bpf: Remove now-unnecessary NULL checks for KF_RELEASE kfuncs

Now that we're not invoking kfunc destructors when the kptr in a map was
NULL, we no longer require NULL checks in many of our KF_RELEASE kfuncs.
This patch removes those NULL checks.
Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230325213144.486885-3-void@manifault.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

drivers/hid/bpf/hid_bpf_dispatch.c

@@ -342,9 +342,6 @@ hid_bpf_release_context(struct hid_bpf_ctx *ctx)
 {
 	struct hid_bpf_ctx_kern *ctx_kern;
 
-	if (!ctx)
-		return;
-
 	ctx_kern = container_of(ctx, struct hid_bpf_ctx_kern, ctx);
 
 	kfree(ctx_kern);

kernel/bpf/cpumask.c

@@ -102,9 +102,6 @@ static void cpumask_free_cb(struct rcu_head *head)
  */
 __bpf_kfunc void bpf_cpumask_release(struct bpf_cpumask *cpumask)
 {
-	if (!cpumask)
-		return;
-
 	if (refcount_dec_and_test(&cpumask->usage))
 		call_rcu(&cpumask->rcu, cpumask_free_cb);
 }

kernel/bpf/helpers.c

@@ -2089,9 +2089,6 @@ __bpf_kfunc struct task_struct *bpf_task_kptr_get(struct task_struct **pp)
  */
 __bpf_kfunc void bpf_task_release(struct task_struct *p)
 {
-	if (!p)
-		return;
-
 	put_task_struct(p);
 }
 
@@ -2148,9 +2145,6 @@ __bpf_kfunc struct cgroup *bpf_cgroup_kptr_get(struct cgroup **cgrpp)
  */
 __bpf_kfunc void bpf_cgroup_release(struct cgroup *cgrp)
 {
-	if (!cgrp)
-		return;
-
 	cgroup_put(cgrp);
 }
 

net/bpf/test_run.c

@@ -615,9 +615,6 @@ bpf_kfunc_call_memb_acquire(void)
 
 __bpf_kfunc void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p)
 {
-	if (!p)
-		return;
-
 	refcount_dec(&p->cnt);
 }
 

net/netfilter/nf_conntrack_bpf.c

@@ -401,8 +401,6 @@ __bpf_kfunc struct nf_conn *bpf_ct_insert_entry(struct nf_conn___init *nfct_i)
  */
 __bpf_kfunc void bpf_ct_release(struct nf_conn *nfct)
 {
-	if (!nfct)
-		return;
 	nf_ct_put(nfct);
 }