sx.h revision 315394
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/11/sys/sys/sx.h 315394 2017-03-16 08:29:09Z mjg $ 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 89258541Sattilio#define sx_recurse lock_object.lo_data 90258541Sattilio 91315341Smjg#define SX_READ_VALUE(sx) ((sx)->sx_lock) 92315341Smjg 93315341Smjg#define lv_sx_owner(v) \ 94315341Smjg ((v & SX_LOCK_SHARED) ? NULL : (struct thread *)SX_OWNER(v)) 95315341Smjg 96168191Sjhb/* 97168191Sjhb * Function prototipes. Routines that start with an underscore are not part 98168191Sjhb * of the public interface and are wrappered with a macro. 99168191Sjhb */ 10093672Sarrvoid sx_sysinit(void *arg); 101168191Sjhb#define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) 102168191Sjhbvoid sx_init_flags(struct sx *sx, const char *description, int opts); 10373782Sjasonevoid sx_destroy(struct sx *sx); 104227788Sattilioint sx_try_slock_(struct sx *sx, const char *file, int line); 105227788Sattilioint sx_try_xlock_(struct sx *sx, const char *file, int line); 106227788Sattilioint sx_try_upgrade_(struct sx *sx, const char *file, int line); 107227788Sattiliovoid sx_downgrade_(struct sx *sx, const char *file, int line); 108170149Sattilioint _sx_slock(struct sx *sx, int opts, const char *file, int line); 109170149Sattilioint _sx_xlock(struct sx *sx, int opts, const char *file, int line); 11074912Sjhbvoid _sx_sunlock(struct sx *sx, const char *file, int line); 11174912Sjhbvoid _sx_xunlock(struct sx *sx, const char *file, int line); 112315377Smjgint _sx_xlock_hard(struct sx *sx, uintptr_t v, uintptr_t tid, int opts, 113170149Sattilio const char *file, int line); 114168191Sjhbvoid _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int 115168191Sjhb line); 116161721Sjhb#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 117227588Spjdvoid _sx_assert(const struct sx *sx, int what, const char *file, int line); 11893688Sarr#endif 119161337Sjhb#ifdef DDB 120161337Sjhbint sx_chain(struct thread *td, struct thread **ownerp); 121161337Sjhb#endif 12293672Sarr 12393672Sarrstruct sx_args { 12493672Sarr struct sx *sa_sx; 12593672Sarr const char *sa_desc; 126219819Sjeff int sa_flags; 12793672Sarr}; 12893672Sarr 129219819Sjeff#define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \ 13093672Sarr static struct sx_args name##_args = { \ 131149739Sjhb (sxa), \ 132219819Sjeff (desc), \ 133219819Sjeff (flags) \ 13493672Sarr }; \ 13593672Sarr SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 136149739Sjhb sx_sysinit, &name##_args); \ 137149739Sjhb SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ 138149739Sjhb sx_destroy, (sxa)) 13973782Sjasone 140219819Sjeff#define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0) 141219819Sjeff 142168191Sjhb/* 143170149Sattilio * Full lock operations that are suitable to be inlined in non-debug kernels. 144170149Sattilio * If the lock can't be acquired or released trivially then the work is 145170149Sattilio * deferred to 'tougher' functions. 146170149Sattilio */ 147170149Sattilio 148315394Smjg#if (LOCK_DEBUG == 0) 149170149Sattilio/* Acquire an exclusive lock. */ 150170149Sattiliostatic __inline int 151170149Sattilio__sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, 152170149Sattilio int line) 153170149Sattilio{ 154170149Sattilio uintptr_t tid = (uintptr_t)td; 155315378Smjg uintptr_t v = SX_LOCK_UNLOCKED; 156170149Sattilio int error = 0; 157170149Sattilio 158315378Smjg if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__acquire) || 159315378Smjg !atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid))) 160315377Smjg error = _sx_xlock_hard(sx, v, tid, opts, file, line); 161170149Sattilio 162170149Sattilio return (error); 163170149Sattilio} 164170149Sattilio 165170149Sattilio/* Release an exclusive lock. */ 166170149Sattiliostatic __inline void 167170149Sattilio__sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) 168170149Sattilio{ 169170149Sattilio uintptr_t tid = (uintptr_t)td; 170170149Sattilio 171315378Smjg if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__release) || 172315378Smjg !atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED))) 173170149Sattilio _sx_xunlock_hard(sx, tid, file, line); 174170149Sattilio} 175315378Smjg#endif 176170149Sattilio 177170149Sattilio/* 178168191Sjhb * Public interface for lock operations. 179168191Sjhb */ 180168191Sjhb#ifndef LOCK_DEBUG 181168191Sjhb#error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>" 182168191Sjhb#endif 183168191Sjhb#if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) 184227788Sattilio#define sx_xlock_(sx, file, line) \ 185227788Sattilio (void)_sx_xlock((sx), 0, (file), (line)) 186227788Sattilio#define sx_xlock_sig_(sx, file, line) \ 187227788Sattilio _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line)) 188227788Sattilio#define sx_xunlock_(sx, file, line) \ 189227788Sattilio _sx_xunlock((sx), (file), (line)) 190168191Sjhb#else 191227788Sattilio#define sx_xlock_(sx, file, line) \ 192227788Sattilio (void)__sx_xlock((sx), curthread, 0, (file), (line)) 193227788Sattilio#define sx_xlock_sig_(sx, file, line) \ 194227788Sattilio __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line)) 195227788Sattilio#define sx_xunlock_(sx, file, line) \ 196227788Sattilio __sx_xunlock((sx), curthread, (file), (line)) 197315377Smjg#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ 198227788Sattilio#define sx_slock_(sx, file, line) \ 199315377Smjg (void)_sx_slock((sx), 0, (file), (line)) 200227788Sattilio#define sx_slock_sig_(sx, file, line) \ 201315377Smjg _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) 202227788Sattilio#define sx_sunlock_(sx, file, line) \ 203315377Smjg _sx_sunlock((sx), (file), (line)) 204227788Sattilio#define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE) 205227788Sattilio#define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE) 206227788Sattilio#define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE) 207227788Sattilio#define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE) 208227788Sattilio#ifdef INVARIANTS 209227788Sattilio#define sx_assert_(sx, what, file, line) \ 210227788Sattilio _sx_assert((sx), (what), (file), (line)) 211227788Sattilio#else 212227788Sattilio#define sx_assert_(sx, what, file, line) (void)0 213227788Sattilio#endif 214168191Sjhb 215227788Sattilio#define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE) 216227788Sattilio#define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE) 217227788Sattilio#define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE) 218227788Sattilio#define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE) 219227788Sattilio#define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE) 220227788Sattilio#define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE) 221227788Sattilio#define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__) 222227788Sattilio 223169776Sjhb/* 224169776Sjhb * Return a pointer to the owning thread if the lock is exclusively 225169776Sjhb * locked. 226169776Sjhb */ 227169776Sjhb#define sx_xholder(sx) \ 228169776Sjhb ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ 229169776Sjhb (struct thread *)SX_OWNER((sx)->sx_lock)) 230169776Sjhb 231168191Sjhb#define sx_xlocked(sx) \ 232168191Sjhb (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ 233168191Sjhb (uintptr_t)curthread) 234168191Sjhb 235227788Sattilio#define sx_unlock_(sx, file, line) do { \ 236159844Sjhb if (sx_xlocked(sx)) \ 237227788Sattilio sx_xunlock_(sx, file, line); \ 238157296Sjhb else \ 239227788Sattilio sx_sunlock_(sx, file, line); \ 240157296Sjhb} while (0) 241168191Sjhb 242227788Sattilio#define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE) 243227788Sattilio 244167387Sjhb#define sx_sleep(chan, sx, pri, wmesg, timo) \ 245247787Sdavide _sleep((chan), &(sx)->lock_object, (pri), (wmesg), \ 246247787Sdavide tick_sbt * (timo), 0, C_HARDCLOCK) 24774912Sjhb 248168191Sjhb/* 249168191Sjhb * Options passed to sx_init_flags(). 250168191Sjhb */ 251168191Sjhb#define SX_DUPOK 0x01 252168191Sjhb#define SX_NOPROFILE 0x02 253168191Sjhb#define SX_NOWITNESS 0x04 254168191Sjhb#define SX_QUIET 0x08 255193011Sattilio#define SX_NOADAPTIVE 0x10 256169769Sjhb#define SX_RECURSE 0x20 257275751Sdchagin#define SX_NEW 0x40 258168191Sjhb 259170149Sattilio/* 260170149Sattilio * Options passed to sx_*lock_hard(). 261170149Sattilio */ 262170149Sattilio#define SX_INTERRUPTIBLE 0x40 263170149Sattilio 26485412Sjhb#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) 265169780Sjhb#define SA_LOCKED LA_LOCKED 266169780Sjhb#define SA_SLOCKED LA_SLOCKED 267169780Sjhb#define SA_XLOCKED LA_XLOCKED 268169780Sjhb#define SA_UNLOCKED LA_UNLOCKED 269169780Sjhb#define SA_RECURSED LA_RECURSED 270169780Sjhb#define SA_NOTRECURSED LA_NOTRECURSED 271169780Sjhb 272298981Spfg/* Backwards compatibility. */ 27385388Sjhb#define SX_LOCKED LA_LOCKED 27485388Sjhb#define SX_SLOCKED LA_SLOCKED 27585388Sjhb#define SX_XLOCKED LA_XLOCKED 276125419Spjd#define SX_UNLOCKED LA_UNLOCKED 277168191Sjhb#define SX_RECURSED LA_RECURSED 278168191Sjhb#define SX_NOTRECURSED LA_NOTRECURSED 279125444Sbde#endif 28073863Sbmilekic 281125444Sbde#endif /* _KERNEL */ 282125444Sbde 283125444Sbde#endif /* !_SYS_SX_H_ */ 284