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

   1 #include "pthread_impl.h"
   2 #include "stdio_impl.h"
   3
   4 static void dummy_0()
   5 {
   6 }
   7 weak_alias(dummy_0, __synccall_lock);
   8 weak_alias(dummy_0, __synccall_unlock);
   9 weak_alias(dummy_0, __pthread_tsd_run_dtors);
  10
  11 void pthread_exit(void *result)
  12 {
  13         pthread_t self = pthread_self();
  14         int n;
  15
  16         self->result = result;
  17
  18         while (self->cancelbuf) {
  19                 void (*f)(void *) = self->cancelbuf->__f;
  20                 void *x = self->cancelbuf->__x;
  21                 self->cancelbuf = self->cancelbuf->__next;
  22                 f(x);
  23         }
  24
  25         __pthread_tsd_run_dtors();
  26
  27         __lock(&self->exitlock);
  28
  29         /* Mark this thread dead before decrementing count */
  30         __lock(&self->killlock);
  31         self->dead = 1;
  32         a_store(&self->killlock, 0);
  33
  34         do n = libc.threads_minus_1;
  35         while (n && a_cas(&libc.threads_minus_1, n, n-1)!=n);
  36         if (!n) exit(0);
  37
  38         if (self->detached && self->map_base) {
  39                 __syscall(SYS_rt_sigprocmask, SIG_BLOCK, (uint64_t[]){-1},0,8);
  40                 __unmapself(self->map_base, self->map_size);
  41         }
  42
  43         __syscall(SYS_exit, 0);
  44 }
  45
  46 void __do_cleanup_push(struct __ptcb *cb)
  47 {
  48         struct pthread *self = pthread_self();
  49         cb->__next = self->cancelbuf;
  50         self->cancelbuf = cb;
  51 }
  52
  53 void __do_cleanup_pop(struct __ptcb *cb)
  54 {
  55         __pthread_self()->cancelbuf = cb->__next;
  56 }
  57
  58 static int start(void *p)
  59 {
  60         pthread_t self = p;
  61         if (self->unblock_cancel)
  62                 __syscall(SYS_rt_sigprocmask, SIG_UNBLOCK, SIGPT_SET, 0, 8);
  63         pthread_exit(self->start(self->start_arg));
  64         return 0;
  65 }
  66
  67 #define ROUND(x) (((x)+PAGE_SIZE-1)&-PAGE_SIZE)
  68
  69 /* pthread_key_create.c overrides this */
  70 static const size_t dummy = 0;
  71 weak_alias(dummy, __pthread_tsd_size);
  72
  73 static FILE *const dummy_file = 0;
  74 weak_alias(dummy_file, __stdin_used);
  75 weak_alias(dummy_file, __stdout_used);
  76 weak_alias(dummy_file, __stderr_used);
  77
  78 static void init_file_lock(FILE *f)
  79 {
  80         if (f && f->lock<0) f->lock = 0;
  81 }
  82
  83 int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(void *), void *arg)
  84 {
  85         int ret;
  86         size_t size = DEFAULT_STACK_SIZE + DEFAULT_GUARD_SIZE;
  87         size_t guard = DEFAULT_GUARD_SIZE;
  88         struct pthread *self = pthread_self(), *new;
  89         unsigned char *map, *stack, *tsd;
  90
  91         if (!self) return ENOSYS;
  92         if (!libc.threaded) {
  93                 for (FILE *f=libc.ofl_head; f; f=f->next)
  94                         init_file_lock(f);
  95                 init_file_lock(__stdin_used);
  96                 init_file_lock(__stdout_used);
  97                 init_file_lock(__stderr_used);
  98                 libc.threaded = 1;
  99         }
 100
 101         if (attr) {
 102                 guard = ROUND(attr->_a_guardsize + DEFAULT_GUARD_SIZE);
 103                 size = guard + ROUND(attr->_a_stacksize + DEFAULT_STACK_SIZE);
 104         }
 105         size += __pthread_tsd_size;
 106         map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
 107         if (map == MAP_FAILED) return EAGAIN;
 108         if (guard) mprotect(map, guard, PROT_NONE);
 109
 110         tsd = map + size - __pthread_tsd_size;
 111         new = (void *)(tsd - sizeof *new - PAGE_SIZE%sizeof *new);
 112         new->map_base = map;
 113         new->map_size = size;
 114         new->pid = self->pid;
 115         new->errno_ptr = &new->errno_val;
 116         new->start = entry;
 117         new->start_arg = arg;
 118         new->self = new;
 119         new->tsd = (void *)tsd;
 120         if (attr) new->detached = attr->_a_detach;
 121         new->unblock_cancel = self->cancel;
 122         new->canary = self->canary ^ (uintptr_t)&new;
 123         stack = (void *)new;
 124
 125         __synccall_lock();
 126
 127         a_inc(&libc.threads_minus_1);
 128         ret = __clone(start, stack, 0x7d8f00, new, &new->tid, new, &new->tid);
 129
 130         __synccall_unlock();
 131
 132         if (ret < 0) {
 133                 a_dec(&libc.threads_minus_1);
 134                 munmap(map, size);
 135                 return EAGAIN;
 136         }
 137         *res = new;
 138         return 0;
 139 }