libthread: deal with _schedfork() and _schedexec() returning -1

The current behaviour of the kernel to deadlock itself
instead of returning an error on fork.

This might change in the future, so prepare libthread
to handle this case.

For _schedfork(), we'r going to just retry forking
on every switch, while for _schedexec(), the exec
will fail and send ~0 down the pid channel.

1 files changed, 5 insertions, 1 deletions

diff --git a/sys/src/libthread/exec.c b/sys/src/libthread/exec.c
index 3bfbda3c6..b3ac6c213 100644
--- a/sys/src/libthread/exec.c
+++ b/sys/src/libthread/exec.c
@@ -45,8 +45,10 @@ procexec(Channel *pidc, char *prog, char *args[])
 	close(p->exec.fd[1]);
 	p->exec.fd[1] = n;
 
+	while(p->needexec || p->newproc)
+		_sched();
+
 	/* exec in parallel via the scheduler */
-	assert(p->needexec==0);
 	p->exec.prog = prog;
 	p->exec.args = args;
 	p->needexec = 1;
@@ -61,6 +63,8 @@ procexec(Channel *pidc, char *prog, char *args[])
 	}
 	close(p->exec.fd[0]);
 
+	if(t->ret == -1)
+		goto Bad;
 	if(pidc)
 		sendul(pidc, t->ret);