usr/src/uts/common/sys/mutex.h

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24
  25 #ifndef _SYS_MUTEX_H
  26 #define _SYS_MUTEX_H
  27
  28 #ifndef _ASM
  29 #include <sys/types.h>
  30 #endif
  31
  32 #ifdef  __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 #ifndef _ASM
  37
  38 /*
  39  * Public interface to mutual exclusion locks.  See mutex(9F) for details.
  40  *
  41  * The basic mutex type is MUTEX_ADAPTIVE, which is expected to be used
  42  * in almost all of the kernel.  MUTEX_SPIN provides interrupt blocking
  43  * and must be used in interrupt handlers above LOCK_LEVEL.  The iblock
  44  * cookie argument to mutex_init() encodes the interrupt level to block.
  45  * The iblock cookie must be NULL for adaptive locks.
  46  *
  47  * MUTEX_DEFAULT is the type usually specified (except in drivers) to
  48  * mutex_init().  It is identical to MUTEX_ADAPTIVE.
  49  *
  50  * MUTEX_DRIVER is always used by drivers.  mutex_init() converts this to
  51  * either MUTEX_ADAPTIVE or MUTEX_SPIN depending on the iblock cookie.
  52  *
  53  * Mutex statistics can be gathered on the fly, without rebooting or
  54  * recompiling the kernel, via the lockstat driver (lockstat(7D)).
  55  */
  56 typedef enum {
  57         MUTEX_ADAPTIVE = 0,     /* spin if owner is running, otherwise block */
  58         MUTEX_SPIN = 1,         /* block interrupts and spin */
  59         MUTEX_DRIVER = 4,       /* driver (DDI) mutex */
  60         MUTEX_DEFAULT = 6       /* kernel default mutex */
  61 } kmutex_type_t;
  62
  63 typedef struct mutex {
  64 #ifdef _LP64
  65         void    *_opaque[1];
  66 #else
  67         void    *_opaque[2];
  68 #endif
  69 } kmutex_t;
  70
  71 #ifdef _KERNEL
  72
  73 /*
  74  * A padded mutex, one per 64 byte cache line.  Use when false sharing is
  75  * an issue but beware of the extra memory it uses.  Consumers may want to
  76  * consider aligning their pad_mutex_t's to a cache line boundary as well.
  77  */
  78 typedef struct pad_mutex {
  79         kmutex_t        pad_mutex;
  80 #ifdef _LP64
  81         char            pad_pad[64 - sizeof (kmutex_t)];
  82 #endif
  83 } pad_mutex_t;
  84
  85 #define MUTEX_HELD(x)           (mutex_owned(x))
  86 #define MUTEX_NOT_HELD(x)       (!mutex_owned(x) || panicstr || quiesce_active)
  87
  88 extern  void    mutex_init(kmutex_t *, char *, kmutex_type_t, void *);
  89 extern  void    mutex_destroy(kmutex_t *);
  90 extern  void    mutex_enter(kmutex_t *);
  91 extern  int     mutex_tryenter(kmutex_t *);
  92 extern  void    mutex_exit(kmutex_t *);
  93 extern  int     mutex_owned(const kmutex_t *);
  94 extern  struct _kthread *mutex_owner(const kmutex_t *);
  95
  96 extern  ushort_t mutex_backoff_base;
  97 extern  uint_t mutex_backoff_cap;
  98 extern  ushort_t mutex_cap_factor;
  99 extern  uchar_t mutex_backoff_shift;
 100 extern  void (*mutex_lock_delay)(uint_t);
 101 extern  uint_t (*mutex_lock_backoff)(uint_t);
 102 extern  void (*mutex_delay)(void);
 103 extern  void mutex_delay_default(void);
 104 extern  void mutex_sync(void);
 105
 106 extern  void default_lock_delay(uint_t);
 107 extern  uint_t default_lock_backoff(uint_t);
 108
 109 #endif  /* _KERNEL */
 110
 111 #endif  /* _ASM */
 112
 113 #ifdef  __cplusplus
 114 }
 115 #endif
 116
 117 #endif  /* _SYS_MUTEX_H */