cut out a syscall on thread creation in the case where guard size is 0

[musl] / src / thread / pthread_create.c

diff --git a/src/thread/pthread_create.c b/src/thread/pthread_create.c
index 9c24b84..7494a48 100644 (file)
--- a/src/thread/pthread_create.c
+++ b/src/thread/pthread_create.c
@@ -25,13 +25,16 @@ void __pthread_unwind_next(struct __ptcb *cb)
                }
        }
 
-       syscall4(__NR_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
+       /* Mark this thread dead before decrementing count */
+       self->dead = 1;
 
        if (!a_fetch_add(&libc.threads_minus_1, -1))
                exit(0);
 
-       if (self->detached && self->map_base)
+       if (self->detached && self->map_base) {
+               syscall4(__NR_rt_sigprocmask, SIG_BLOCK, (long)(uint64_t[1]){-1},0,8);
                __unmapself(self->map_base, self->map_size);
+       }
 
        __syscall_exit(0);
 }
@@ -76,9 +79,17 @@ static struct {
 
 static void rsyscall_handler(int sig, siginfo_t *si, void *ctx)
 {
-       if (si->si_code > 0 || si->si_pid != __pthread_self()->pid) return;
+       struct pthread *self = __pthread_self();
+
+       if (si->si_code > 0 || si->si_pid != self->pid ||
+               rs.cnt == libc.threads_minus_1) return;
 
-       if (rs.cnt == libc.threads_minus_1) return;
+       /* Threads which have already decremented themselves from the
+        * thread count must not increment rs.cnt or otherwise act. */
+       if (self->dead) {
+               __wait(&rs.hold, 0, 1, 1);
+               return;
+       }
 
        if (syscall6(rs.nr, rs.arg[0], rs.arg[1], rs.arg[2],
                rs.arg[3], rs.arg[4], rs.arg[5]) < 0 && !rs.err) rs.err=errno;
@@ -139,6 +150,7 @@ static void init_threads()
 {
        struct sigaction sa = { .sa_flags = SA_SIGINFO | SA_RESTART };
        libc.lock = __lock;
+       libc.lockfile = __lockfile;
        libc.cancelpt = cancelpt;
        libc.rsyscall = rsyscall;
        sa.sa_sigaction = cancel_handler;
@@ -183,7 +195,7 @@ int pthread_create(pthread_t *res, const pthread_attr_t *attr, void *(*entry)(vo
        size += __pthread_tsd_size;
        map = mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANON, -1, 0);
        if (!map) return EAGAIN;
-       mprotect(map, guard, PROT_NONE);
+       if (guard) mprotect(map, guard, PROT_NONE);
 
        tsd = map + size - __pthread_tsd_size;
        new = (void *)(tsd - sizeof *new - PAGE_SIZE%sizeof *new);