sx.h revision 330897
1/*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2007 Attilio Rao <attilio@freebsd.org> 5 * Copyright (c) 2001 Jason Evans <jasone@freebsd.org> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice(s), this list of conditions and the following disclaimer as 13 * the first lines of this file unmodified other than the possible 14 * addition of one or more copyright notices. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice(s), this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 20 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 21 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 22 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 23 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 24 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 25 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 26 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 29 * DAMAGE. 30 * 31 * $FreeBSD: stable/11/sys/sys/sx.h 330897 2018-03-14 03:19:51Z eadler $ 32 */ 33 34#ifndef _SYS_SX_H_ 35#define _SYS_SX_H_ 36 37#include <sys/_lock.h> 38#include <sys/_sx.h> 39 40#ifdef _KERNEL 41#include <sys/pcpu.h> 42#include <sys/lock_profile.h> 43#include <sys/lockstat.h> 44#include <machine/atomic.h> 45#endif 46 47/* 48 * In general, the sx locks and rwlocks use very similar algorithms. 49 * The main difference in the implementations is how threads are 50 * blocked when a lock is unavailable. For this, sx locks use sleep 51 * queues which do not support priority propagation, and rwlocks use 52 * turnstiles which do. 53 * 54 * The sx_lock field consists of several fields. The low bit 55 * indicates if the lock is locked with a shared or exclusive lock. A 56 * value of 0 indicates an exclusive lock, and a value of 1 indicates 57 * a shared lock. Bit 1 is a boolean indicating if there are any 58 * threads waiting for a shared lock. Bit 2 is a boolean indicating 59 * if there are any threads waiting for an exclusive lock. Bit 3 is a 60 * boolean indicating if an exclusive lock is recursively held. The 61 * rest of the variable's definition is dependent on the value of the 62 * first bit. For an exclusive lock, it is a pointer to the thread 63 * holding the lock, similar to the mtx_lock field of mutexes. For 64 * shared locks, it is a count of read locks that are held. 65 * 66 * When the lock is not locked by any thread, it is encoded as a 67 * shared lock with zero waiters. 68 */ 69 70#define SX_LOCK_SHARED 0x01 71#define SX_LOCK_SHARED_WAITERS 0x02 72#define SX_LOCK_EXCLUSIVE_WAITERS 0x04 73#define SX_LOCK_RECURSED 0x08 74#define SX_LOCK_FLAGMASK \ 75 (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \ 76 SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED) 77 78#define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK) 79#define SX_SHARERS_SHIFT 4 80#define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT) 81#define SX_SHARERS_LOCK(x) \ 82 ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED) 83#define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT) 84 85#define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0) 86#define SX_LOCK_DESTROYED \ 87 (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS) 88 89#ifdef _KERNEL 90 91#define sx_recurse lock_object.lo_data 92 93#define SX_READ_VALUE(sx) ((sx)->sx_lock) 94 95#define lv_sx_owner(v) \ 96 ((v & SX_LOCK_SHARED) ? NULL : (struct thread *)SX_OWNER(v)) 97 98/* 99 * Function prototipes. Routines that start with an underscore are not part 100 * of the public interface and are wrappered with a macro. 101 */ 102void sx_sysinit(void *arg); 103#define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) 104void sx_init_flags(struct sx *sx, const char *description, int opts); 105void sx_destroy(struct sx *sx); 106int sx_try_slock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 107int sx_try_slock_(struct sx *sx, const char *file, int line); 108int sx_try_xlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 109int sx_try_xlock_(struct sx *sx, const char *file, int line); 110int sx_try_upgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 111int sx_try_upgrade_(struct sx *sx, const char *file, int line); 112void sx_downgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 113void sx_downgrade_(struct sx *sx, const char *file, int line); 114int _sx_slock_int(struct sx *sx, int opts LOCK_FILE_LINE_ARG_DEF); 115int _sx_slock(struct sx *sx, int opts, const char *file, int line); 116int _sx_xlock(struct sx *sx, int opts, const char *file, int line); 117void _sx_sunlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF); 118void _sx_sunlock(struct sx *sx, const char *file, int line); 119void _sx_xunlock(struct sx *sx, const char *file, int line); 120int _sx_xlock_hard(struct sx *sx, uintptr_t x, int opts LOCK_FILE_LINE_ARG_DEF); 121void _sx_xunlock_hard(struct sx *sx, uintptr_t x LOCK_FILE_LINE_ARG_DEF); 122#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 123void _sx_assert(const struct sx *sx, int what, const char *file, int line); 124#endif 125#ifdef DDB 126int sx_chain(struct thread *td, struct thread **ownerp); 127#endif 128 129struct sx_args { 130 struct sx *sa_sx; 131 const char *sa_desc; 132 int sa_flags; 133}; 134 135#define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \ 136 static struct sx_args name##_args = { \ 137 (sxa), \ 138 (desc), \ 139 (flags) \ 140 }; \ 141 SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 142 sx_sysinit, &name##_args); \ 143 SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 144 sx_destroy, (sxa)) 145 146#define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0) 147 148/* 149 * Full lock operations that are suitable to be inlined in non-debug kernels. 150 * If the lock can't be acquired or released trivially then the work is 151 * deferred to 'tougher' functions. 152 */ 153 154#if (LOCK_DEBUG == 0) 155/* Acquire an exclusive lock. */ 156static __inline int 157__sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, 158 int line) 159{ 160 uintptr_t tid = (uintptr_t)td; 161 uintptr_t v = SX_LOCK_UNLOCKED; 162 int error = 0; 163 164 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__acquire) || 165 !atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid))) 166 error = _sx_xlock_hard(sx, v, opts); 167 168 return (error); 169} 170 171/* Release an exclusive lock. */ 172static __inline void 173__sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) 174{ 175 uintptr_t x = (uintptr_t)td; 176 177 if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__release) || 178 !atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, SX_LOCK_UNLOCKED))) 179 _sx_xunlock_hard(sx, x); 180} 181#endif 182 183/* 184 * Public interface for lock operations. 185 */ 186#ifndef LOCK_DEBUG 187#error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>" 188#endif 189#if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) 190#define sx_xlock_(sx, file, line) \ 191 (void)_sx_xlock((sx), 0, (file), (line)) 192#define sx_xlock_sig_(sx, file, line) \ 193 _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line)) 194#define sx_xunlock_(sx, file, line) \ 195 _sx_xunlock((sx), (file), (line)) 196#else 197#define sx_xlock_(sx, file, line) \ 198 (void)__sx_xlock((sx), curthread, 0, (file), (line)) 199#define sx_xlock_sig_(sx, file, line) \ 200 __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line)) 201#define sx_xunlock_(sx, file, line) \ 202 __sx_xunlock((sx), curthread, (file), (line)) 203#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ 204#if (LOCK_DEBUG > 0) 205#define sx_slock_(sx, file, line) \ 206 (void)_sx_slock((sx), 0, (file), (line)) 207#define sx_slock_sig_(sx, file, line) \ 208 _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) 209#define sx_sunlock_(sx, file, line) \ 210 _sx_sunlock((sx), (file), (line)) 211#define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE) 212#define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE) 213#define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE) 214#define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE) 215#else 216#define sx_slock_(sx, file, line) \ 217 (void)_sx_slock_int((sx), 0) 218#define sx_slock_sig_(sx, file, line) \ 219 _sx_slock_int((sx), SX_INTERRUPTIBLE) 220#define sx_sunlock_(sx, file, line) \ 221 _sx_sunlock_int((sx)) 222#define sx_try_slock(sx) sx_try_slock_int((sx)) 223#define sx_try_xlock(sx) sx_try_xlock_int((sx)) 224#define sx_try_upgrade(sx) sx_try_upgrade_int((sx)) 225#define sx_downgrade(sx) sx_downgrade_int((sx)) 226#endif 227#ifdef INVARIANTS 228#define sx_assert_(sx, what, file, line) \ 229 _sx_assert((sx), (what), (file), (line)) 230#else 231#define sx_assert_(sx, what, file, line) (void)0 232#endif 233 234#define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE) 235#define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE) 236#define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE) 237#define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE) 238#define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE) 239#define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE) 240#define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__) 241 242/* 243 * Return a pointer to the owning thread if the lock is exclusively 244 * locked. 245 */ 246#define sx_xholder(sx) \ 247 ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ 248 (struct thread *)SX_OWNER((sx)->sx_lock)) 249 250#define sx_xlocked(sx) \ 251 (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ 252 (uintptr_t)curthread) 253 254#define sx_unlock_(sx, file, line) do { \ 255 if (sx_xlocked(sx)) \ 256 sx_xunlock_(sx, file, line); \ 257 else \ 258 sx_sunlock_(sx, file, line); \ 259} while (0) 260 261#define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE) 262 263#define sx_sleep(chan, sx, pri, wmesg, timo) \ 264 _sleep((chan), &(sx)->lock_object, (pri), (wmesg), \ 265 tick_sbt * (timo), 0, C_HARDCLOCK) 266 267/* 268 * Options passed to sx_init_flags(). 269 */ 270#define SX_DUPOK 0x01 271#define SX_NOPROFILE 0x02 272#define SX_NOWITNESS 0x04 273#define SX_QUIET 0x08 274#define SX_NOADAPTIVE 0x10 275#define SX_RECURSE 0x20 276#define SX_NEW 0x40 277 278/* 279 * Options passed to sx_*lock_hard(). 280 */ 281#define SX_INTERRUPTIBLE 0x40 282 283#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 284#define SA_LOCKED LA_LOCKED 285#define SA_SLOCKED LA_SLOCKED 286#define SA_XLOCKED LA_XLOCKED 287#define SA_UNLOCKED LA_UNLOCKED 288#define SA_RECURSED LA_RECURSED 289#define SA_NOTRECURSED LA_NOTRECURSED 290 291/* Backwards compatibility. */ 292#define SX_LOCKED LA_LOCKED 293#define SX_SLOCKED LA_SLOCKED 294#define SX_XLOCKED LA_XLOCKED 295#define SX_UNLOCKED LA_UNLOCKED 296#define SX_RECURSED LA_RECURSED 297#define SX_NOTRECURSED LA_NOTRECURSED 298#endif 299 300#endif /* _KERNEL */ 301 302#endif /* !_SYS_SX_H_ */ 303