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, __SYSCALL_SSLEN);
  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, __SYSCALL_SSLEN);
  73         }
  74         if (self->unblock_cancel)
  75                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK,
  76                         SIGPT_SET, 0, __SYSCALL_SSLEN);
  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 attr, void *(*entry)(void *), void *restrict arg)
 100 {
 101         int ret;
 102         size_t size = DEFAULT_STACK_SIZE + DEFAULT_GUARD_SIZE;
 103         size_t guard = DEFAULT_GUARD_SIZE;
 104         struct pthread *self = pthread_self(), *new;
 105         unsigned char *map, *stack, *tsd;
 106         unsigned flags = 0x7d8f00;
 107         int do_sched = 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
 119         __acquire_ptc();
 120
 121         if (attr && attr->_a_stackaddr) {
 122                 map = 0;
 123                 tsd = (void *)(attr->_a_stackaddr-__pthread_tsd_size & -16);
 124         } else {
 125                 if (attr) {
 126                         guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
 127                         size = guard + ROUND(attr->_a_stacksize
 128                                 + DEFAULT_STACK_SIZE + libc.tls_size);
 129                 }
 130                 size += __pthread_tsd_size;
 131                 if (guard) {
 132                         map = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANON, -1, 0);
 133                         if (map == MAP_FAILED) return EAGAIN;
 134                         if (mprotect(map+guard, size-guard, PROT_READ|PROT_WRITE)) {
 135                                 munmap(map, size);
 136                                 return EAGAIN;
 137                         }
 138                 } else {
 139                         map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
 140                         if (map == MAP_FAILED) return EAGAIN;
 141                 }
 142                 tsd = map + size - __pthread_tsd_size;
 143         }
 144         new = __copy_tls(stack = tsd - libc.tls_size);
 145         new->map_base = map;
 146         new->map_size = size;
 147         new->pid = self->pid;
 148         new->errno_ptr = &new->errno_val;
 149         new->start = entry;
 150         new->start_arg = arg;
 151         new->self = new;
 152         new->tsd = (void *)tsd;
 153         if (attr && attr->_a_detach) {
 154                 new->detached = 1;
 155                 flags -= 0x200000;
 156         }
 157         if (attr && attr->_a_sched) {
 158                 do_sched = new->startlock[0] = 1;
 159                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK,
 160                         SIGALL_SET, self->sigmask, __SYSCALL_SSLEN);
 161         }
 162         new->unblock_cancel = self->cancel;
 163         new->canary = self->canary;
 164
 165         a_inc(&libc.threads_minus_1);
 166         ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
 167
 168         __release_ptc();
 169
 170         if (do_sched) {
 171                 __syscall(SYS_rt_sigprocmask, SIG_SETMASK,
 172                         new->sigmask, 0, __SYSCALL_SSLEN);
 173         }
 174
 175         if (ret < 0) {
 176                 a_dec(&libc.threads_minus_1);
 177                 munmap(map, size);
 178                 return EAGAIN;
 179         }
 180
 181         if (do_sched) {
 182                 ret = __syscall(SYS_sched_setscheduler, new->tid,
 183                         attr->_a_policy, &attr->_a_prio);
 184                 a_store(new->startlock, ret<0 ? 2 : 0);
 185                 __wake(new->startlock, 1, 1);
 186                 if (ret < 0) return -ret;
 187         }
 188
 189         *res = new;
 190         return 0;
 191 }