Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/sys/sx.h
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1 /*- 2 * Copyright (c) 2007 Attilio Rao <attilio@freebsd.org> 3 * Copyright (c) 2001 Jason Evans <jasone@freebsd.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice(s), this list of conditions and the following disclaimer as 11 * the first lines of this file unmodified other than the possible 12 * addition of one or more copyright notices. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice(s), this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 23 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 24 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 27 * DAMAGE. 28 * 29 * $FreeBSD: releng/11.2/sys/sys/sx.h 331722 2018-03-29 02:50:57Z eadler $ 30 */ 31 32 #ifndef _SYS_SX_H_ 33 #define _SYS_SX_H_ 34 35 #include <sys/_lock.h> 36 #include <sys/_sx.h> 37 38 #ifdef _KERNEL 39 #include <sys/pcpu.h> 40 #include <sys/lock_profile.h> 41 #include <sys/lockstat.h> 42 #include <machine/atomic.h> 43 #endif 44 45 /* 46 * In general, the sx locks and rwlocks use very similar algorithms. 47 * The main difference in the implementations is how threads are 48 * blocked when a lock is unavailable. For this, sx locks use sleep 49 * queues which do not support priority propagation, and rwlocks use 50 * turnstiles which do. 51 * 52 * The sx_lock field consists of several fields. The low bit 53 * indicates if the lock is locked with a shared or exclusive lock. A 54 * value of 0 indicates an exclusive lock, and a value of 1 indicates 55 * a shared lock. Bit 1 is a boolean indicating if there are any 56 * threads waiting for a shared lock. Bit 2 is a boolean indicating 57 * if there are any threads waiting for an exclusive lock. Bit 3 is a 58 * boolean indicating if an exclusive lock is recursively held. The 59 * rest of the variable's definition is dependent on the value of the 60 * first bit. For an exclusive lock, it is a pointer to the thread 61 * holding the lock, similar to the mtx_lock field of mutexes. For 62 * shared locks, it is a count of read locks that are held. 63 * 64 * When the lock is not locked by any thread, it is encoded as a 65 * shared lock with zero waiters. 66 */ 67 68 #define SX_LOCK_SHARED 0x01 69 #define SX_LOCK_SHARED_WAITERS 0x02 70 #define SX_LOCK_EXCLUSIVE_WAITERS 0x04 71 #define SX_LOCK_RECURSED 0x08 72 #define SX_LOCK_FLAGMASK \ 73 (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \ 74 SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED) 75 76 #define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK) 77 #define SX_SHARERS_SHIFT 4 78 #define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT) 79 #define SX_SHARERS_LOCK(x) \ 80 ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED) 81 #define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT) 82 83 #define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0) 84 #define SX_LOCK_DESTROYED \ 85 (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS) 86 87 #ifdef _KERNEL 88 89 #define sx_recurse lock_object.lo_data 90 91 #define SX_READ_VALUE(sx) ((sx)->sx_lock) 92 93 #define lv_sx_owner(v) \ 94 ((v & SX_LOCK_SHARED) ? NULL : (struct thread *)SX_OWNER(v)) 95 96 /* 97 * Function prototipes. Routines that start with an underscore are not part 98 * of the public interface and are wrappered with a macro. 99 */ 100 void sx_sysinit(void *arg); 101 #define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) 102 void sx_init_flags(struct sx *sx, const char *description, int opts); 103 void sx_destroy(struct sx *sx); 104 int sx_try_slock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 105 int sx_try_slock_(struct sx *sx, const char *file, int line); 106 int sx_try_xlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 107 int sx_try_xlock_(struct sx *sx, const char *file, int line); 108 int sx_try_upgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 109 int sx_try_upgrade_(struct sx *sx, const char *file, int line); 110 void sx_downgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 111 void sx_downgrade_(struct sx *sx, const char *file, int line); 112 int _sx_slock_int(struct sx *sx, int opts LOCK_FILE_LINE_ARG_DEF); 113 int _sx_slock(struct sx *sx, int opts, const char *file, int line); 114 int _sx_xlock(struct sx *sx, int opts, const char *file, int line); 115 void _sx_sunlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 116 void _sx_sunlock(struct sx *sx, const char *file, int line); 117 void _sx_xunlock(struct sx *sx, const char *file, int line); 118 int _sx_xlock_hard(struct sx *sx, uintptr_t x, int opts LOCK_FILE_LINE_ARG_DEF); 119 void _sx_xunlock_hard(struct sx *sx, uintptr_t x LOCK_FILE_LINE_ARG_DEF); 120 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 121 void _sx_assert(const struct sx *sx, int what, const char *file, int line); 122 #endif 123 #ifdef DDB 124 int sx_chain(struct thread *td, struct thread **ownerp); 125 #endif 126 127 struct sx_args { 128 struct sx *sa_sx; 129 const char *sa_desc; 130 int sa_flags; 131 }; 132 133 #define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \ 134 static struct sx_args name##_args = { \ 135 (sxa), \ 136 (desc), \ 137 (flags) \ 138 }; \ 139 SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 140 sx_sysinit, &name##_args); \ 141 SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 142 sx_destroy, (sxa)) 143 144 #define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0) 145 146 /* 147 * Full lock operations that are suitable to be inlined in non-debug kernels. 148 * If the lock can't be acquired or released trivially then the work is 149 * deferred to 'tougher' functions. 150 */ 151 152 #if (LOCK_DEBUG == 0) 153 /* Acquire an exclusive lock. */ 154 static __inline int 155 __sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, 156 int line) 157 { 158 uintptr_t tid = (uintptr_t)td; 159 uintptr_t v = SX_LOCK_UNLOCKED; 160 int error = 0; 161 162 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__acquire) || 163 !atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid))) 164 error = _sx_xlock_hard(sx, v, opts); 165 166 return (error); 167 } 168 169 /* Release an exclusive lock. */ 170 static __inline void 171 __sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) 172 { 173 uintptr_t x = (uintptr_t)td; 174 175 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__release) || 176 !atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, SX_LOCK_UNLOCKED))) 177 _sx_xunlock_hard(sx, x); 178 } 179 #endif 180 181 /* 182 * Public interface for lock operations. 183 */ 184 #ifndef LOCK_DEBUG 185 #error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>" 186 #endif 187 #if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) 188 #define sx_xlock_(sx, file, line) \ 189 (void)_sx_xlock((sx), 0, (file), (line)) 190 #define sx_xlock_sig_(sx, file, line) \ 191 _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line)) 192 #define sx_xunlock_(sx, file, line) \ 193 _sx_xunlock((sx), (file), (line)) 194 #else 195 #define sx_xlock_(sx, file, line) \ 196 (void)__sx_xlock((sx), curthread, 0, (file), (line)) 197 #define sx_xlock_sig_(sx, file, line) \ 198 __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line)) 199 #define sx_xunlock_(sx, file, line) \ 200 __sx_xunlock((sx), curthread, (file), (line)) 201 #endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ 202 #if (LOCK_DEBUG > 0) 203 #define sx_slock_(sx, file, line) \ 204 (void)_sx_slock((sx), 0, (file), (line)) 205 #define sx_slock_sig_(sx, file, line) \ 206 _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) 207 #define sx_sunlock_(sx, file, line) \ 208 _sx_sunlock((sx), (file), (line)) 209 #define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE) 210 #define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE) 211 #define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE) 212 #define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE) 213 #else 214 #define sx_slock_(sx, file, line) \ 215 (void)_sx_slock_int((sx), 0) 216 #define sx_slock_sig_(sx, file, line) \ 217 _sx_slock_int((sx), SX_INTERRUPTIBLE) 218 #define sx_sunlock_(sx, file, line) \ 219 _sx_sunlock_int((sx)) 220 #define sx_try_slock(sx) sx_try_slock_int((sx)) 221 #define sx_try_xlock(sx) sx_try_xlock_int((sx)) 222 #define sx_try_upgrade(sx) sx_try_upgrade_int((sx)) 223 #define sx_downgrade(sx) sx_downgrade_int((sx)) 224 #endif 225 #ifdef INVARIANTS 226 #define sx_assert_(sx, what, file, line) \ 227 _sx_assert((sx), (what), (file), (line)) 228 #else 229 #define sx_assert_(sx, what, file, line) (void)0 230 #endif 231 232 #define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE) 233 #define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE) 234 #define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE) 235 #define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE) 236 #define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE) 237 #define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE) 238 #define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__) 239 240 /* 241 * Return a pointer to the owning thread if the lock is exclusively 242 * locked. 243 */ 244 #define sx_xholder(sx) \ 245 ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ 246 (struct thread *)SX_OWNER((sx)->sx_lock)) 247 248 #define sx_xlocked(sx) \ 249 (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ 250 (uintptr_t)curthread) 251 252 #define sx_unlock_(sx, file, line) do { \ 253 if (sx_xlocked(sx)) \ 254 sx_xunlock_(sx, file, line); \ 255 else \ 256 sx_sunlock_(sx, file, line); \ 257 } while (0) 258 259 #define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE) 260 261 #define sx_sleep(chan, sx, pri, wmesg, timo) \ 262 _sleep((chan), &(sx)->lock_object, (pri), (wmesg), \ 263 tick_sbt * (timo), 0, C_HARDCLOCK) 264 265 /* 266 * Options passed to sx_init_flags(). 267 */ 268 #define SX_DUPOK 0x01 269 #define SX_NOPROFILE 0x02 270 #define SX_NOWITNESS 0x04 271 #define SX_QUIET 0x08 272 #define SX_NOADAPTIVE 0x10 273 #define SX_RECURSE 0x20 274 #define SX_NEW 0x40 275 276 /* 277 * Options passed to sx_*lock_hard(). 278 */ 279 #define SX_INTERRUPTIBLE 0x40 280 281 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 282 #define SA_LOCKED LA_LOCKED 283 #define SA_SLOCKED LA_SLOCKED 284 #define SA_XLOCKED LA_XLOCKED 285 #define SA_UNLOCKED LA_UNLOCKED 286 #define SA_RECURSED LA_RECURSED 287 #define SA_NOTRECURSED LA_NOTRECURSED 288 289 /* Backwards compatibility. */ 290 #define SX_LOCKED LA_LOCKED 291 #define SX_SLOCKED LA_SLOCKED 292 #define SX_XLOCKED LA_XLOCKED 293 #define SX_UNLOCKED LA_UNLOCKED 294 #define SX_RECURSED LA_RECURSED 295 #define SX_NOTRECURSED LA_NOTRECURSED 296 #endif 297 298 #endif /* _KERNEL */ 299 300 #endif /* !_SYS_SX_H_ */
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