */
 117
 118 /*! @function IOLockUnlock
 119     @abstract Unlock a mutex.
 120 @discussion Unlock the mutex and wake any blocked waiters. Results are undefined if the caller has not locked the mutex. This function may block and so should not be called from interrupt level or while a spin lock is held.
 121     @param lock Pointer to the allocated lock. */
 122
 123 #ifdef  IOLOCKS_INLINE
 124 #define IOLockUnlock(l) lck_mtx_unlock(l)
 125 #else
 126 void    IOLockUnlock( IOLock * lock);
 127 #endif  /* !IOLOCKS_INLINE */
 128
 129 /*! @function IOLockSleep
 130     @abstract Sleep with mutex unlock and relock
 131 @discussion Prepare to sleep,unlock the mutex, and re-acquire it on wakeup. Results are undefined if the caller has not locked the mutex. This function may block and so should not be called from interrupt level or while a spin lock is held.
 132     @param lock Pointer to the locked lock.
 133     @param event The event to sleep on. Must be non-NULL.
 134     @param interType How can the sleep be interrupted.
 135         @result The wait-result value indicating how the thread was awakened.*/
 136 int     IOLockSleep( IOLock * lock, void *event, UInt32 interType) __DARWIN14_ALIAS(IOLockSleep);
 137
 138 int     IOLockSleepDeadline( IOLock * lock, void *event,
 139                                                  AbsoluteTime deadline, UInt32 interType) __DARWIN14_ALIAS(IOLockSleepDeadline);
 140
 141 void    IOLockWakeup(IOLock * lock, void *event, bool oneThread) __DARWIN14_ALIAS(IOLockWakeup);
 142
 143 #ifdef XNU_KERNEL_PRIVATE
 144 /*! @enum     IOLockAssertState
 145  *  @abstract Used with IOLockAssert to assert the state of a lock.
 146  */
 147 typedef enum {
 148     kIOLockAssertOwned    = LCK_ASSERT_OWNED,
 149     kIOLockAssertNotOwned = LCK_ASSERT_NOTOWNED
 150 } IOLockAssertState;
 151
 152 #ifdef IOLOCKS_INLINE
 153 #define IOLockAssert(l, type) LCK_MTX_ASSERT(l, type)
 154 #else
 155 /*! @function   IOLockAssert
 156  *  @abstract   Assert that lock is either held or not held by current thread.
 157  *  @discussion Call with either kIOLockAssertOwned or kIOLockAssertNotOwned.
 158  *  Panics the kernel if the lock is not owned if called with kIOLockAssertOwned,
 159  *  and vice-versa.
 160  */
 161 void    IOLockAssert(IOLock * lock, IOLockAssertState type);
 162 #endif /* !IOLOCKS_INLINE */
 163 #endif /* !XNU_KERNEL_PRIVATE */
 164
 165 #ifdef __APPLE_API_OBSOLETE
 166
 167 /* The following API is deprecated */
 168
 169 typedef enum {
 170     kIOLockStateUnlocked        = 0,
 171     kIOLockStateLocked          = 1
 172 } IOLockState;
 173
 174 void    IOLockInitWithState( IOLock * lock, IOLockState state);
 175 #define IOLockInit( l ) IOLockInitWithState( l, kIOLockStateUnlocked);
 176
 177 static __inline__ void IOTakeLock( IOLock * lock) { IOLockLock(lock);        }
 178 static __inline__ boolean_t IOTryLock(  IOLock * lock) { return(IOLockTryLock(lock)); }
 179 static __inline__ void IOUnlock(   IOLock * lock) { IOLockUnlock(lock);      }
 180
 181 #endif /* __APPLE_API_OBSOLETE */
 182
 183 /*
 184  * Recursive lock operations
 185  */
 186
 187 typedef struct _IORecursiveLock IORecursiveLock;
 188
 189 /*! @function IORecursiveLockAlloc
 190     @abstract Allocates and initializes an recursive lock.
 191     @discussion Allocates a recursive lock in general purpose memory, and initializes it. Recursive locks function identically to mutexes but allow one thread to lock more than once, with balanced unlocks.  IORecursiveLocks use the global IOKit lock group, IOLockGroup.  To simplify kext debugging and lock-heat analysis, consider using lck_* locks with a per-driver lock group, as defined in kern/locks.h.
 192     @result Pointer to the allocated lock, or zero on failure. */
 193
 194 IORecursiveLock * IORecursiveLockAlloc( void );
 195
 196 /*! @function IORecursiveLockFree
 197     @abstract Frees a recursive lock.
 198     @discussion Frees a lock allocated with IORecursiveLockAlloc. Lock should be unlocked with no waiters.
 199     @param lock Pointer to the allocated lock. */
 200
 201 void            IORecursiveLockFree( IORecursiveLock * lock);
 202
 203 /*! @function IORecursiveLockGetMachLock
 204     @abstract Accessor to a Mach mutex.
 205     @discussion Accessor to the Mach mutex.
 206     @param lock Pointer to the allocated lock. */
 207
 208 lck_mtx_t * IORecursiveLockGetMachLock( IORecursiveLock * lock);
 209
 210 /*! @function IORecursiveLockLock
 211     @abstract Lock a recursive lock.
 212     @discussion Lock the recursive lock. If the lock is held by another thread, block waiting for its unlock. This function may block and so should not be called from interrupt level or while a spin lock is held. The lock may be taken recursively by the same thread, with a balanced number of calls to IORecursiveLockUnlock.
 213     @param lock Pointer to the allocated lock. */
 214
 215 void            IORecursiveLockLock( IORecursiveLock * lock);
 216
 217 /*! @function IORecursiveLockTryLock
 218     @abstract Attempt to lock a recursive lock.
 219     @discussion Lock the lock if it is currently unlocked, or held by the calling thread, and return true. If the lock is held by another thread, return false. Successful calls to IORecursiveLockTryLock should be balanced with calls to IORecursiveLockUnlock.
 220     @param lock Pointer to the allocated lock.
 221     @result True if the lock is now locked by the caller, otherwise false. */
 222
 223 boolean_t       IORecursiveLockTryLock( IORecursiveLock * lock);
 224
 225 /*! @function IORecursiveLockUnlock
 226     @abstract Unlock a recursive lock.
 227 @discussion Undo one call to IORecursiveLockLock, if the lock is now unlocked wake any blocked waiters. Results are undefined if the caller does not balance calls to IORecursiveLockLock with IORecursiveLockUnlock. This function may block and so should not be called from interrupt level or while a spin lock is held.
 228     @param lock Pointer to the allocated lock. */
 229
 230 void            IORecursiveLockUnlock( IORecursiveLock * lock);
 231
 232 /*! @function IORecursiveLockHaveLock
 233     @abstract Check if a recursive lock is held by the calling thread.
 234     @discussion If the lock is held by the calling thread, return true, otherwise the lock is unlocked, or held by another thread and false is returned.
 235     @param lock Pointer to the allocated lock.
 236     @result True if the calling thread holds the lock otherwise false. */
 237
 238 boolean_t       IORecursiveLockHaveLock( const IORecursiveLock * lock);
 239
 240 extern int      IORecursiveLockSleep( IORecursiveLock *_lock,
 241                                       void *event, UInt32 interType);
 242 extern int      IORecursiveLockSleepDeadline( IORecursiveLock * _lock, void *event,
 243                                                                                         AbsoluteTime deadline, UInt32 interType);
 244 extern void     IORecursiveLockWakeup( IORecursiveLock *_lock,
 245                                        void *event, bool oneThread);
 246
 247 /*
 248  * Complex (read/write) lock operations
 249  */
 250
 251 #ifdef  IOLOCKS_INLINE
 252 typedef lck_rw_t                IORWLock;
 253 #else
 254 typedef struct _IORWLock        IORWLock;
 255 #endif  /* IOLOCKS_INLINE */
 256
 257 /*! @function IORWLockAlloc
 258     @abstract Allocates and initializes a read/write lock.
 259     @discussion Allocates and initializes a read/write lock in general purpose memory. Read/write locks provide for multiple readers, one exclusive writer, and are supplied by libkern/locks.h. This function may block and so should not be called from interrupt level or while a spin lock is held.  IORWLocks use the global IOKit lock group, IOLockGroup.  To simplify kext debugging and lock-heat analysis, consider using lck_* locks with a per-driver lock group, as defined in kern/locks.h.
 260     @result Pointer to the allocated lock, or zero on failure. */
 261
 262 IORWLock * IORWLockAlloc( void );
 263
 264 /*! @function IORWLockFree
 265    @abstract Frees a read/write lock.
 266    @discussion Frees a lock allocated with IORWLockAlloc. Lock should be unlocked with no waiters.
 267     @param lock Pointer to the allocated lock. */
 268
 269 void    IORWLockFree( IORWLock * lock);
 270
 271 /*! @function IORWLockGetMachLock
 272     @abstract Accessor to a Mach read/write lock.
 273     @discussion Accessor to the Mach read/write lock.
 274     @param lock Pointer to the allocated lock. */
 275
 276 lck_rw_t * IORWLockGetMachLock( IORWLock * lock);
 277
 278 /*! @function IORWLockRead
 279     @abstract Lock a read/write lock for read.
 280 @discussion Lock the lock for read, allowing multiple readers when there are no writers. If the lock is held for write, block waiting for its unlock. This function may block and so should not be called from interrupt level or while a spin lock is held. Locking the lock recursively from one thread, for read or write, can result in deadlock.
 281     @param lock Pointer to the allocated lock. */
 282
 283 #ifdef  IOLOCKS_INLINE
 284 #define IORWLockRead(l) lck_rw_lock_shared(l)
 285 #else
 286 void    IORWLockRead(IORWLock * lock);
 287 #endif  /* !IOLOCKS_INLINE */
 288
 289 /*! @function IORWLockWrite
 290     @abstract Lock a read/write lock for write.
 291     @discussion Lock the lock for write, allowing one writer exlusive access. If the lock is held for read or write, block waiting for its unlock. This function may block and so should not be called from interrupt level or while a spin lock is held. Locking the lock recursively from one thread, for read or write, can result in deadlock.
 292     @param lock Pointer to the allocated lock. */
 293
 294 #ifdef  IOLOCKS_INLINE
 295 #define IORWLockWrite(l)        lck_rw_lock_exclusive(l)
 296 #else
 297 void    IORWLockWrite( IORWLock * lock);
 298 #endif  /* !IOLOCKS_INLINE */
 299
 300 /*! @function IORWLockUnlock
 301     @abstract Unlock a read/write lock.
 302     @discussion Undo one call to IORWLockRead or IORWLockWrite. Results are undefined if the caller has not locked the lock. This function may block and so should not be called from interrupt level or while a spin lock is held.
 303     @param lock Pointer to the allocated lock. */
 304
 305 #ifdef  IOLOCKS_INLINE
 306 #define IORWLockUnlock(l)       lck_rw_done(l)
 307 #else
 308 void    IORWLockUnlock( IORWLock * lock);
 309 #endif  /* !IOLOCKS_INLINE */
 310
 311 #ifdef XNU_KERNEL_PRIVATE
 312 /*! @enum     IORWLockAssertState
 313  *  @abstract Used with IORWLockAssert to assert the state of a lock.
 314  */
 315 typedef enum {
 316     kIORWLockAssertRead    = LCK_RW_ASSERT_SHARED,
 317     kIORWLockAssertWrite   = LCK_RW_ASSERT_EXCLUSIVE,
 318     kIORWLockAssertHeld    = LCK_RW_ASSERT_HELD,
 319     kIORWLockAssertNotHeld = LCK_RW_ASSERT_NOTHELD
 320 } IORWLockAssertState;
 321
 322 #ifdef IOLOCKS_INLINE
 323 #define IORWLockAssert(l, type) LCK_RW_ASSERT(l, type)
 324 #else
 325 /*! @function   IORWLockAssert
 326  *  @abstract   Assert that a reader-writer lock is either held or not held
 327  *  by the current thread.
 328  *  @discussion Call with a value defined by the IORWLockAssertState type.
 329  *  If the specified lock is not in the state specified by the type argument,
 330  *  then the kernel will panic.
 331  */
 332 void    IORWLockAssert(IORWLock * lock, IORWLockAssertState type);
 333 #endif /* !IOLOCKS_INLINE */
 334 #endif /* !XNU_KERNEL_PRIVATE */
 335
 336 #ifdef __APPLE_API_OBSOLETE
 337
 338 /* The following API is deprecated */
 339
 340 static __inline__ void IOReadLock( IORWLock * lock)   { IORWLockRead(lock);   }
 341 static __inline__ void IOWriteLock(  IORWLock * lock) { IORWLockWrite(lock);  }
 342 static __inline__ void IORWUnlock(   IORWLock * lock) { IORWLockUnlock(lock); }
 343
 344 #endif /* __APPLE_API_OBSOLETE */
 345
 346
 347 /*
 348  * Simple locks. Cannot block while holding a simple lock.
 349  */
 350
 351 #ifdef  IOLOCKS_INLINE
 352 typedef lck_spin_t              IOSimpleLock;
 353 #else
 354 typedef struct _IOSimpleLock    IOSimpleLock;
 355 #endif  /* IOLOCKS_INLINE */
 356
 357 /*! @function IOSimpleLockAlloc
 358     @abstract Allocates and initializes a spin lock.
 359     @discussion Allocates and initializes a spin lock in general purpose memory. Spin locks provide non-blocking mutual exclusion for synchronization between thread context and interrupt context, or for multiprocessor synchronization, and are supplied by libkern/locks.h. This function may block and so should not be called from interrupt level or while a spin lock is held.  IOSimpleLocks use the global IOKit lock group, IOLockGroup.  To simplify kext debugging and lock-heat analysis, consider using lck_* locks with a per-driver lock group, as defined in kern/locks.h.
 360     @result Pointer to the allocated lock, or zero on failure. */
 361
 362 IOSimpleLock * IOSimpleLockAlloc( void );
 363
 364 /*! @function IOSimpleLockFree
 365     @abstract Frees a spin lock.
 366     @discussion Frees a lock allocated with IOSimpleLockAlloc.
 367     @param lock Pointer to the lock. */
 368
 369 void IOSimpleLockFree( IOSimpleLock * lock );
 370
 371 /*! @function IOSimpleLockGetMachLock
 372     @abstract Accessor to a Mach spin lock.
 373     @discussion Accessor to the Mach spin lock.
 374     @param lock Pointer to the allocated lock. */
 375
 376 lck_spin_t * IOSimpleLockGetMachLock( IOSimpleLock * lock);
 377
 378 /*! @function IOSimpleLockInit
 379     @abstract Initialize a spin lock.
 380     @discussion Initialize an embedded spin lock, to the unlocked state.
 381     @param lock Pointer to the lock. */
 382
 383 void IOSimpleLockInit( IOSimpleLock * lock );
 384
 385 /*! @function IOSimpleLockLock
 386     @abstract Lock a spin lock.
 387 @discussion Lock the spin lock. If the lock is held, spin waiting for its unlock. Spin locks disable preemption, cannot be held across any blocking operation, and should be held for very short periods. When used to synchronize between interrupt context and thread context they should be locked with interrupts disabled - IOSimpleLockLockDisableInterrupt() will do both. Locking the lock recursively from one thread will result in deadlock.
 388     @param lock Pointer to the lock. */
 389
 390 #ifdef  IOLOCKS_INLINE
 391 #define IOSimpleLockLock(l)     lck_spin_lock(l)
 392 #else
 393 void IOSimpleLockLock( IOSimpleLock * lock );
 394 #endif  /* !IOLOCKS_INLINE */
 395
 396
 397 /*! @function IOSimpleLockTryLock
 398     @abstract Attempt to lock a spin lock.
 399 @discussion Lock the spin lock if it is currently unlocked, and return true. If the lock is held, return false. Successful calls to IOSimpleLockTryLock should be balanced with calls to IOSimpleLockUnlock.
 400     @param lock Pointer to the lock.
 401     @result True if the lock was unlocked and is now locked by the caller, otherwise false. */
 402
 403 #ifdef  IOLOCKS_INLINE
 404 #define IOSimpleLockTryLock(l)  lck_spin_try_lock(l)
 405 #else
 406 boolean_t IOSimpleLockTryLock( IOSimpleLock * lock );
 407 #endif  /* !IOLOCKS_INLINE */
 408
 409 /*! @function IOSimpleLockUnlock
 410     @abstract Unlock a spin lock.
 411     @discussion Unlock the lock, and restore preemption. Results are undefined if the caller has not locked the lock.
 412     @param lock Pointer to the lock. */
 413
 414 #ifdef  IOLOCKS_INLINE
 415 #define IOSimpleLockUnlock(l)   lck_spin_unlock(l)
 416 #else
 417 void IOSimpleLockUnlock( IOSimpleLock * lock );
 418 #endif  /* !IOLOCKS_INLINE */
 419
 420 #ifdef XNU_KERNEL_PRIVATE
 421 /*! @enum     IOSimpleLockAssertState
 422  *  @abstract Used with IOSimpleLockAssert to assert the state of a lock.
 423  */
 424 typedef enum {
 425     kIOSimpleLockAssertOwned    = LCK_ASSERT_OWNED,
 426     kIOSimpleLockAssertNotOwned = LCK_ASSERT_NOTOWNED
 427 } IOSimpleLockAssertState;
 428
 429 #ifdef IOLOCKS_INLINE
 430 #define IOSimpleLockAssert(l, type) LCK_SPIN_ASSERT(l, type)
 431 #else
 432 /*! @function   IOSimpleLockAssert
 433  *  @abstract   Assert that spinlock is either held or not held by current thread.
 434  *  @discussion Call with either kIOSimpleLockAssertOwned or kIOSimpleLockAssertNotOwned.
 435  *  Panics the kernel if the lock is not owned if called with
 436  *  kIOSimpleLockAssertOwned and vice-versa.
 437  */
 438 void    IOSimpleLockAssert(IOSimpleLock *lock, IOSimpleLockAssertState type);
 439 #endif /* !IOLOCKS_INLINE */
 440 #endif /* !XNU_KERNEL_PRIVATE */
 441
 442 #if __LP64__
 443 typedef boolean_t IOInterruptState;
 444 #else
 445 typedef long int IOInterruptState;
 446 #endif
 447
 448 /*! @function IOSimpleLockLockDisableInterrupt
 449     @abstract Lock a spin lock.
 450     @discussion Lock the spin lock. If the lock is held, spin waiting for its unlock. Simple locks disable preemption, cannot be held across any blocking operation, and should be held for very short periods. When used to synchronize between interrupt context and thread context they should be locked with interrupts disabled - IOSimpleLockLockDisableInterrupt() will do both. Locking the lock recursively from one thread will result in deadlock.
 451     @param lock Pointer to the lock. */
 452
 453 static __inline__
 454 IOInterruptState IOSimpleLockLockDisableInterrupt( IOSimpleLock * lock )
 455 {
 456     IOInterruptState    state = ml_set_interrupts_enabled( false );
 457     IOSimpleLockLock( lock );
 458     return( state );
 459 }
 460
 461 /*! @function IOSimpleLockUnlockEnableInterrupt
 462     @abstract Unlock a spin lock, and restore interrupt state.
 463     @discussion Unlock the lock, and restore preemption and interrupts to the state as they were when the lock was taken. Results are undefined if the caller has not locked the lock.
 464     @param lock Pointer to the lock.
 465     @param state The interrupt state returned by IOSimpleLockLockDisableInterrupt() */
 466
 467 static __inline__
 468 void IOSimpleLockUnlockEnableInterrupt( IOSimpleLock * lock,
 469                                         IOInterruptState state )
 470 {
 471     IOSimpleLockUnlock( lock );
 472     ml_set_interrupts_enabled( state );
 473 }
 474
 475 #ifdef __cplusplus
 476 } /* extern "C" */
 477 #endif
 478
 479 #endif /* !__IOKIT_IOLOCKS_H */
 480