840680e601
instead of do {} while (0).
This makes them real void expressions, and they can be used anywhere
where a void function call can be used, for example in a conditional
operator.
Reviewed by: kib, mjg
Differential revision: https://reviews.freebsd.org/D32696
327 lines
11 KiB
C
327 lines
11 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2007 Attilio Rao <attilio@freebsd.org>
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* Copyright (c) 2001 Jason Evans <jasone@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice(s), this list of conditions and the following disclaimer as
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* the first lines of this file unmodified other than the possible
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* addition of one or more copyright notices.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice(s), this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _SYS_SX_H_
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#define _SYS_SX_H_
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#include <sys/_lock.h>
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#include <sys/_sx.h>
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#ifdef _KERNEL
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#include <sys/pcpu.h>
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#include <sys/lock_profile.h>
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#include <sys/lockstat.h>
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#include <machine/atomic.h>
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#endif
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/*
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* In general, the sx locks and rwlocks use very similar algorithms.
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* The main difference in the implementations is how threads are
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* blocked when a lock is unavailable. For this, sx locks use sleep
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* queues which do not support priority propagation, and rwlocks use
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* turnstiles which do.
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*
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* The sx_lock field consists of several fields. The low bit
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* indicates if the lock is locked with a shared or exclusive lock. A
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* value of 0 indicates an exclusive lock, and a value of 1 indicates
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* a shared lock. Bit 1 is a boolean indicating if there are any
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* threads waiting for a shared lock. Bit 2 is a boolean indicating
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* if there are any threads waiting for an exclusive lock. Bit 3 is a
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* boolean indicating if an exclusive lock is recursively held. The
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* rest of the variable's definition is dependent on the value of the
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* first bit. For an exclusive lock, it is a pointer to the thread
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* holding the lock, similar to the mtx_lock field of mutexes. For
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* shared locks, it is a count of read locks that are held.
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*
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* When the lock is not locked by any thread, it is encoded as a
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* shared lock with zero waiters.
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*/
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#define SX_LOCK_SHARED 0x01
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#define SX_LOCK_SHARED_WAITERS 0x02
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#define SX_LOCK_EXCLUSIVE_WAITERS 0x04
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#define SX_LOCK_WRITE_SPINNER 0x08
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#define SX_LOCK_RECURSED 0x10
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#define SX_LOCK_FLAGMASK \
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(SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \
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SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED | SX_LOCK_WRITE_SPINNER)
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#define SX_LOCK_WAITERS (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)
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#define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK)
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#define SX_SHARERS_SHIFT 5
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#define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT)
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#define SX_SHARERS_LOCK(x) \
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((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED)
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#define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT)
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#define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0)
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#define SX_LOCK_DESTROYED \
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(SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)
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#ifdef _KERNEL
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#define sx_recurse lock_object.lo_data
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#define SX_READ_VALUE(sx) ((sx)->sx_lock)
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#define lv_sx_owner(v) \
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((v & SX_LOCK_SHARED) ? NULL : (struct thread *)SX_OWNER(v))
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/*
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* Function prototipes. Routines that start with an underscore are not part
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* of the public interface and are wrappered with a macro.
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*/
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void sx_sysinit(void *arg);
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#define sx_init(sx, desc) sx_init_flags((sx), (desc), 0)
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void sx_init_flags(struct sx *sx, const char *description, int opts);
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void sx_destroy(struct sx *sx);
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int sx_try_slock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF);
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int sx_try_slock_(struct sx *sx, const char *file, int line);
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int sx_try_xlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF);
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int sx_try_xlock_(struct sx *sx, const char *file, int line);
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int sx_try_upgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF);
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int sx_try_upgrade_(struct sx *sx, const char *file, int line);
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void sx_downgrade_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF);
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void sx_downgrade_(struct sx *sx, const char *file, int line);
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int _sx_slock_int(struct sx *sx, int opts LOCK_FILE_LINE_ARG_DEF);
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int _sx_slock(struct sx *sx, int opts, const char *file, int line);
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int _sx_xlock(struct sx *sx, int opts, const char *file, int line);
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void _sx_sunlock_int(struct sx *sx LOCK_FILE_LINE_ARG_DEF);
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void _sx_sunlock(struct sx *sx, const char *file, int line);
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void _sx_xunlock(struct sx *sx, const char *file, int line);
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int _sx_xlock_hard(struct sx *sx, uintptr_t x, int opts LOCK_FILE_LINE_ARG_DEF);
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void _sx_xunlock_hard(struct sx *sx, uintptr_t x LOCK_FILE_LINE_ARG_DEF);
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#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
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void _sx_assert(const struct sx *sx, int what, const char *file, int line);
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#endif
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#ifdef DDB
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int sx_chain(struct thread *td, struct thread **ownerp);
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#endif
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struct sx_args {
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struct sx *sa_sx;
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const char *sa_desc;
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int sa_flags;
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};
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#define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \
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static struct sx_args name##_args = { \
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(sxa), \
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(desc), \
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(flags) \
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}; \
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SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
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sx_sysinit, &name##_args); \
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SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \
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sx_destroy, (sxa))
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#define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0)
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/*
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* Full lock operations that are suitable to be inlined in non-debug kernels.
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* If the lock can't be acquired or released trivially then the work is
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* deferred to 'tougher' functions.
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*/
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#if (LOCK_DEBUG == 0)
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/* Acquire an exclusive lock. */
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static __inline int
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__sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file,
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int line)
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{
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uintptr_t tid = (uintptr_t)td;
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uintptr_t v = SX_LOCK_UNLOCKED;
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int error = 0;
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if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__acquire) ||
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!atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid)))
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error = _sx_xlock_hard(sx, v, opts);
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return (error);
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}
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/* Release an exclusive lock. */
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static __inline void
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__sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line)
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{
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uintptr_t x = (uintptr_t)td;
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if (__predict_false(LOCKSTAT_PROFILE_ENABLED(sx__release) ||
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!atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, SX_LOCK_UNLOCKED)))
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_sx_xunlock_hard(sx, x);
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}
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#endif
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/*
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* Public interface for lock operations.
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*/
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#ifndef LOCK_DEBUG
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#error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>"
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#endif
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#if (LOCK_DEBUG > 0) || defined(SX_NOINLINE)
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#define sx_xlock_(sx, file, line) \
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(void)_sx_xlock((sx), 0, (file), (line))
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#define sx_xlock_sig_(sx, file, line) \
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_sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line))
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#define sx_xunlock_(sx, file, line) \
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_sx_xunlock((sx), (file), (line))
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#else
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#define sx_xlock_(sx, file, line) \
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(void)__sx_xlock((sx), curthread, 0, (file), (line))
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#define sx_xlock_sig_(sx, file, line) \
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__sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line))
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#define sx_xunlock_(sx, file, line) \
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__sx_xunlock((sx), curthread, (file), (line))
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#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */
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#if (LOCK_DEBUG > 0)
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#define sx_slock_(sx, file, line) \
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(void)_sx_slock((sx), 0, (file), (line))
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#define sx_slock_sig_(sx, file, line) \
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_sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line))
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#define sx_sunlock_(sx, file, line) \
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_sx_sunlock((sx), (file), (line))
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#define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE)
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#else
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#define sx_slock_(sx, file, line) \
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(void)_sx_slock_int((sx), 0)
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#define sx_slock_sig_(sx, file, line) \
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_sx_slock_int((sx), SX_INTERRUPTIBLE)
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#define sx_sunlock_(sx, file, line) \
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_sx_sunlock_int((sx))
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#define sx_try_slock(sx) sx_try_slock_int((sx))
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#define sx_try_xlock(sx) sx_try_xlock_int((sx))
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#define sx_try_upgrade(sx) sx_try_upgrade_int((sx))
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#define sx_downgrade(sx) sx_downgrade_int((sx))
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#endif
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#ifdef INVARIANTS
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#define sx_assert_(sx, what, file, line) \
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_sx_assert((sx), (what), (file), (line))
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#else
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#define sx_assert_(sx, what, file, line) (void)0
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#endif
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#define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__)
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/*
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* Return a pointer to the owning thread if the lock is exclusively
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* locked.
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*/
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#define sx_xholder(sx) \
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((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \
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(struct thread *)SX_OWNER((sx)->sx_lock))
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#define sx_xlocked(sx) \
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(((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \
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(uintptr_t)curthread)
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#define sx_unlock_(sx, file, line) __extension__ ({ \
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if (sx_xlocked(sx)) \
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sx_xunlock_(sx, file, line); \
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else \
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sx_sunlock_(sx, file, line); \
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(void)0; /* ensure void type for expression */ \
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})
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#define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE)
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#define sx_sleep(chan, sx, pri, wmesg, timo) \
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_sleep((chan), &(sx)->lock_object, (pri), (wmesg), \
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tick_sbt * (timo), 0, C_HARDCLOCK)
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/*
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* Options passed to sx_init_flags().
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*/
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#define SX_DUPOK 0x01
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#define SX_NOPROFILE 0x02
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#define SX_NOWITNESS 0x04
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#define SX_QUIET 0x08
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#define SX_RECURSE 0x20
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#define SX_NEW 0x40
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/*
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* Options passed to sx_*lock_hard().
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*/
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#define SX_INTERRUPTIBLE 0x40
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#if defined(INVARIANTS) || defined(INVARIANT_SUPPORT)
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#define SA_LOCKED LA_LOCKED
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#define SA_SLOCKED LA_SLOCKED
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#define SA_XLOCKED LA_XLOCKED
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#define SA_UNLOCKED LA_UNLOCKED
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#define SA_RECURSED LA_RECURSED
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#define SA_NOTRECURSED LA_NOTRECURSED
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/* Backwards compatibility. */
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#define SX_LOCKED LA_LOCKED
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#define SX_SLOCKED LA_SLOCKED
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#define SX_XLOCKED LA_XLOCKED
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#define SX_UNLOCKED LA_UNLOCKED
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#define SX_RECURSED LA_RECURSED
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#define SX_NOTRECURSED LA_NOTRECURSED
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#endif
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#endif /* _KERNEL */
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#ifdef _STANDALONE
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/* since we have no threads in the boot loader, trivially implement no-op version */
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#define sx_xlock(s) (1)
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#define sx_try_xlock(s) (1)
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#define sx_xunlock(s) (1)
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#define SX_DUPOK 0
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#define SX_NEW 0
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#define SX_NOWITNESS 0
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static __inline void
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sx_init_flags(struct sx *sx, const char *description, int opts)
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{
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}
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static __inline void
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sx_destroy(struct sx *sx)
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{
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}
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#endif /* _STANDALONE */
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#endif /* !_SYS_SX_H_ */
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