libbpf: Fix gen_loader assumption on number of programs.

libbpf's obj->nr_programs includes static and global functions. That number
could be higher than the actual number of bpf programs going be loaded by
gen_loader. Passing larger nr_programs to bpf_gen__init() doesn't hurt. Those
exra stack slots will stay as zero. bpf_gen__finish() needs to check that
actual number of progs that gen_loader saw is less than or equal to
obj->nr_programs.

Fixes: ba05fd3 ("libbpf: Perform map fd cleanup for gen_loader in case of error")
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: Alexei Starovoitov

tools/lib/bpf/gen_loader.c

@@ -371,8 +371,9 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
 {
 	int i;
 
-	if (nr_progs != gen->nr_progs || nr_maps != gen->nr_maps) {
-		pr_warn("progs/maps mismatch\n");
+	if (nr_progs < gen->nr_progs || nr_maps != gen->nr_maps) {
+		pr_warn("nr_progs %d/%d nr_maps %d/%d mismatch\n",
+			nr_progs, gen->nr_progs, nr_maps, gen->nr_maps);
 		gen->error = -EFAULT;
 		return gen->error;
 	}