tools/sched_ext: fix getopt not re-parsed on restart

After goto restart, optind retains its advanced position from the
previous getopt loop, causing getopt() to immediately return -1.
This silently drops all command-line options on the restarted skeleton.

Reset optind to 1 at the restart label so options are re-parsed.

Affected schedulers: scx_simple, scx_central, scx_flatcg, scx_pair,
scx_sdt, scx_cpu0.

Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

tools/sched_ext/scx_central.c

@@ -56,6 +56,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(central_ops, scx_central);
 
 	skel->rodata->central_cpu = 0;

tools/sched_ext/scx_cpu0.c

@@ -69,6 +69,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(cpu0_ops, scx_cpu0);
 
 	skel->rodata->nr_cpus = libbpf_num_possible_cpus();

tools/sched_ext/scx_flatcg.c

@@ -141,6 +141,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(flatcg_ops, scx_flatcg);
 
 	skel->rodata->nr_cpus = libbpf_num_possible_cpus();

tools/sched_ext/scx_pair.c

@@ -53,6 +53,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(pair_ops, scx_pair);
 
 	skel->rodata->nr_cpu_ids = libbpf_num_possible_cpus();

tools/sched_ext/scx_sdt.c

@@ -51,6 +51,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(sdt_ops, scx_sdt);
 
 	while ((opt = getopt(argc, argv, "fvh")) != -1) {

tools/sched_ext/scx_simple.c

@@ -71,6 +71,7 @@ int main(int argc, char **argv)
 	signal(SIGINT, sigint_handler);
 	signal(SIGTERM, sigint_handler);
 restart:
+	optind = 1;
 	skel = SCX_OPS_OPEN(simple_ops, scx_simple);
 
 	while ((opt = getopt(argc, argv, "fvh")) != -1) {