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freebsd-skq/sys/i386/include/mutex.h
jhb b996fd3a9d Fix the assmebly mutex macros to handle saving/restoring interrupt state 
properly.  Fix the recursive mutex macros to actually compile.  At the
moment we only use MTX_EXIT anyways.
2000-09-24 23:34:21 +00:00

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/*-
* Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from BSDI $Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp Exp $
* $FreeBSD$
*/
#ifndef _MACHINE_MUTEX_H_
#define _MACHINE_MUTEX_H_
#ifndef LOCORE
#include <sys/ktr.h>
#include <sys/proc.h> /* Needed for curproc. */
#include <sys/queue.h>
#include <machine/atomic.h>
#include <machine/cpufunc.h>
#include <machine/globals.h>
/*
* If kern_mutex.c is being built, compile non-inlined versions of various
* functions so that kernel modules can use them.
*/
#ifndef _KERN_MUTEX_C_
#define _MTX_INLINE static __inline
#else
#define _MTX_INLINE
#endif
/*
* Mutex flags
*
* Types
*/
#define MTX_DEF 0x0 /* Default (spin/sleep) */
#define MTX_SPIN 0x1 /* Spin only lock */
/* Options */
#define MTX_RLIKELY 0x4 /* (opt) Recursion likely */
#define MTX_NORECURSE 0x8 /* No recursion possible */
#define MTX_NOSPIN 0x10 /* Don't spin before sleeping */
#define MTX_NOSWITCH 0x20 /* Do not switch on release */
#define MTX_FIRST 0x40 /* First spin lock holder */
#define MTX_TOPHALF 0x80 /* Interrupts not disabled on spin */
/* options that should be passed on to mtx_enter_hard, mtx_exit_hard */
#define MTX_HARDOPTS (MTX_SPIN | MTX_FIRST | MTX_TOPHALF | MTX_NOSWITCH)
/* Flags/value used in mtx_lock */
#define MTX_RECURSE 0x01 /* (non-spin) lock held recursively */
#define MTX_CONTESTED 0x02 /* (non-spin) lock contested */
#define MTX_FLAGMASK ~(MTX_RECURSE | MTX_CONTESTED)
#define MTX_UNOWNED 0x8 /* Cookie for free mutex */
/*
* Sleep/spin mutex
*/
struct mtx {
volatile u_int mtx_lock; /* lock owner/gate/flags */
volatile u_int mtx_recurse; /* number of recursive holds */
u_int mtx_savefl; /* saved flags (for spin locks) */
char *mtx_description;
TAILQ_HEAD(, proc) mtx_blocked;
LIST_ENTRY(mtx) mtx_contested;
struct mtx *mtx_next; /* all locks in system */
struct mtx *mtx_prev;
#ifdef SMP_DEBUG
/* If you add anything here, adjust the mtxf_t definition below */
struct witness *mtx_witness;
LIST_ENTRY(mtx) mtx_held;
const char *mtx_file;
int mtx_line;
#endif /* SMP_DEBUG */
};
/*
* Filler for structs which need to remain the same size
* whether or not SMP_DEBUG is turned on.
*/
typedef struct mtxf {
#ifdef SMP_DEBUG
char mtxf_data[0];
#else
char mtxf_data[4*sizeof(void *) + sizeof(int)];
#endif
} mtxf_t;
#define mp_fixme(string)
#ifdef _KERNEL
/* Misc */
#define CURTHD ((u_int)CURPROC) /* Current thread ID */
/* Prototypes */
void mtx_init(struct mtx *m, char *description, int flag);
void mtx_enter_hard(struct mtx *, int type, int flags);
void mtx_exit_hard(struct mtx *, int type);
void mtx_destroy(struct mtx *m);
/*
* Wrap the following functions with cpp macros so that filenames and line
* numbers are embedded in the code correctly.
*/
#if (defined(KLD_MODULE) || defined(_KERN_MUTEX_C_))
void _mtx_enter(struct mtx *mtxp, int type, const char *file, int line);
int _mtx_try_enter(struct mtx *mtxp, int type, const char *file, int line);
void _mtx_exit(struct mtx *mtxp, int type, const char *file, int line);
#endif
#define mtx_enter(mtxp, type) \
_mtx_enter((mtxp), (type), __FILE__, __LINE__)
#define mtx_try_enter(mtxp, type) \
_mtx_try_enter((mtxp), (type), __FILE__, __LINE__)
#define mtx_exit(mtxp, type) \
_mtx_exit((mtxp), (type), __FILE__, __LINE__)
/* Global locks */
extern struct mtx sched_lock;
extern struct mtx Giant;
/*
* Used to replace return with an exit Giant and return.
*/
#define EGAR(a) \
do { \
mtx_exit(&Giant, MTX_DEF); \
return (a); \
} while (0)
#define VEGAR \
do { \
mtx_exit(&Giant, MTX_DEF); \
return; \
} while (0)
#define DROP_GIANT() \
do { \
int _giantcnt; \
WITNESS_SAVE_DECL(Giant); \
\
WITNESS_SAVE(&Giant, Giant); \
for (_giantcnt = 0; mtx_owned(&Giant); _giantcnt++) \
mtx_exit(&Giant, MTX_DEF)
#define PICKUP_GIANT() \
mtx_assert(&Giant, MA_NOTOWNED); \
while (_giantcnt--) \
mtx_enter(&Giant, MTX_DEF); \
WITNESS_RESTORE(&Giant, Giant); \
} while (0)
#define PARTIAL_PICKUP_GIANT() \
mtx_assert(&Giant, MA_NOTOWNED); \
while (_giantcnt--) \
mtx_enter(&Giant, MTX_DEF); \
WITNESS_RESTORE(&Giant, Giant)
/*
* Debugging
*/
#ifndef SMP_DEBUG
#define mtx_assert(m, what)
#else /* SMP_DEBUG */
#define MA_OWNED 1
#define MA_NOTOWNED 2
#define mtx_assert(m, what) { \
switch ((what)) { \
case MA_OWNED: \
ASS(mtx_owned((m))); \
break; \
case MA_NOTOWNED: \
ASS(!mtx_owned((m))); \
break; \
default: \
panic("unknown mtx_assert at %s:%d", __FILE__, __LINE__); \
} \
}
#ifdef INVARIANTS
#define ASS(ex) MPASS(ex)
#define MPASS(ex) if (!(ex)) panic("Assertion %s failed at %s:%d", \
#ex, __FILE__, __LINE__)
#define MPASS2(ex, what) if (!(ex)) panic("Assertion %s failed at %s:%d", \
what, __FILE__, __LINE__)
#ifdef MTX_STRS
char STR_IEN[] = "fl & 0x200";
char STR_IDIS[] = "!(fl & 0x200)";
#else /* MTX_STRS */
extern char STR_IEN[];
extern char STR_IDIS[];
#endif /* MTX_STRS */
#define ASS_IEN MPASS2(read_eflags() & 0x200, STR_IEN)
#define ASS_IDIS MPASS2((read_eflags() & 0x200) == 0, STR_IDIS)
#endif /* INVARIANTS */
#endif /* SMP_DEBUG */
#if !defined(SMP_DEBUG) || !defined(INVARIANTS)
#define ASS(ex)
#define MPASS(ex)
#define MPASS2(ex, where)
#define ASS_IEN
#define ASS_IDIS
#endif /* !defined(SMP_DEBUG) || !defined(INVARIANTS) */
#ifdef WITNESS
#ifndef SMP_DEBUG
#error WITNESS requires SMP_DEBUG
#endif /* SMP_DEBUG */
#define WITNESS_ENTER(m, t, f, l) \
if ((m)->mtx_witness != NULL) \
witness_enter((m), (t), (f), (l))
#define WITNESS_EXIT(m, t, f, l) \
if ((m)->mtx_witness != NULL) \
witness_exit((m), (t), (f), (l))
#define WITNESS_SLEEP(check, m) witness_sleep(check, (m), __FILE__, __LINE__)
#define WITNESS_SAVE_DECL(n) \
const char * __CONCAT(n, __wf); \
int __CONCAT(n, __wl)
#define WITNESS_SAVE(m, n) \
do { \
if ((m)->mtx_witness != NULL) \
witness_save(m, &__CONCAT(n, __wf), &__CONCAT(n, __wl)); \
} while (0)
#define WITNESS_RESTORE(m, n) \
do { \
if ((m)->mtx_witness != NULL) \
witness_restore(m, __CONCAT(n, __wf), __CONCAT(n, __wl)); \
} while (0)
void witness_init(struct mtx *, int flag);
void witness_destroy(struct mtx *);
void witness_enter(struct mtx *, int, const char *, int);
void witness_try_enter(struct mtx *, int, const char *, int);
void witness_exit(struct mtx *, int, const char *, int);
void witness_display(void(*)(const char *fmt, ...));
void witness_list(struct proc *);
int witness_sleep(int, struct mtx *, const char *, int);
void witness_save(struct mtx *, const char **, int *);
void witness_restore(struct mtx *, const char *, int);
#else /* WITNESS */
#define WITNESS_ENTER(m, t, f, l)
#define WITNESS_EXIT(m, t, f, l)
#define WITNESS_SLEEP(check, m)
#define WITNESS_SAVE_DECL(n)
#define WITNESS_SAVE(m, n)
#define WITNESS_RESTORE(m, n)
/*
* flag++ is slezoid way of shutting up unused parameter warning
* in mtx_init()
*/
#define witness_init(m, flag) flag++
#define witness_destroy(m)
#define witness_enter(m, t, f, l)
#define witness_try_enter(m, t, f, l)
#define witness_exit(m, t, f, l)
#endif /* WITNESS */
/*
* Assembly macros (for internal use only)
*------------------------------------------------------------------------------
*/
#define _V(x) __STRING(x)
#ifndef I386_CPU
/*
* For 486 and newer processors.
*/
/* Get a sleep lock, deal with recursion inline. */
#define _getlock_sleep(mtxp, tid, type) ({ \
int _res; \
\
__asm __volatile ( \
" movl $" _V(MTX_UNOWNED) ",%%eax;" /* Unowned cookie */ \
" " MPLOCKED "" \
" cmpxchgl %3,%1;" /* Try */ \
" jz 1f;" /* Got it */ \
" andl $" _V(MTX_FLAGMASK) ",%%eax;" /* turn off spec bits */ \
" cmpl %%eax,%3;" /* already have it? */ \
" je 2f;" /* yes, recurse */ \
" pushl %4;" \
" pushl %5;" \
" call mtx_enter_hard;" \
" addl $8,%%esp;" \
" jmp 1f;" \
"2: lock; orl $" _V(MTX_RECURSE) ",%1;" \
" incl %2;" \
"1:" \
"# getlock_sleep" \
: "=&a" (_res), /* 0 (dummy output) */ \
"+m" (mtxp->mtx_lock), /* 1 */ \
"+m" (mtxp->mtx_recurse) /* 2 */ \
: "r" (tid), /* 3 (input) */ \
"gi" (type), /* 4 */ \
"g" (mtxp) /* 5 */ \
: "memory", "ecx", "edx" /* used */ ); \
})
/* Get a spin lock, handle recursion inline (as the less common case) */
#define _getlock_spin_block(mtxp, tid, type) ({ \
int _res; \
\
__asm __volatile ( \
" pushfl;" \
" cli;" \
" movl $" _V(MTX_UNOWNED) ",%%eax;" /* Unowned cookie */ \
" " MPLOCKED "" \
" cmpxchgl %3,%1;" /* Try */ \
" jz 2f;" /* got it */ \
" pushl %4;" \
" pushl %5;" \
" call mtx_enter_hard;" /* mtx_enter_hard(mtxp, type, oflags) */ \
" addl $0xc,%%esp;" \
" jmp 1f;" \
"2: popl %2;" /* save flags */ \
"1:" \
"# getlock_spin_block" \
: "=&a" (_res), /* 0 (dummy output) */ \
"+m" (mtxp->mtx_lock), /* 1 */ \
"=m" (mtxp->mtx_savefl) /* 2 */ \
: "r" (tid), /* 3 (input) */ \
"gi" (type), /* 4 */ \
"g" (mtxp) /* 5 */ \
: "memory", "ecx", "edx" /* used */ ); \
})
/*
* Get a lock without any recursion handling. Calls the hard enter function if
* we can't get it inline.
*/
#define _getlock_norecurse(mtxp, tid, type) ({ \
int _res; \
\
__asm __volatile ( \
" movl $" _V(MTX_UNOWNED) ",%%eax;" /* Unowned cookie */ \
" " MPLOCKED "" \
" cmpxchgl %2,%1;" /* Try */ \
" jz 1f;" /* got it */ \
" pushl %3;" \
" pushl %4;" \
" call mtx_enter_hard;" /* mtx_enter_hard(mtxp, type) */ \
" addl $8,%%esp;" \
"1:" \
"# getlock_norecurse" \
: "=&a" (_res), /* 0 (dummy output) */ \
"+m" (mtxp->mtx_lock) /* 1 */ \
: "r" (tid), /* 2 (input) */ \
"gi" (type), /* 3 */ \
"g" (mtxp) /* 4 */ \
: "memory", "ecx", "edx" /* used */ ); \
})
/*
* Release a sleep lock assuming we haven't recursed on it, recursion is handled
* in the hard function.
*/
#define _exitlock_norecurse(mtxp, tid, type) ({ \
int _tid = (int)(tid); \
\
__asm __volatile ( \
" " MPLOCKED "" \
" cmpxchgl %4,%0;" /* try easy rel */ \
" jz 1f;" /* released! */ \
" pushl %2;" \
" pushl %3;" \
" call mtx_exit_hard;" \
" addl $8,%%esp;" \
"1:" \
"# exitlock_norecurse" \
: "+m" (mtxp->mtx_lock), /* 0 */ \
"+a" (_tid) /* 1 */ \
: "gi" (type), /* 2 (input) */ \
"g" (mtxp), /* 3 */ \
"r" (MTX_UNOWNED) /* 4 */ \
: "memory", "ecx", "edx" /* used */ ); \
})
/*
* Release a sleep lock when its likely we recursed (the code to
* deal with simple recursion is inline).
*/
#define _exitlock(mtxp, tid, type) ({ \
int _tid = (int)(tid); \
\
__asm __volatile ( \
" " MPLOCKED "" \
" cmpxchgl %5,%0;" /* try easy rel */ \
" jz 1f;" /* released! */ \
" testl $" _V(MTX_RECURSE) ",%%eax;" /* recursed? */ \
" jnz 3f;" /* handle recursion */ \
/* Lock not recursed and contested: do the hard way */ \
" pushl %3;" \
" pushl %4;" \
" call mtx_exit_hard;" /* mtx_exit_hard(mtxp,type) */ \
" addl $8,%%esp;" \
" jmp 1f;" \
/* lock recursed, lower recursion level */ \
"3: decl %1;" /* one less level */ \
" jnz 1f;" /* still recursed, done */ \
" lock; andl $~" _V(MTX_RECURSE) ",%0;" /* turn off recurse flag */ \
"1:" \
"# exitlock" \
: "+m" (mtxp->mtx_lock), /* 0 */ \
"+m" (mtxp->mtx_recurse), /* 1 */ \
"+a" (_tid) /* 2 */ \
: "gi" (type), /* 3 (input) */ \
"g" (mtxp), /* 4 */ \
"r" (MTX_UNOWNED) /* 5 */ \
: "memory", "ecx", "edx" /* used */ ); \
})
/*
* Release a spin lock (with possible recursion).
*
* We use cmpxchgl to clear lock (instead of simple store) to flush posting
* buffers and make the change visible to other CPU's.
*/
#define _exitlock_spin(mtxp, inten1, inten2) ({ \
int _res; \
\
__asm __volatile ( \
" movl %1,%%eax;" \
" decl %%eax;" \
" js 1f;" \
" movl %%eax,%1;" \
" jmp 2f;" \
"1: movl %0,%%eax;" \
" movl $ " _V(MTX_UNOWNED) ",%%ecx;" \
" " inten1 ";" \
" " MPLOCKED "" \
" cmpxchgl %%ecx,%0;" \
" " inten2 ";" \
"2:" \
"# exitlock_spin" \
: "+m" (mtxp->mtx_lock), /* 0 */ \
"+m" (mtxp->mtx_recurse), /* 1 */ \
"=&a" (_res) /* 2 */ \
: "g" (mtxp->mtx_savefl) /* 3 (used in 'inten') */ \
: "memory", "ecx" /* used */ ); \
})
#else /* I386_CPU */
/*
* For 386 processors only.
*/
/* Get a sleep lock, deal with recursion inline. */
#define _getlock_sleep(mp, tid, type) do { \
if (atomic_cmpset_int(&(mp)->mtx_lock, MTX_UNOWNED, (tid)) == 0) { \
if (((mp)->mtx_lock & MTX_FLAGMASK) != (tid)) \
mtx_enter_hard(mp, (type) & MTX_HARDOPTS, 0); \
else { \
atomic_set_int(&(mp)->mtx_lock, MTX_RECURSE); \
(mp)->mtx_recurse++; \
} \
} \
} while (0)
/* Get a spin lock, handle recursion inline (as the less common case) */
#define _getlock_spin_block(mp, tid, type) do { \
u_int _mtx_fl = read_eflags(); \
disable_intr(); \
if (atomic_cmpset_int(&(mp)->mtx_lock, MTX_UNOWNED, (tid)) == 0) \
mtx_enter_hard(mp, (type) & MTX_HARDOPTS, _mtx_fl); \
else \
(mp)->mtx_savefl = _mtx_fl; \
} while (0)
/*
* Get a lock without any recursion handling. Calls the hard enter function if
* we can't get it inline.
*/
#define _getlock_norecurse(mp, tid, type) do { \
if (atomic_cmpset_int(&(mp)->mtx_lock, MTX_UNOWNED, (tid)) == 0) \
mtx_enter_hard((mp), (type) & MTX_HARDOPTS, 0); \
} while (0)
/*
* Release a sleep lock assuming we haven't recursed on it, recursion is handled
* in the hard function.
*/
#define _exitlock_norecurse(mp, tid, type) do { \
if (atomic_cmpset_int(&(mp)->mtx_lock, (tid), MTX_UNOWNED) == 0) \
mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \
} while (0)
/*
* Release a sleep lock when its likely we recursed (the code to
* deal with simple recursion is inline).
*/
#define _exitlock(mp, tid, type) do { \
if (atomic_cmpset_int(&(mp)->mtx_lock, (tid), MTX_UNOWNED) == 0) { \
if ((mp)->mtx_lock & MTX_RECURSE) { \
if (--((mp)->mtx_recurse) == 0) \
atomic_clear_int(&(mp)->mtx_lock, \
MTX_RECURSE); \
} else { \
mtx_exit_hard((mp), (type) & MTX_HARDOPTS); \
} \
} \
} while (0)
/* Release a spin lock (with possible recursion). */
#define _exitlock_spin(mp, inten1, inten2) do { \
if ((mp)->mtx_recurse == 0) { \
atomic_cmpset_int(&(mp)->mtx_lock, (mp)->mtx_lock, \
MTX_UNOWNED); \
write_eflags((mp)->mtx_savefl); \
} else { \
(mp)->mtx_recurse--; \
} \
} while (0)
#endif /* I386_CPU */
/*
* Externally visible mutex functions.
*------------------------------------------------------------------------------
*/
/*
* Return non-zero if a mutex is already owned by the current thread.
*/
#define mtx_owned(m) (((m)->mtx_lock & MTX_FLAGMASK) == CURTHD)
/* Common strings */
#ifdef MTX_STRS
#ifdef KTR_EXTEND
/*
* KTR_EXTEND saves file name and line for all entries, so we don't need them
* here. Theoretically we should also change the entries which refer to them
* (from CTR5 to CTR3), but since they're just passed to snprintf as the last
* parameters, it doesn't do any harm to leave them.
*/
char STR_mtx_enter_fmt[] = "GOT %s [%x] r=%d";
char STR_mtx_exit_fmt[] = "REL %s [%x] r=%d";
char STR_mtx_try_enter_fmt[] = "TRY_ENTER %s [%x] result=%d";
#else
char STR_mtx_enter_fmt[] = "GOT %s [%x] at %s:%d r=%d";
char STR_mtx_exit_fmt[] = "REL %s [%x] at %s:%d r=%d";
char STR_mtx_try_enter_fmt[] = "TRY_ENTER %s [%x] at %s:%d result=%d";
#endif
char STR_mtx_bad_type[] = "((type) & (MTX_NORECURSE | MTX_NOSWITCH)) == 0";
char STR_mtx_owned[] = "mtx_owned(mpp)";
char STR_mtx_recurse[] = "mpp->mtx_recurse == 0";
#else /* MTX_STRS */
extern char STR_mtx_enter_fmt[];
extern char STR_mtx_bad_type[];
extern char STR_mtx_exit_fmt[];
extern char STR_mtx_owned[];
extern char STR_mtx_recurse[];
extern char STR_mtx_try_enter_fmt[];
#endif /* MTX_STRS */
#ifndef KLD_MODULE
/*
* Get lock 'm', the macro handles the easy (and most common cases) and leaves
* the slow stuff to the mtx_enter_hard() function.
*
* Note: since type is usually a constant much of this code is optimized out.
*/
_MTX_INLINE void
_mtx_enter(struct mtx *mtxp, int type, const char *file, int line)
{
struct mtx *mpp = mtxp;
/* bits only valid on mtx_exit() */
MPASS2(((type) & (MTX_NORECURSE | MTX_NOSWITCH)) == 0,
STR_mtx_bad_type);
if ((type) & MTX_SPIN) {
/*
* Easy cases of spin locks:
*
* 1) We already own the lock and will simply recurse on it (if
* RLIKELY)
*
* 2) The lock is free, we just get it
*/
if ((type) & MTX_RLIKELY) {
/*
* Check for recursion, if we already have this
* lock we just bump the recursion count.
*/
if (mpp->mtx_lock == CURTHD) {
mpp->mtx_recurse++;
goto done;
}
}
if (((type) & MTX_TOPHALF) == 0) {
/*
* If an interrupt thread uses this we must block
* interrupts here.
*/
if ((type) & MTX_FIRST) {
ASS_IEN;
disable_intr();
_getlock_norecurse(mpp, CURTHD,
(type) & MTX_HARDOPTS);
} else {
_getlock_spin_block(mpp, CURTHD,
(type) & MTX_HARDOPTS);
}
} else
_getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS);
} else {
/* Sleep locks */
if ((type) & MTX_RLIKELY)
_getlock_sleep(mpp, CURTHD, (type) & MTX_HARDOPTS);
else
_getlock_norecurse(mpp, CURTHD, (type) & MTX_HARDOPTS);
}
done:
WITNESS_ENTER(mpp, type, file, line);
CTR5(KTR_LOCK, STR_mtx_enter_fmt,
mpp->mtx_description, mpp, file, line,
mpp->mtx_recurse);
}
/*
* Attempt to get MTX_DEF lock, return non-zero if lock acquired.
*
* XXX DOES NOT HANDLE RECURSION
*/
_MTX_INLINE int
_mtx_try_enter(struct mtx *mtxp, int type, const char *file, int line)
{
struct mtx *const mpp = mtxp;
int rval;
rval = atomic_cmpset_int(&mpp->mtx_lock, MTX_UNOWNED, CURTHD);
#ifdef SMP_DEBUG
if (rval && mpp->mtx_witness != NULL) {
ASS(mpp->mtx_recurse == 0);
witness_try_enter(mpp, type, file, line);
}
#endif
CTR5(KTR_LOCK, STR_mtx_try_enter_fmt,
mpp->mtx_description, mpp, file, line, rval);
return rval;
}
#define mtx_legal2block() (read_eflags() & 0x200)
/*
* Release lock m.
*/
_MTX_INLINE void
_mtx_exit(struct mtx *mtxp, int type, const char *file, int line)
{
struct mtx *const mpp = mtxp;
MPASS2(mtx_owned(mpp), STR_mtx_owned);
WITNESS_EXIT(mpp, type, file, line);
CTR5(KTR_LOCK, STR_mtx_exit_fmt,
mpp->mtx_description, mpp, file, line,
mpp->mtx_recurse);
if ((type) & MTX_SPIN) {
if ((type) & MTX_NORECURSE) {
MPASS2(mpp->mtx_recurse == 0, STR_mtx_recurse);
atomic_cmpset_int(&mpp->mtx_lock, mpp->mtx_lock,
MTX_UNOWNED);
if (((type) & MTX_TOPHALF) == 0) {
if ((type) & MTX_FIRST) {
ASS_IDIS;
enable_intr();
} else
write_eflags(mpp->mtx_savefl);
}
} else {
if ((type) & MTX_TOPHALF)
_exitlock_spin(mpp,,);
else {
if ((type) & MTX_FIRST) {
ASS_IDIS;
_exitlock_spin(mpp,, "sti");
} else {
_exitlock_spin(mpp,
"pushl %3", "popfl");
}
}
}
} else {
/* Handle sleep locks */
if ((type) & MTX_RLIKELY)
_exitlock(mpp, CURTHD, (type) & MTX_HARDOPTS);
else {
_exitlock_norecurse(mpp, CURTHD,
(type) & MTX_HARDOPTS);
}
}
}
#endif /* KLD_MODULE */
#endif /* _KERNEL */
#else /* !LOCORE */
/*
* Simple assembly macros to get and release non-recursive spin locks
*/
#if defined(I386_CPU)
#define MTX_EXIT(lck, reg) \
pushl lck+MTX_SAVEFL; \
movl $ MTX_UNOWNED,lck+MTX_LOCK; \
popf
#else /* I386_CPU */
#define MTX_ENTER(reg, lck) \
pushf \
cli \
9: movl $ MTX_UNOWNED,%eax; \
MPLOCKED \
cmpxchgl reg,lck+MTX_LOCK; \
jnz 9b; \
popl lck+MTX_SAVEFL;
/* Must use locked bus op (cmpxchg) when setting to unowned (barrier) */
#define MTX_EXIT(lck,reg) \
pushl lck+MTX_SAVEFL; \
movl lck+MTX_LOCK,%eax; \
movl $ MTX_UNOWNED,reg; \
MPLOCKED \
cmpxchgl reg,lck+MTX_LOCK; \
popf
#define MTX_ENTER_WITH_RECURSION(reg, lck) \
pushf \
cli \
movl lck+MTX_LOCK,%eax; \
cmpl _curproc,%eax; \
jne 9f; \
incw lck+MTX_RECURS; \
jmp 8f; \
9: movl $ MTX_UNOWNED,%eax; \
MPLOCKED \
cmpxchgl reg,lck+MTX_LOCK; \
jnz 9b; \
popl lck+MTX_SAVEFL; \
jmp 10f; \
8: add $4,%esp; \
10:
#define MTX_EXIT_WITH_RECURSION(lck,reg) \
movl lck+MTX_RECURSE,%eax; \
decl %eax; \
js 9f; \
movl %eax,lck+MTX_RECURSE; \
jmp 8f; \
pushl lck+MTX_SAVEFL; \
9: movl lck+MTX_LOCK,%eax; \
movl $ MTX_UNOWNED,reg; \
MPLOCKED \
cmpxchgl reg,lck+MTX_LOCK; \
popf \
8:
#endif /* I386_CPU */
#endif /* !LOCORE */
#endif /* __MACHINE_MUTEX_H */
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