nsz Git - musl/blob - src/thread/pthread_create.c

   1 #include "pthread_impl.h"
   2 #include "stdio_impl.h"
   3 #include <sys/mman.h>
   4
   5 static void dummy_0()
   6 {
   7 }
   8 weak_alias(dummy_0, __acquire_ptc);
   9 weak_alias(dummy_0, __release_ptc);
  10 weak_alias(dummy_0, __pthread_tsd_run_dtors);
  11
  12 _Noreturn void pthread_exit(void *result)
  13 {
  14         pthread_t self = pthread_self();
  15         int n;
  16
  17         self->result = result;
  18
  19         while (self->cancelbuf) {
  20                 void (*f)(void *) = self->cancelbuf->__f;
  21                 void *x = self->cancelbuf->__x;
  22                 self->cancelbuf = self->cancelbuf->__next;
  23                 f(x);
  24         }
  25
  26         __pthread_tsd_run_dtors();
  27
  28         __lock(self->exitlock);
  29
  30         /* Mark this thread dead before decrementing count */
  31         __lock(self->killlock);
  32         self->dead = 1;
  33         __unlock(self->killlock);
  34
  35         do n = libc.threads_minus_1;
  36         while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
  37         if (!n) exit(0);
  38
  39         if (self->detached && self->map_base) {
  40                 if (self->detached == 2)
  41                         __syscall(SYS_set_tid_address, 0);
  42                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
  43                         SIGALL_SET, 0, _NSIG/8);
  44                 __unmapself(self->map_base, self->map_size);
  45         }
  46
  47         for (;;) __syscall(SYS_exit, 0);
  48 }
  49
  50 void __do_cleanup_push(struct __ptcb *cb)
  51 {
  52         struct pthread *self = pthread_self();
  53         cb->__next = self->cancelbuf;
  54         self->cancelbuf = cb;
  55 }
  56
  57 void __do_cleanup_pop(struct __ptcb *cb)
  58 {
  59         __pthread_self()->cancelbuf = cb->__next;
  60 }
  61
  62 static int start(void *p)
  63 {
  64         pthread_t self = p;
  65         if (self->startlock[0]) {
  66                 __wait(self->startlock, 0, 1, 1);
  67                 if (self->startlock[0]) {
  68                         self->detached = 2;
  69                         pthread_exit(0);
  70                 }
  71                 __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
  72                         self->sigmask, 0, _NSIG/8);
  73         }
  74         if (self->unblock_cancel)
  75                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  76                         SIGPT_SET, 0, _NSIG/8);
  77         pthread_exit(self->start(self->start_arg));
  78         return 0;
  79 }
  80
  81 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
  82
  83 /* pthread_key_create.c overrides this */
  84 static const size_t dummy = 0;
  85 weak_alias(dummy, __pthread_tsd_size);
  86
  87 static FILE *const dummy_file = 0;
  88 weak_alias(dummy_file, __stdin_used);
  89 weak_alias(dummy_file, __stdout_used);
  90 weak_alias(dummy_file, __stderr_used);
  91
  92 static void init_file_lock(FILE *f)
  93 {
  94         if (f && f->lock<0) f->lock = 0;
  95 }
  96
  97 void *__copy_tls(unsigned char *);
  98
  99 int pthread_create(pthread_t *restrict res, const pthread_attr_t *restrict attrp, void *(*entry)(void *), void *restrict arg)
 100 {
 101         int ret;
 102         size_t size, guard;
 103         struct pthread *self = pthread_self(), *new;
 104         unsigned char *map = 0, *stack = 0, *tsd = 0, *stack_limit;
 105         unsigned flags = 0x7d8f00;
 106         int do_sched = 0;
 107         pthread_attr_t attr = {0};
 108
 109         if (!self) return ENOSYS;
 110         if (!libc.threaded) {
 111                 for (FILE *f=libc.ofl_head; f; f=f->next)
 112                         init_file_lock(f);
 113                 init_file_lock(__stdin_used);
 114                 init_file_lock(__stdout_used);
 115                 init_file_lock(__stderr_used);
 116                 libc.threaded = 1;
 117         }
 118         if (attrp) attr = *attrp;
 119
 120         __acquire_ptc();
 121
 122         if (attr._a_stackaddr) {
 123                 size_t need = libc.tls_size + __pthread_tsd_size;
 124                 size = attr._a_stacksize + DEFAULT_STACK_SIZE;
 125                 stack = (void *)(attr._a_stackaddr & -16);
 126                 stack_limit = (void *)(attr._a_stackaddr - size);
 127                 /* Use application-provided stack for TLS only when
 128                  * it does not take more than ~12% or 2k of the
 129                  * application's stack space. */
 130                 if (need < size/8 && need < 2048) {
 131                         tsd = stack - __pthread_tsd_size;
 132                         stack = tsd - libc.tls_size;
 133                 } else {
 134                         size = ROUND(need);
 135                         guard = 0;
 136                 }
 137         } else {
 138                 guard = ROUND(DEFAULT_GUARD_SIZE + attr._a_guardsize);
 139                 size = guard + ROUND(DEFAULT_STACK_SIZE + attr._a_stacksize
 140                         + libc.tls_size +  __pthread_tsd_size);
 141         }
 142
 143         if (!tsd) {
 144                 if (guard) {
 145                         map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
 146                         if (map == MAP_FAILED) goto fail;
 147                         if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
 148                                 munmap(map, size);
 149                                 goto fail;
 150                         }
 151                 } else {
 152                         map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
 153                         if (map == MAP_FAILED) goto fail;
 154                 }
 155                 tsd = map + size - __pthread_tsd_size;
 156                 if (!stack) {
 157                         stack = tsd - libc.tls_size;
 158                         stack_limit = map + guard;
 159                 }
 160         }
 161
 162         new = __copy_tls(tsd - libc.tls_size);
 163         new->map_base = map;
 164         new->map_size = size;
 165         new->stack = stack;
 166         new->stack_size = stack - stack_limit;
 167         new->pid = self->pid;
 168         new->errno_ptr = &new->errno_val;
 169         new->start = entry;
 170         new->start_arg = arg;
 171         new->self = new;
 172         new->tsd = (void *)tsd;
 173         if (attr._a_detach) {
 174                 new->detached = 1;
 175                 flags -= 0x200000;
 176         }
 177         if (attr._a_sched) {
 178                 do_sched = new->startlock[0] = 1;
 179                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
 180                         SIGALL_SET, self->sigmask, _NSIG/8);
 181         }
 182         new->unblock_cancel = self->cancel;
 183         new->canary = self->canary;
 184
 185         a_inc(&libc.threads_minus_1);
 186         ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
 187
 188         __release_ptc();
 189
 190         if (do_sched) {
 191                 __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
 192                         new->sigmask, 0, _NSIG/8);
 193         }
 194
 195         if (ret < 0) {
 196                 a_dec(&libc.threads_minus_1);
 197                 if (map) munmap(map, size);
 198                 return EAGAIN;
 199         }
 200
 201         if (do_sched) {
 202                 ret = __syscall(SYS_sched_setscheduler, new->tid,
 203                         attr._a_policy, &attr._a_prio);
 204                 a_store(new->startlock, ret<0 ? 2 : 0);
 205                 __wake(new->startlock, 1, 1);
 206                 if (ret < 0) return -ret;
 207         }
 208
 209         *res = new;
 210         return 0;
 211 fail:
 212         __release_ptc();
 213         return EAGAIN;
 214 }