bpf: minor cleanups in helpers

Some minor misc cleanups, f.e. use sizeof(__u32) instead of hardcoding
and in __bpf_skb_max_len(), I missed that we always have skb->dev valid
anyway, so we can drop the unneeded test for dev; also few more other
misc bits addressed here.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

kernel/bpf/helpers.c

@@ -126,7 +126,7 @@ static u64 bpf_get_current_pid_tgid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 {
 	struct task_struct *task = current;
 
-	if (!task)
+	if (unlikely(!task))
 		return -EINVAL;
 
 	return (u64) task->tgid << 32 | task->pid;
@@ -144,12 +144,12 @@ static u64 bpf_get_current_uid_gid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
 	kuid_t uid;
 	kgid_t gid;
 
-	if (!task)
+	if (unlikely(!task))
 		return -EINVAL;
 
 	current_uid_gid(&uid, &gid);
 	return (u64) from_kgid(&init_user_ns, gid) << 32 |
-		from_kuid(&init_user_ns, uid);
+		     from_kuid(&init_user_ns, uid);
 }
 
 const struct bpf_func_proto bpf_get_current_uid_gid_proto = {

net/core/filter.c

@@ -2010,8 +2010,7 @@ static u32 __bpf_skb_min_len(const struct sk_buff *skb)
 
 static u32 __bpf_skb_max_len(const struct sk_buff *skb)
 {
-	return skb->dev ? skb->dev->mtu + skb->dev->hard_header_len :
-	       65536;
+	return skb->dev->mtu + skb->dev->hard_header_len;
 }
 
 static int bpf_skb_grow_rcsum(struct sk_buff *skb, unsigned int new_len)
@@ -2605,7 +2604,7 @@ static bool __is_valid_xdp_access(int off, int size,
 		return false;
 	if (off % size != 0)
 		return false;
-	if (size != 4)
+	if (size != sizeof(__u32))
 		return false;
 
 	return true;
@@ -2727,7 +2726,7 @@ static u32 bpf_net_convert_ctx_access(enum bpf_access_type type, int dst_reg,
 					  dst_reg, src_reg, insn);
 
 	case offsetof(struct __sk_buff, cb[0]) ...
-		offsetof(struct __sk_buff, cb[4]):
+	     offsetof(struct __sk_buff, cb[4]):
 		BUILD_BUG_ON(FIELD_SIZEOF(struct qdisc_skb_cb, data) < 20);
 
 		prog->cb_access = 1;