1 /*        $NetBSD: lwp.h,v 1.231 2023/11/02 10:31:55 martin Exp $     */
2 
3 /*
4  * Copyright (c) 2001, 2006, 2007, 2008, 2009, 2010, 2019, 2020, 2023
5  *    The NetBSD Foundation, Inc.
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to The NetBSD Foundation
9  * by Nathan J. Williams and Andrew Doran.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #ifndef _SYS_LWP_H_
34 #define _SYS_LWP_H_
35 
36 #if defined(_KERNEL) || defined(_KMEMUSER)
37 
38 #include <sys/param.h>
39 
40 #include <sys/callout.h>
41 #include <sys/condvar.h>
42 #include <sys/kcpuset.h>
43 #include <sys/mutex.h>
44 #include <sys/queue.h>
45 #include <sys/resource.h>
46 #include <sys/sched.h>
47 #include <sys/signalvar.h>
48 #include <sys/specificdata.h>
49 #include <sys/time.h>
50 #include <sys/wchan.h>
51 
52 #if defined(_KERNEL)
53 struct lwp;
54 /* forward declare this for <machine/cpu.h> so it can get l_cpu. */
55 static __inline struct cpu_info *lwp_getcpu(struct lwp *);
56 #include <machine/cpu.h>                /* curcpu() and cpu_info */
57 #include <sys/atomic.h>
58 #ifdef _KERNEL_OPT
59 #include "opt_kcov.h"
60 #include "opt_kmsan.h"
61 #include "opt_maxlwp.h"
62 #endif
63 #endif
64 
65 #include <machine/proc.h>               /* Machine-dependent proc substruct. */
66 
67 /*
68  * Lightweight process.  Field markings and the corresponding locks:
69  *
70  * a:     proc_lock
71  * c:     condition variable interlock, passed to cv_wait()
72  * l:     *l_mutex
73  * p:     l_proc->p_lock
74  * s:     spc_mutex, which may or may not be referenced by l_mutex
75  * S:     l_selcluster->sc_lock
76  * (:     unlocked, stable
77  * !:     unlocked, may only be reliably accessed by the LWP itself
78  *
79  * Fields are clustered together by usage (to increase the likelihood
80  * of cache hits) and by size (to reduce dead space in the structure).
81  */
82 
83 #include <sys/pcu.h>
84 
85 struct lockdebug;
86 struct sysent;
87 
88 struct lwp {
89           /* Must not be zeroed on free. */
90           struct cpu_info *volatile l_cpu;/* s: CPU we're on if LSONPROC */
91           kmutex_t * volatile l_mutex;  /* l: ptr to mutex on sched state */
92           struct turnstile *l_ts;                 /* l: current turnstile */
93           int                 l_stat;             /* l: overall LWP status */
94           int                 l__reserved;        /*  : padding - reuse as needed */
95 
96           /* Scheduling and overall state. */
97 #define   l_startzero l_runq
98           TAILQ_ENTRY(lwp) l_runq;      /* s: run queue */
99           union {
100                     void *    info;               /* s: scheduler-specific structure */
101                     u_int     timeslice;          /* l: time-quantum for SCHED_M2 */
102           } l_sched;
103           void                *l_addr;  /* l: PCB address; use lwp_getpcb() */
104           struct mdlwp        l_md;               /* l: machine-dependent fields. */
105           struct bintime      l_rtime;  /* l: real time */
106           struct bintime      l_stime;  /* l: start time (while ONPROC) */
107           int                 l_flag;             /* l: misc flag values */
108           u_int               l_swtime; /* l: time swapped in or out */
109           u_int               l_rticks; /* l: Saved start time of run */
110           u_int               l_rticksum;         /* l: Sum of ticks spent running */
111           u_int               l_slpticks;         /* l: Saved start time of sleep */
112           u_int               l_slpticksum;       /* l: Sum of ticks spent sleeping */
113           int                 l_class;  /* l: scheduling class */
114           pri_t               l_boostpri;         /* l: boosted priority after blocking */
115           pri_t               l_priority;         /* l: scheduler priority */
116           pri_t               l_inheritedprio;/* l: inherited priority */
117           pri_t               l_protectprio;      /* l: for PTHREAD_PRIO_PROTECT */
118           pri_t               l_auxprio;          /* l: max(inherit,protect) priority */
119           int                 l_protectdepth;     /* l: for PTHREAD_PRIO_PROTECT */
120           u_int               l_cpticks;          /* (: Ticks of CPU time */
121           psetid_t  l_psid;             /* l: assigned processor-set ID */
122           fixpt_t             l_pctcpu; /* p: %cpu during l_swtime */
123           fixpt_t             l_estcpu; /* l: cpu time for SCHED_4BSD */
124           SLIST_HEAD(, turnstile) l_pi_lenders; /* l: ts lending us priority */
125           struct cpu_info *l_target_cpu;          /* l: target CPU to migrate */
126           struct lwpctl       *l_lwpctl;          /* p: lwpctl block kernel address */
127           struct lcpage       *l_lcpage;          /* p: lwpctl containing page */
128           kcpuset_t *l_affinity;        /* l: CPU set for affinity */
129 
130           /* Synchronisation. */
131           const struct syncobj *l_syncobj;/* l: sync object operations set */
132           LIST_ENTRY(lwp) l_sleepchain; /* l: sleep queue */
133           wchan_t             l_wchan;  /* l: sleep address */
134           const char          *l_wmesg; /* l: reason for sleep */
135           struct sleepq       *l_sleepq;          /* l: current sleep queue */
136           callout_t l_timeout_ch;       /* !: callout for tsleep */
137           kcondvar_t          l_waitcv; /* a: vfork() wait */
138           u_int               l_slptime;          /* l: time since last blocked */
139           bool                l_vforkwaiting;     /* a: vfork() waiting */
140 
141           /* User-space synchronization. */
142           uintptr_t l_robust_head;      /* !: list of robust futexes */
143           uint32_t  l___rsvd1;          /* reserved for future use */
144 
145 #if PCU_UNIT_COUNT > 0
146           struct cpu_info     * volatile l_pcu_cpu[PCU_UNIT_COUNT];
147           uint32_t  l_pcu_valid;
148 #endif
149 
150           /* Process level and global state, misc. */
151           lwpid_t             l_lid;              /* (: LWP identifier; local to proc */
152           LIST_ENTRY(lwp)     l_list;             /* a: entry on list of all LWPs */
153           void                *l_ctxlink;         /* p: uc_link {get,set}context */
154           struct proc         *l_proc;  /* p: parent process */
155           LIST_ENTRY(lwp)     l_sibling;          /* p: entry on proc's list of LWPs */
156           char                *l_name;  /* (: name, optional */
157           lwpid_t             l_waiter; /* p: first LWP waiting on us */
158           lwpid_t   l_waitingfor;       /* p: specific LWP we are waiting on */
159           int                 l_prflag; /* p: process level flags */
160           u_int               l_refcnt; /* p: reference count on this LWP */
161 
162           /* State of select() or poll(). */
163           int                 l_selflag;          /* S: polling state flags */
164           int                 l_selret; /* S: return value of select/poll */
165           SLIST_HEAD(,selinfo) l_selwait;         /* S: descriptors waited on */
166           uintptr_t l_selrec; /* !: argument for selrecord() */
167           struct selcluster *l_selcluster;/* !: associated cluster data */
168           void *              l_selbits;          /* (: select() bit-field */
169           size_t              l_selni;  /* (: size of a single bit-field */
170 
171           /* Signals. */
172           int                 l_sigrestore;       /* p: need to restore old sig mask */
173           sigset_t  l_sigwaitset;       /* p: signals being waited for */
174           kcondvar_t          l_sigcv;  /* p: for sigsuspend() */
175           struct ksiginfo     *l_sigwaited;       /* p: delivered signals from set */
176           sigpend_t *l_sigpendset;      /* p: XXX issignal()/postsig() baton */
177           LIST_ENTRY(lwp)     l_sigwaiter;        /* p: chain on list of waiting LWPs */
178           stack_t             l_sigstk; /* p: sp & on stack state variable */
179           sigset_t  l_sigmask;          /* p: signal mask */
180           sigpend_t l_sigpend;          /* p: signals to this LWP */
181           sigset_t  l_sigoldmask;       /* p: mask for sigpause */
182 
183           /* Private data. */
184           specificdata_reference
185                     l_specdataref;                /* !: subsystem lwp-specific data */
186           struct timespec l_ktrcsw;     /* !: for ktrace CSW trace XXX */
187           void                *l_private;         /* !: svr4-style lwp-private data */
188           struct lwp          *l_switchto;        /* !: mi_switch: switch to this LWP */
189           struct kauth_cred *l_cred;    /* !: cached credentials */
190           struct filedesc     *l_fd;              /* !: cached copy of proc::p_fd */
191           void                *l_emuldata;        /* !: kernel lwp-private data */
192           struct fstrans_lwp_info *l_fstrans; /* (: fstrans private data */
193           u_short             l_shlocks;          /* !: lockdebug: shared locks held */
194           u_short             l_exlocks;          /* !: lockdebug: excl. locks held */
195           u_short             l_psrefs; /* !: count of psref held */
196           u_short             l_blcnt;  /* !: count of kernel_lock held */
197           volatile int        l_nopreempt;        /* !: don't preempt me! */
198           volatile u_int      l_dopreempt;        /* s: kernel preemption pending */
199           int                 l_pflag;  /* !: LWP private flags */
200           int                 l_dupfd;  /* !: side return from cloning devs XXX */
201           const struct sysent * volatile l_sysent;/* !: currently active syscall */
202           struct rusage       l_ru;               /* !: accounting information */
203           uint64_t  l_pfailtime;        /* !: for kernel preemption */
204           uintptr_t l_pfailaddr;        /* !: for kernel preemption */
205           uintptr_t l_pfaillock;        /* !: for kernel preemption */
206           _TAILQ_HEAD(,struct lockdebug,volatile) l_ld_locks;/* !: locks held by LWP */
207           volatile void       *l_ld_wanted;       /* !: lock currently wanted by LWP */
208           uintptr_t l_rwcallsite;       /* !: rwlock actual callsite */
209           int                 l_tcgen;  /* !: for timecounter removal */
210 
211           /* These are only used by 'options SYSCALL_TIMES'. */
212           uint32_t  l_syscall_time;     /* !: time epoch for current syscall */
213           uint64_t  *l_syscall_counter; /* !: counter for current process */
214 
215           struct kdtrace_thread *l_dtrace; /* (: DTrace-specific data. */
216 
217 #ifdef KMSAN
218           void                *l_kmsan; /* !: KMSAN private data. */
219 #endif
220 #ifdef KCOV
221           void                *l_kcov; /* !: KCOV private data. */
222 #endif
223 };
224 
225 /*
226  * UAREA_PCB_OFFSET: an offset of PCB structure in the uarea.  MD code may
227  * define it in <machine/proc.h>, to indicate a different uarea layout.
228  */
229 #ifndef UAREA_PCB_OFFSET
230 #define   UAREA_PCB_OFFSET    0
231 #endif
232 
233 LIST_HEAD(lwplist, lwp);                /* A list of LWPs. */
234 
235 #ifdef _KERNEL
236 extern struct lwplist         alllwp;             /* List of all LWPs. */
237 extern lwp_t                  lwp0;               /* LWP for proc0. */
238 extern int                    maxlwp __read_mostly;         /* max number of lwps */
239 #ifndef MAXLWP
240 #define   MAXLWP              4096                /* default max */
241 #endif
242 #ifndef MAXMAXLWP
243 #define MAXMAXLWP   65535               /* absolute max */
244 #endif
245 #endif
246 
247 #endif /* _KERNEL || _KMEMUSER */
248 
249 /*
250  * These flags are kept in l_flag, and they are modified only with the LWP
251  * locked.
252  */
253 #define   LW_IDLE             0x00000001 /* Idle lwp. */
254 #define   LW_LWPCTL 0x00000002 /* Adjust lwpctl in userret */
255 #define   LW_STIMO  0x00000040 /* Sleep timed out */
256 #define   LW_SINTR  0x00000080 /* Sleep is interruptible. */
257 #define   LW_CATCHINTR        0x00000100 /* LW_SINTR intent; see sleepq_block(). */
258 #define   LW_SYSTEM 0x00000200 /* Kernel thread */
259 #define   LW_SYSTEM_FPU       0x00000400 /* Kernel thread with vector/FP enabled */
260 #define   LW_DBGSUSPEND       0x00010000 /* Suspend by debugger */
261 #define   LW_WSUSPEND         0x00020000 /* Suspend before return to user */
262 #define   LW_BATCH  0x00040000 /* LWP tends to hog CPU */
263 #define   LW_WCORE  0x00080000 /* Stop for core dump on return to user */
264 #define   LW_WEXIT  0x00100000 /* Exit before return to user */
265 #define   LW_PENDSIG          0x01000000 /* Pending signal for us */
266 #define   LW_CANCELLED        0x02000000 /* tsleep should not sleep */
267 #define   LW_CACHECRED        0x04000000 /* Cache new process credential */
268 #define   LW_WREBOOT          0x08000000 /* System is rebooting, please suspend */
269 #define   LW_UNPARKED         0x10000000 /* Unpark op pending */
270 #define   LW_RUMP_CLEAR       0x40000000 /* Clear curlwp in RUMP scheduler */
271 #define   LW_RUMP_QEXIT       0x80000000 /* LWP should exit ASAP */
272 
273 /*
274  * The second set of flags is kept in l_pflag, and they are modified only by
275  * the LWP itself, or modified when it's known the LWP cannot be running.
276  * LP_RUNNING is typically updated with the LWP locked, but not always in
277  * the case of soft interrupt handlers.
278  */
279 #define   LP_KTRACTIVE        0x00000001 /* Executing ktrace operation */
280 #define   LP_KTRCSW 0x00000002 /* ktrace context switch marker */
281 #define   LP_KTRCSWUSER       0x00000004 /* ktrace context switch marker */
282           /*                  0x00000008    was LP_PIDLID */
283 #define   LP_OWEUPC 0x00000010 /* Owe user profiling tick */
284 #define   LP_MPSAFE 0x00000020 /* Starts life without kernel_lock */
285 #define   LP_INTR             0x00000040 /* Soft interrupt handler */
286 #define   LP_SYSCTLWRITE      0x00000080 /* sysctl write lock held */
287 #define   LP_MUSTJOIN         0x00000100 /* Must join kthread on exit */
288 #define   LP_SINGLESTEP       0x00000400 /* Single step thread in ptrace(2) */
289 #define   LP_TIMEINTR         0x00010000 /* Time this soft interrupt */
290 #define   LP_PREEMPTING       0x00020000 /* mi_switch called involuntarily */
291 #define   LP_RUNNING          0x20000000 /* Active on a CPU */
292 #define   LP_TELEPORT         0x40000000 /* Teleport to new CPU on preempt() */
293 #define   LP_BOUND  0x80000000 /* Bound to a CPU */
294 
295 /*
296  * The third set of flags is kept in l_prflag and they are modified only
297  * with p_lock held.
298  */
299 #define   LPR_DETACHED        0x00800000 /* Won't be waited for. */
300 #define   LPR_DRAINING        0x80000000 /* Draining references before exiting */
301 
302 /*
303  * Mask indicating that there is "exceptional" work to be done on return to
304  * user.
305  */
306 #define   LW_USERRET          (LW_WEXIT | LW_PENDSIG | LW_WREBOOT | LW_WSUSPEND \
307     | LW_WCORE | LW_LWPCTL | LW_CACHECRED)
308 
309 /*
310  * Status values.
311  *
312  * A note about LSRUN and LSONPROC: LSRUN indicates that a process is
313  * runnable but *not* yet running, i.e. is on a run queue.  LSONPROC
314  * indicates that the process is actually executing on a CPU, i.e.
315  * it is no longer on a run queue.
316  *
317  * These values are set in stone and must not be reused with future changes.
318  */
319 #define   LSIDL               1         /* Process being created by fork. */
320 #define   LSRUN               2         /* Currently runnable. */
321 #define   LSSLEEP             3         /* Sleeping on an address. */
322 #define   LSSTOP              4         /* Process debugging or suspension. */
323 #define   LSZOMB              5         /* Awaiting collection by parent. */
324 /* define LSDEAD    6         Process is almost a zombie. (removed in 5.0) */
325 #define   LSONPROC  7         /* Process is currently on a CPU. */
326 #define   LSSUSPENDED         8         /* Not running, not signalable. */
327 
328 #if defined(_KERNEL) || defined(_KMEMUSER)
329 static __inline void *
lwp_getpcb(struct lwp * l)330 lwp_getpcb(struct lwp *l)
331 {
332 
333           return l->l_addr;
334 }
335 #endif /* _KERNEL || _KMEMUSER */
336 
337 #ifdef _KERNEL
338 void      lwpinit(void);
339 void      lwp0_init(void);
340 
341 void      lwp_startup(lwp_t *, lwp_t *);
342 void      startlwp(void *);
343 
344 void      lwp_lock(lwp_t *);
345 void      lwp_unlock(lwp_t *);
346 pri_t     lwp_eprio(lwp_t *);
347 int       lwp_locked(lwp_t *, kmutex_t *);
348 kmutex_t *lwp_setlock(lwp_t *, kmutex_t *);
349 void      lwp_unlock_to(lwp_t *, kmutex_t *);
350 int       lwp_trylock(lwp_t *);
351 void      lwp_changepri(lwp_t *, pri_t);
352 void      lwp_lendpri(lwp_t *, pri_t);
353 void      lwp_addref(lwp_t *);
354 void      lwp_delref(lwp_t *);
355 void      lwp_delref2(lwp_t *);
356 bool      lwp_drainrefs(lwp_t *);
357 bool      lwp_alive(lwp_t *);
358 lwp_t     *lwp_find_first(proc_t *);
359 
360 int       lwp_wait(lwp_t *, lwpid_t, lwpid_t *, bool);
361 void      lwp_continue(lwp_t *);
362 void      lwp_unsleep(lwp_t *, bool);
363 void      lwp_unstop(lwp_t *);
364 void      lwp_exit(lwp_t *);
365 int       lwp_suspend(lwp_t *, lwp_t *);
366 int       lwp_create1(lwp_t *, const void *, size_t, u_long, lwpid_t *);
367 void      lwp_start(lwp_t *, int);
368 void      lwp_migrate(lwp_t *, struct cpu_info *);
369 lwp_t *   lwp_find2(pid_t, lwpid_t);
370 lwp_t *   lwp_find(proc_t *, int);
371 void      lwp_userret(lwp_t *);
372 void      lwp_need_userret(lwp_t *);
373 void      lwp_free(lwp_t *, bool, bool);
374 long      lwp_pctr(void);
375 int       lwp_setprivate(lwp_t *, void *);
376 int       do_lwp_create(lwp_t *, void *, u_long, lwp_t **, const sigset_t *,
377     const stack_t *);
378 
379 void      lwp_thread_cleanup(lwp_t *);
380 
381 void      lwpinit_specificdata(void);
382 int       lwp_specific_key_create(specificdata_key_t *, specificdata_dtor_t);
383 void      lwp_specific_key_delete(specificdata_key_t);
384 void      lwp_initspecific(lwp_t *);
385 void      lwp_finispecific(lwp_t *);
386 void      *lwp_getspecific(specificdata_key_t);
387 #if defined(_LWP_API_PRIVATE)
388 void      *_lwp_getspecific_by_lwp(lwp_t *, specificdata_key_t);
389 #endif
390 void      lwp_setspecific(specificdata_key_t, void *);
391 void      lwp_setspecific_by_lwp(lwp_t *, specificdata_key_t, void *);
392 
393 /* Syscalls. */
394 int       lwp_park(clockid_t, int, struct timespec *);
395 int       lwp_unpark(const lwpid_t *, const u_int);
396 
397 /* DDB. */
398 void      lwp_whatis(uintptr_t, void (*)(const char *, ...) __printflike(1, 2));
399 
400 int lwp_create(lwp_t *, struct proc *, vaddr_t, int, void *, size_t,
401     void (*)(void *), void *, lwp_t **, int, const sigset_t *, const stack_t *);
402 
403 /*
404  * XXX _MODULE
405  * We should provide real stubs for the below that modules can use.
406  */
407 
408 static __inline void
spc_lock(struct cpu_info * ci)409 spc_lock(struct cpu_info *ci)
410 {
411           mutex_spin_enter(ci->ci_schedstate.spc_mutex);
412 }
413 
414 static __inline void
spc_unlock(struct cpu_info * ci)415 spc_unlock(struct cpu_info *ci)
416 {
417           mutex_spin_exit(ci->ci_schedstate.spc_mutex);
418 }
419 
420 static __inline void
spc_dlock(struct cpu_info * ci1,struct cpu_info * ci2)421 spc_dlock(struct cpu_info *ci1, struct cpu_info *ci2)
422 {
423           struct schedstate_percpu *spc1 = &ci1->ci_schedstate;
424           struct schedstate_percpu *spc2 = &ci2->ci_schedstate;
425 
426           KASSERT(ci1 != ci2);
427           if (ci1 < ci2) {
428                     mutex_spin_enter(spc1->spc_mutex);
429                     mutex_spin_enter(spc2->spc_mutex);
430           } else {
431                     mutex_spin_enter(spc2->spc_mutex);
432                     mutex_spin_enter(spc1->spc_mutex);
433           }
434 }
435 
436 /*
437  * Allow machine-dependent code to override curlwp in <machine/cpu.h> for
438  * its own convenience.  Otherwise, we declare it as appropriate.
439  */
440 #if !defined(curlwp)
441 #if defined(MULTIPROCESSOR)
442 #define   curlwp              curcpu()->ci_curlwp /* Current running LWP */
443 #else
444 extern struct lwp   *curlwp;            /* Current running LWP */
445 #endif /* MULTIPROCESSOR */
446 #endif /* ! curlwp */
447 #define   curproc             (curlwp->l_proc)
448 
449 /*
450  * This provides a way for <machine/cpu.h> to get l_cpu for curlwp before
451  * struct lwp is defined.
452  */
453 static __inline struct cpu_info *
lwp_getcpu(struct lwp * l)454 lwp_getcpu(struct lwp *l)
455 {
456           return l->l_cpu;
457 }
458 
459 static __inline bool
CURCPU_IDLE_P(void)460 CURCPU_IDLE_P(void)
461 {
462           struct cpu_info *ci = curcpu();
463           return ci->ci_onproc == ci->ci_data.cpu_idlelwp;
464 }
465 
466 /*
467  * Disable and re-enable preemption.  Only for low-level kernel
468  * use.  Device drivers and anything that could potentially be
469  * compiled as a module should use kpreempt_disable() and
470  * kpreempt_enable().
471  */
472 static __inline void
KPREEMPT_DISABLE(lwp_t * l)473 KPREEMPT_DISABLE(lwp_t *l)
474 {
475           struct lwp *l1 __diagused;
476 
477           KASSERTMSG(l == (l1 = curlwp), "l=%p curlwp=%p", l, l1);
478           l->l_nopreempt++;
479           __insn_barrier();
480 }
481 
482 static __inline void
KPREEMPT_ENABLE(lwp_t * l)483 KPREEMPT_ENABLE(lwp_t *l)
484 {
485           struct lwp *l1 __diagused;
486 
487           KASSERTMSG(l == (l1 = curlwp), "l=%p curlwp=%p", l, l1);
488           KASSERT(l->l_nopreempt > 0);
489           __insn_barrier();
490           l->l_nopreempt--;
491           __insn_barrier();
492           if (__predict_false(l->l_dopreempt))
493                     kpreempt(0);
494 }
495 
496 /* For lwp::l_dopreempt */
497 #define   DOPREEMPT_ACTIVE    0x01
498 #define   DOPREEMPT_COUNTED   0x02
499 
500 /*
501  * Prevent curlwp from migrating between CPUs between curlwp_bind and
502  * curlwp_bindx. One use case is psref(9) that has a contract that
503  * forbids migrations.
504  */
505 static __inline int
curlwp_bind(void)506 curlwp_bind(void)
507 {
508           int bound;
509 
510           bound = curlwp->l_pflag & LP_BOUND;
511           curlwp->l_pflag |= LP_BOUND;
512           __insn_barrier();
513 
514           return bound;
515 }
516 
517 static __inline void
curlwp_bindx(int bound)518 curlwp_bindx(int bound)
519 {
520 
521           KASSERT(curlwp->l_pflag & LP_BOUND);
522           __insn_barrier();
523           curlwp->l_pflag ^= bound ^ LP_BOUND;
524 }
525 
526 #endif /* _KERNEL */
527 
528 /* Flags for _lwp_create(), as per Solaris. */
529 #define   LWP_DETACHED        0x00000040
530 #define   LWP_SUSPENDED       0x00000080
531 
532 /* Kernel-internal flags for LWP creation. */
533           /*                  0x40000000          was LWP_PIDLID */
534 #define   LWP_VFORK 0x80000000
535 
536 #endif    /* !_SYS_LWP_H_ */
537