selftests/bpf: fix lots of silly mistakes pointed out by compiler

Once we enable -Wall for BPF sources, compiler will complain about lots
of unused variables, variables that are set but never read, etc.

Fix all these issues first before enabling -Wall in Makefile.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230309054015.4068562-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: anakryiko

tools/testing/selftests/bpf/progs/bpf_iter_ksym.c

@@ -33,7 +33,6 @@ int dump_ksym(struct bpf_iter__ksym *ctx)
 	__u32 seq_num = ctx->meta->seq_num;
 	unsigned long value;
 	char type;
-	int ret;
 
 	if (!iter)
 		return 0;

tools/testing/selftests/bpf/progs/bpf_iter_setsockopt.c

@@ -42,7 +42,6 @@ int change_tcp_cc(struct bpf_iter__tcp *ctx)
 	char cur_cc[TCP_CA_NAME_MAX];
 	struct tcp_sock *tp;
 	struct sock *sk;
-	int ret;
 
 	if (!bpf_tcp_sk(ctx->sk_common))
 		return 0;

tools/testing/selftests/bpf/progs/bpf_loop.c

@@ -138,8 +138,6 @@ static int callback_set_0f(int i, void *ctx)
 SEC("fentry/" SYS_PREFIX "sys_nanosleep")
 int prog_non_constant_callback(void *ctx)
 {
-	struct callback_ctx data = {};
-
 	if (bpf_get_current_pid_tgid() >> 32 != pid)
 		return 0;
 

tools/testing/selftests/bpf/progs/cb_refs.c

@@ -52,7 +52,6 @@ int leak_prog(void *ctx)
 {
 	struct prog_test_ref_kfunc *p;
 	struct map_value *v;
-	unsigned long sl;
 
 	v = bpf_map_lookup_elem(&array_map, &(int){0});
 	if (!v)

tools/testing/selftests/bpf/progs/cgroup_skb_sk_lookup_kern.c

@@ -66,7 +66,6 @@ static inline int is_allowed_peer_cg(struct __sk_buff *skb,
 SEC("cgroup_skb/ingress")
 int ingress_lookup(struct __sk_buff *skb)
 {
-	__u32 serv_port_key = 0;
 	struct ipv6hdr ip6h;
 	struct tcphdr tcph;
 

tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c

@@ -109,6 +109,7 @@ int BPF_PROG(cgrp_kfunc_acquire_unreleased, struct cgroup *cgrp, const char *pat
 	acquired = bpf_cgroup_acquire(cgrp);
 
 	/* Acquired cgroup is never released. */
+	__sink(acquired);
 
 	return 0;
 }

tools/testing/selftests/bpf/progs/cgrp_ls_attach_cgroup.c

@@ -84,7 +84,6 @@ int BPF_PROG(update_cookie_tracing, struct socket *sock,
 	     struct sockaddr *uaddr, int addr_len, int flags)
 {
 	struct socket_cookie *p;
-	struct tcp_sock *tcp_sk;
 
 	if (uaddr->sa_family != AF_INET6)
 		return 0;

tools/testing/selftests/bpf/progs/cgrp_ls_sleepable.c

@@ -24,7 +24,6 @@ void bpf_rcu_read_unlock(void) __ksym;
 SEC("?iter.s/cgroup")
 int cgroup_iter(struct bpf_iter__cgroup *ctx)
 {
-	struct seq_file *seq = ctx->meta->seq;
 	struct cgroup *cgrp = ctx->cgroup;
 	long *ptr;
 

tools/testing/selftests/bpf/progs/core_kern.c

@@ -77,7 +77,7 @@ int balancer_ingress(struct __sk_buff *ctx)
 	void *data_end = (void *)(long)ctx->data_end;
 	void *data = (void *)(long)ctx->data;
 	void *ptr;
-	int ret = 0, nh_off, i = 0;
+	int nh_off, i = 0;
 
 	nh_off = 14;
 

tools/testing/selftests/bpf/progs/cpumask_failure.c

@@ -23,6 +23,7 @@ int BPF_PROG(test_alloc_no_release, struct task_struct *task, u64 clone_flags)
 	struct bpf_cpumask *cpumask;
 
 	cpumask = create_cpumask();
+	__sink(cpumask);
 
 	/* cpumask is never released. */
 	return 0;
@@ -51,6 +52,7 @@ int BPF_PROG(test_acquire_wrong_cpumask, struct task_struct *task, u64 clone_fla
 
 	/* Can't acquire a non-struct bpf_cpumask. */
 	cpumask = bpf_cpumask_acquire((struct bpf_cpumask *)task->cpus_ptr);
+	__sink(cpumask);
 
 	return 0;
 }
@@ -63,6 +65,7 @@ int BPF_PROG(test_mutate_cpumask, struct task_struct *task, u64 clone_flags)
 
 	/* Can't set the CPU of a non-struct bpf_cpumask. */
 	bpf_cpumask_set_cpu(0, (struct bpf_cpumask *)task->cpus_ptr);
+	__sink(cpumask);
 
 	return 0;
 }