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192846463a
- Introduce lock classes and lock objects. Each lock class specifies a
name and set of flags (or properties) shared by all locks of a given
type. Currently there are three lock classes: spin mutexes, sleep
mutexes, and sx locks. A lock object specifies properties of an
additional lock along with a lock name and all of the extra stuff needed
to make witness work with a given lock. This abstract lock stuff is
defined in sys/lock.h. The lockmgr constants, types, and prototypes have
been moved to sys/lockmgr.h. For temporary backwards compatability,
sys/lock.h includes sys/lockmgr.h.
- Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin
locks held. By making this per-cpu, we do not have to jump through
magic hoops to deal with sched_lock changing ownership during context
switches.
- Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with
proc->p_sleeplocks, which is a list of held sleep locks including sleep
mutexes and sx locks.
- Add helper macros for logging lock events via the KTR_LOCK KTR logging
level so that the log messages are consistent.
- Add some new flags that can be passed to mtx_init():
- MTX_NOWITNESS - specifies that this lock should be ignored by witness.
This is used for the mutex that blocks a sx lock for example.
- MTX_QUIET - this is not new, but you can pass this to mtx_init() now
and no events will be logged for this lock, so that one doesn't have
to change all the individual mtx_lock/unlock() operations.
- All lock objects maintain an initialized flag. Use this flag to export
a mtx_initialized() macro that can be safely called from drivers. Also,
we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness
performs the corresponding checks using the initialized flag.
- The lock order reversal messages have been improved to output slightly
more accurate file and line numbers.
102 lines
3.8 KiB
C
102 lines
3.8 KiB
C
/*
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* Copyright (C) 2001 Jason Evans <jasone@freebsd.org>. 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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#ifndef LOCORE
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#include <sys/lock.h> /* XXX */
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#include <sys/mutex.h> /* XXX */
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#include <sys/condvar.h> /* XXX */
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struct lock_object;
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struct sx {
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struct lock_object sx_object; /* Common lock properties. */
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struct mtx sx_lock; /* General protection lock. */
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int sx_cnt; /* -1: xlock, > 0: slock count. */
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struct cv sx_shrd_cv; /* slock waiters. */
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int sx_shrd_wcnt; /* Number of slock waiters. */
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struct cv sx_excl_cv; /* xlock waiters. */
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int sx_excl_wcnt; /* Number of xlock waiters. */
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struct proc *sx_xholder; /* Thread presently holding xlock. */
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};
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#ifdef _KERNEL
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void sx_init(struct sx *sx, const char *description);
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void sx_destroy(struct sx *sx);
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void _sx_slock(struct sx *sx, const char *file, int line);
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void _sx_xlock(struct sx *sx, const char *file, int line);
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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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#define sx_slock(sx) _sx_slock((sx), __FILE__, __LINE__)
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#define sx_xlock(sx) _sx_xlock((sx), __FILE__, __LINE__)
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#define sx_sunlock(sx) _sx_sunlock((sx), __FILE__, __LINE__)
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#define sx_xunlock(sx) _sx_xunlock((sx), __FILE__, __LINE__)
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#ifdef INVARIANTS
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/*
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* SX_ASSERT_SLOCKED() can only detect that at least *some* thread owns an
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* slock, but it cannot guarantee that *this* thread owns an slock.
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*/
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#define SX_ASSERT_SLOCKED(sx) do { \
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mtx_lock(&(sx)->sx_lock); \
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_SX_ASSERT_SLOCKED((sx)); \
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mtx_unlock(&(sx)->sx_lock); \
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} while (0)
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#define _SX_ASSERT_SLOCKED(sx) do { \
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KASSERT(((sx)->sx_cnt > 0), ("%s: lacking slock %s\n", \
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__FUNCTION__, (sx)->sx_object.lo_name)); \
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} while (0)
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/*
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* SX_ASSERT_XLOCKED() detects and guarantees that *we* own the xlock.
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*/
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#define SX_ASSERT_XLOCKED(sx) do { \
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mtx_lock(&(sx)->sx_lock); \
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_SX_ASSERT_XLOCKED((sx)); \
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mtx_unlock(&(sx)->sx_lock); \
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} while (0)
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#define _SX_ASSERT_XLOCKED(sx) do { \
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KASSERT(((sx)->sx_xholder == curproc), \
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("%s: thread %p lacking xlock %s\n", __FUNCTION__, \
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curproc, (sx)->sx_object.lo_name)); \
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} while (0)
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#else /* INVARIANTS */
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#define SX_ASSERT_SLOCKED(sx)
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#define SX_ASSERT_XLOCKED(sx)
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#define _SX_ASSERT_SLOCKED(sx)
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#define _SX_ASSERT_XLOCKED(sx)
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#endif /* INVARIANTS */
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#endif /* _KERNEL */
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#endif /* !LOCORE */
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#endif /* _SYS_SX_H_ */
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