1139825Simp/*- 2168191Sjhb * Copyright (c) 2007 Attilio Rao <attilio@freebsd.org> 3168191Sjhb * Copyright (c) 2001 Jason Evans <jasone@freebsd.org> 4168191Sjhb * All rights reserved. 573782Sjasone * 673782Sjasone * Redistribution and use in source and binary forms, with or without 773782Sjasone * modification, are permitted provided that the following conditions 873782Sjasone * are met: 973782Sjasone * 1. Redistributions of source code must retain the above copyright 1073782Sjasone * notice(s), this list of conditions and the following disclaimer as 1173782Sjasone * the first lines of this file unmodified other than the possible 1273782Sjasone * addition of one or more copyright notices. 1373782Sjasone * 2. Redistributions in binary form must reproduce the above copyright 1473782Sjasone * notice(s), this list of conditions and the following disclaimer in the 1573782Sjasone * documentation and/or other materials provided with the distribution. 1673782Sjasone * 1773782Sjasone * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 1873782Sjasone * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 1973782Sjasone * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 2073782Sjasone * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 2173782Sjasone * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 2273782Sjasone * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 2373782Sjasone * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 2473782Sjasone * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2573782Sjasone * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2673782Sjasone * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 2773782Sjasone * DAMAGE. 2873782Sjasone * 2973782Sjasone * $FreeBSD: stable/10/sys/sys/sx.h 323870 2017-09-21 19:24:11Z marius $ 3073782Sjasone */ 3173782Sjasone 3273782Sjasone#ifndef _SYS_SX_H_ 3373782Sjasone#define _SYS_SX_H_ 3473782Sjasone 3583103Sjhb#include <sys/_lock.h> 36168191Sjhb#include <sys/_sx.h> 3773782Sjasone 38168191Sjhb#ifdef _KERNEL 39181682Sed#include <sys/pcpu.h> 40181682Sed#include <sys/lock_profile.h> 41192853Ssson#include <sys/lockstat.h> 42168191Sjhb#include <machine/atomic.h> 43168191Sjhb#endif 4473782Sjasone 45168191Sjhb/* 46168191Sjhb * In general, the sx locks and rwlocks use very similar algorithms. 47168191Sjhb * The main difference in the implementations is how threads are 48168191Sjhb * blocked when a lock is unavailable. For this, sx locks use sleep 49168191Sjhb * queues which do not support priority propagation, and rwlocks use 50168191Sjhb * turnstiles which do. 51168191Sjhb * 52168191Sjhb * The sx_lock field consists of several fields. The low bit 53168191Sjhb * indicates if the lock is locked with a shared or exclusive lock. A 54168191Sjhb * value of 0 indicates an exclusive lock, and a value of 1 indicates 55168191Sjhb * a shared lock. Bit 1 is a boolean indicating if there are any 56168191Sjhb * threads waiting for a shared lock. Bit 2 is a boolean indicating 57168191Sjhb * if there are any threads waiting for an exclusive lock. Bit 3 is a 58168191Sjhb * boolean indicating if an exclusive lock is recursively held. The 59168191Sjhb * rest of the variable's definition is dependent on the value of the 60168191Sjhb * first bit. For an exclusive lock, it is a pointer to the thread 61168191Sjhb * holding the lock, similar to the mtx_lock field of mutexes. For 62168191Sjhb * shared locks, it is a count of read locks that are held. 63168191Sjhb * 64168191Sjhb * When the lock is not locked by any thread, it is encoded as a 65168191Sjhb * shared lock with zero waiters. 66168191Sjhb */ 67168191Sjhb 68168191Sjhb#define SX_LOCK_SHARED 0x01 69168191Sjhb#define SX_LOCK_SHARED_WAITERS 0x02 70168191Sjhb#define SX_LOCK_EXCLUSIVE_WAITERS 0x04 71168191Sjhb#define SX_LOCK_RECURSED 0x08 72168191Sjhb#define SX_LOCK_FLAGMASK \ 73168191Sjhb (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \ 74168191Sjhb SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED) 75168191Sjhb 76168191Sjhb#define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK) 77168191Sjhb#define SX_SHARERS_SHIFT 4 78168191Sjhb#define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT) 79168191Sjhb#define SX_SHARERS_LOCK(x) \ 80168191Sjhb ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED) 81168191Sjhb#define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT) 82168191Sjhb 83168191Sjhb#define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0) 84169394Sjhb#define SX_LOCK_DESTROYED \ 85169394Sjhb (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS) 86168191Sjhb 8773782Sjasone#ifdef _KERNEL 88168191Sjhb 89168191Sjhb/* 90168191Sjhb * Function prototipes. Routines that start with an underscore are not part 91168191Sjhb * of the public interface and are wrappered with a macro. 92168191Sjhb */ 9393672Sarrvoid sx_sysinit(void *arg); 94168191Sjhb#define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) 95168191Sjhbvoid sx_init_flags(struct sx *sx, const char *description, int opts); 9673782Sjasonevoid sx_destroy(struct sx *sx); 97227788Sattilioint sx_try_slock_(struct sx *sx, const char *file, int line); 98227788Sattilioint sx_try_xlock_(struct sx *sx, const char *file, int line); 99227788Sattilioint sx_try_upgrade_(struct sx *sx, const char *file, int line); 100227788Sattiliovoid sx_downgrade_(struct sx *sx, const char *file, int line); 101170149Sattilioint _sx_slock(struct sx *sx, int opts, const char *file, int line); 102170149Sattilioint _sx_xlock(struct sx *sx, int opts, const char *file, int line); 10374912Sjhbvoid _sx_sunlock(struct sx *sx, const char *file, int line); 10474912Sjhbvoid _sx_xunlock(struct sx *sx, const char *file, int line); 105170149Sattilioint _sx_xlock_hard(struct sx *sx, uintptr_t tid, int opts, 106170149Sattilio const char *file, int line); 107170149Sattilioint _sx_slock_hard(struct sx *sx, int opts, const char *file, int line); 108168191Sjhbvoid _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int 109168191Sjhb line); 110168191Sjhbvoid _sx_sunlock_hard(struct sx *sx, const char *file, int line); 111161721Sjhb#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 112227588Spjdvoid _sx_assert(const struct sx *sx, int what, const char *file, int line); 11393688Sarr#endif 114161337Sjhb#ifdef DDB 115161337Sjhbint sx_chain(struct thread *td, struct thread **ownerp); 116161337Sjhb#endif 11793672Sarr 11893672Sarrstruct sx_args { 11993672Sarr struct sx *sa_sx; 12093672Sarr const char *sa_desc; 121219819Sjeff int sa_flags; 12293672Sarr}; 12393672Sarr 124219819Sjeff#define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \ 12593672Sarr static struct sx_args name##_args = { \ 126149739Sjhb (sxa), \ 127219819Sjeff (desc), \ 128219819Sjeff (flags) \ 12993672Sarr }; \ 13093672Sarr SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 131149739Sjhb sx_sysinit, &name##_args); \ 132149739Sjhb SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 133149739Sjhb sx_destroy, (sxa)) 13473782Sjasone 135219819Sjeff#define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0) 136219819Sjeff 137168191Sjhb/* 138170149Sattilio * Full lock operations that are suitable to be inlined in non-debug kernels. 139170149Sattilio * If the lock can't be acquired or released trivially then the work is 140170149Sattilio * deferred to 'tougher' functions. 141170149Sattilio */ 142170149Sattilio 143170149Sattilio/* Acquire an exclusive lock. */ 144170149Sattiliostatic __inline int 145170149Sattilio__sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, 146170149Sattilio int line) 147170149Sattilio{ 148170149Sattilio uintptr_t tid = (uintptr_t)td; 149170149Sattilio int error = 0; 150170149Sattilio 151310979Smjg if (sx->sx_lock != SX_LOCK_UNLOCKED || 152310979Smjg !atomic_cmpset_acq_ptr(&sx->sx_lock, SX_LOCK_UNLOCKED, tid)) 153170149Sattilio error = _sx_xlock_hard(sx, tid, opts, file, line); 154192853Ssson else 155192853Ssson LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_XLOCK_ACQUIRE, 156192853Ssson sx, 0, 0, file, line); 157170149Sattilio 158170149Sattilio return (error); 159170149Sattilio} 160170149Sattilio 161170149Sattilio/* Release an exclusive lock. */ 162170149Sattiliostatic __inline void 163170149Sattilio__sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) 164170149Sattilio{ 165170149Sattilio uintptr_t tid = (uintptr_t)td; 166170149Sattilio 167310979Smjg if (sx->sx_lock != tid || 168310979Smjg !atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED)) 169170149Sattilio _sx_xunlock_hard(sx, tid, file, line); 170170149Sattilio} 171170149Sattilio 172170149Sattilio/* Acquire a shared lock. */ 173170149Sattiliostatic __inline int 174170149Sattilio__sx_slock(struct sx *sx, int opts, const char *file, int line) 175170149Sattilio{ 176170149Sattilio uintptr_t x = sx->sx_lock; 177170149Sattilio int error = 0; 178170149Sattilio 179170149Sattilio if (!(x & SX_LOCK_SHARED) || 180170149Sattilio !atomic_cmpset_acq_ptr(&sx->sx_lock, x, x + SX_ONE_SHARER)) 181170149Sattilio error = _sx_slock_hard(sx, opts, file, line); 182174629Sjeff else 183192853Ssson LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_SLOCK_ACQUIRE, sx, 0, 184192853Ssson 0, file, line); 185170149Sattilio 186170149Sattilio return (error); 187170149Sattilio} 188170149Sattilio 189170149Sattilio/* 190170149Sattilio * Release a shared lock. We can just drop a single shared lock so 191170149Sattilio * long as we aren't trying to drop the last shared lock when other 192170149Sattilio * threads are waiting for an exclusive lock. This takes advantage of 193170149Sattilio * the fact that an unlocked lock is encoded as a shared lock with a 194170149Sattilio * count of 0. 195170149Sattilio */ 196170149Sattiliostatic __inline void 197170149Sattilio__sx_sunlock(struct sx *sx, const char *file, int line) 198170149Sattilio{ 199170149Sattilio uintptr_t x = sx->sx_lock; 200170149Sattilio 201170149Sattilio if (x == (SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS) || 202197643Sattilio !atomic_cmpset_rel_ptr(&sx->sx_lock, x, x - SX_ONE_SHARER)) 203170149Sattilio _sx_sunlock_hard(sx, file, line); 204170149Sattilio} 205170149Sattilio 206170149Sattilio/* 207168191Sjhb * Public interface for lock operations. 208168191Sjhb */ 209168191Sjhb#ifndef LOCK_DEBUG 210168191Sjhb#error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>" 211168191Sjhb#endif 212168191Sjhb#if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) 213227788Sattilio#define sx_xlock_(sx, file, line) \ 214227788Sattilio (void)_sx_xlock((sx), 0, (file), (line)) 215227788Sattilio#define sx_xlock_sig_(sx, file, line) \ 216227788Sattilio _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line)) 217227788Sattilio#define sx_xunlock_(sx, file, line) \ 218227788Sattilio _sx_xunlock((sx), (file), (line)) 219227788Sattilio#define sx_slock_(sx, file, line) \ 220227788Sattilio (void)_sx_slock((sx), 0, (file), (line)) 221227788Sattilio#define sx_slock_sig_(sx, file, line) \ 222227788Sattilio _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) 223227788Sattilio#define sx_sunlock_(sx, file, line) \ 224227788Sattilio _sx_sunlock((sx), (file), (line)) 225168191Sjhb#else 226227788Sattilio#define sx_xlock_(sx, file, line) \ 227227788Sattilio (void)__sx_xlock((sx), curthread, 0, (file), (line)) 228227788Sattilio#define sx_xlock_sig_(sx, file, line) \ 229227788Sattilio __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line)) 230227788Sattilio#define sx_xunlock_(sx, file, line) \ 231227788Sattilio __sx_xunlock((sx), curthread, (file), (line)) 232227788Sattilio#define sx_slock_(sx, file, line) \ 233227788Sattilio (void)__sx_slock((sx), 0, (file), (line)) 234227788Sattilio#define sx_slock_sig_(sx, file, line) \ 235227788Sattilio __sx_slock((sx), SX_INTERRUPTIBLE, (file), (line)) 236227788Sattilio#define sx_sunlock_(sx, file, line) \ 237227788Sattilio __sx_sunlock((sx), (file), (line)) 238168191Sjhb#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ 239227788Sattilio#define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE) 240227788Sattilio#define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE) 241227788Sattilio#define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE) 242227788Sattilio#define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE) 243227788Sattilio#ifdef INVARIANTS 244227788Sattilio#define sx_assert_(sx, what, file, line) \ 245227788Sattilio _sx_assert((sx), (what), (file), (line)) 246227788Sattilio#else 247227788Sattilio#define sx_assert_(sx, what, file, line) (void)0 248227788Sattilio#endif 249168191Sjhb 250227788Sattilio#define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE) 251227788Sattilio#define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE) 252227788Sattilio#define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE) 253227788Sattilio#define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE) 254227788Sattilio#define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE) 255227788Sattilio#define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE) 256227788Sattilio#define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__) 257227788Sattilio 258169776Sjhb/* 259169776Sjhb * Return a pointer to the owning thread if the lock is exclusively 260169776Sjhb * locked. 261169776Sjhb */ 262169776Sjhb#define sx_xholder(sx) \ 263169776Sjhb ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ 264169776Sjhb (struct thread *)SX_OWNER((sx)->sx_lock)) 265169776Sjhb 266168191Sjhb#define sx_xlocked(sx) \ 267168191Sjhb (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ 268168191Sjhb (uintptr_t)curthread) 269168191Sjhb 270227788Sattilio#define sx_unlock_(sx, file, line) do { \ 271159844Sjhb if (sx_xlocked(sx)) \ 272227788Sattilio sx_xunlock_(sx, file, line); \ 273157296Sjhb else \ 274227788Sattilio sx_sunlock_(sx, file, line); \ 275157296Sjhb} while (0) 276168191Sjhb 277227788Sattilio#define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE) 278227788Sattilio 279167387Sjhb#define sx_sleep(chan, sx, pri, wmesg, timo) \ 280247787Sdavide _sleep((chan), &(sx)->lock_object, (pri), (wmesg), \ 281247787Sdavide tick_sbt * (timo), 0, C_HARDCLOCK) 28274912Sjhb 283168191Sjhb/* 284168191Sjhb * Options passed to sx_init_flags(). 285168191Sjhb */ 286168191Sjhb#define SX_DUPOK 0x01 287168191Sjhb#define SX_NOPROFILE 0x02 288168191Sjhb#define SX_NOWITNESS 0x04 289168191Sjhb#define SX_QUIET 0x08 290193011Sattilio#define SX_NOADAPTIVE 0x10 291169769Sjhb#define SX_RECURSE 0x20 292323870Smarius#define SX_NEW 0x40 293168191Sjhb 294170149Sattilio/* 295170149Sattilio * Options passed to sx_*lock_hard(). 296170149Sattilio */ 297170149Sattilio#define SX_INTERRUPTIBLE 0x40 298170149Sattilio 29985412Sjhb#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 300169780Sjhb#define SA_LOCKED LA_LOCKED 301169780Sjhb#define SA_SLOCKED LA_SLOCKED 302169780Sjhb#define SA_XLOCKED LA_XLOCKED 303169780Sjhb#define SA_UNLOCKED LA_UNLOCKED 304169780Sjhb#define SA_RECURSED LA_RECURSED 305169780Sjhb#define SA_NOTRECURSED LA_NOTRECURSED 306169780Sjhb 307300060Spfg/* Backwards compatibility. */ 30885388Sjhb#define SX_LOCKED LA_LOCKED 30985388Sjhb#define SX_SLOCKED LA_SLOCKED 31085388Sjhb#define SX_XLOCKED LA_XLOCKED 311125419Spjd#define SX_UNLOCKED LA_UNLOCKED 312168191Sjhb#define SX_RECURSED LA_RECURSED 313168191Sjhb#define SX_NOTRECURSED LA_NOTRECURSED 314125444Sbde#endif 31573863Sbmilekic 316125444Sbde#endif /* _KERNEL */ 317125444Sbde 318125444Sbde#endif /* !_SYS_SX_H_ */ 319