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

   1 #include "pthread_impl.h"
   2 #include <setjmp.h>
   3
   4 struct thread {
   5         struct thread *next;
   6         pthread_t td;
   7         jmp_buf jb;
   8         void *tmp, *stack;
   9 };
  10
  11 struct ctx {
  12         struct thread *list;
  13         pthread_t caller;
  14         pid_t pid;
  15         size_t cnt;
  16         pthread_barrier_t barrier;
  17 };
  18
  19 static void restart_thread(pthread_t self)
  20 {
  21         struct thread *t = self->start_arg;
  22         self->start_arg = t->tmp;
  23         self->pid = getpid();
  24         longjmp(t->jb, 1);
  25 }
  26
  27 static void do_forkall(void *p)
  28 {
  29         struct ctx *c = p, *volatile cv = c;
  30         char tmpstack[2048];
  31         struct thread *tp, t = {
  32                 .td = __pthread_self(),
  33                 .next = c->list,
  34                 .stack = tmpstack+1024
  35         };
  36
  37         if (t.td != c->caller) {
  38                 c->cnt++;
  39                 t.tmp = t.td->start_arg;
  40                 t.td->start_arg = &t;
  41                 if (setjmp(t.jb)) {
  42                         c = cv;
  43                         if (c->pid) return;
  44                         pthread_barrier_wait(&c->barrier);
  45                         return;
  46                 }
  47                 c->list = &t;
  48                 __synccall_wait();
  49                 return;
  50         }
  51         c->pid = syscall(SYS_fork);
  52         if (c->pid) return;
  53
  54         pthread_barrier_init(&c->barrier, 0, c->cnt);
  55         for (tp=c->list; tp; tp=tp->next)
  56                 if (__uniclone(tp->stack, restart_thread, tp->td) < 0)
  57                         _exit(127);
  58         pthread_barrier_wait(&c->barrier);
  59 }
  60
  61 pid_t forkall()
  62 {
  63         struct ctx c = { .caller = pthread_self() };
  64         __synccall(do_forkall, &c);
  65         return c.pid;
  66 }