Here are five possible code completions for the given function:

**Option 1: Basic Implementation**
```c
static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
    if (level != SOL_NFC_LLCP) {
        return -EINVAL;
    }

    switch (optname) {
        case NFC_LLCP_OPTMI:
            // Handle NFC_LLCP_OPTMI option
            break;
        case NFC_LLCP_OPTMF:
            // Handle NFC_LLCP_OPTMF option
            break;
        default:
            return -EINVAL;
    }

    return 0;
}
```

**Option 2: With Error Handling**
```c
static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
    if (level != SOL_NFC_LLCP) {
        return -EINVAL;
    }

    if (!optval || optlen == 0) {
        return -EINVAL;
    }

    switch (optname) {
        case NFC_LLCP_OPTMI:
            // Handle NFC_LLCP_OPTMI option
            if (optlen != sizeof(int)) {
                return -EINVAL;
            }
            break;
        case NFC_LLCP_OPTMF:
            // Handle NFC_LLCP_OPTMF option
            if (optlen != sizeof(int)) {
                return -EINVAL;
            }
            break;
        default:
            return -EINVAL;
    }

    return 0;
}
```

**Option 3: With Locking Mechanism**
```c
static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
    int ret = 0;

    mutex_lock(&sock->sk_lock);

    if (level != SOL_NFC_LLCP) {
        ret = -EINVAL;
        goto out;
    }

    switch (optname) {
        case NFC_LLCP_OPTMI:
            // Handle NFC_LLCP_OPTMI option
            break;
        case NFC_LLCP_OPTMF:
            // Handle NFC_LLCP_OPTMF option
            break;
        default:
            ret = -EINVAL;
            goto out;
    }

out:
    mutex_unlock(&sock->sk_lock);
    return ret;
}
```

**Option 4: With Memory Allocation**
```c
static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
    int ret = 0;
    void *new_optval = NULL;

    if (level != SOL_NFC_LLCP) {
        return -EINVAL;
    }

    new_optval = kmalloc(optlen, GFP_KERNEL);
    if (!new_optval) {
        return -ENOMEM;
    }

    memcpy(new_optval, optval, optlen);

    switch (optname) {
        case NFC_LLCP_OPTMI:
            // Handle NFC_LLCP_OPTMI option
            break;
        case NFC_LLCP_OPTMF:
            // Handle NFC_LLCP_OPTMF option
            break;
        default:
            ret = -EINVAL;
            goto out;
    }

out:
    if (ret) {
        kfree(new_optval);
    }
    return ret;
}
```

**Option 5: With NFC LLCP Specific Options**
```c
static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
			       sockptr_t optval, unsigned int optlen)
{
    if (level != SOL_NFC_LLCP) {
        return -EINVAL;
    }

    switch (optname) {
        case NFC_LLCP_OPTMI:
            // Handle NFC_LLCP_OPTMI option
            if (optlen != sizeof(int)) {
                return -EINVAL;
            }
            sock->llcp_optmi = *(int *)optval;
            break;
        case NFC_LLCP_OPTMF:
            // Handle NFC_LLCP_OPTMF option
            if (optlen != sizeof(int)) {
                return -EINVAL;
            }
            sock->llcp_optmf = *(int *)optval;
            break;
        case NFC_LLCP_OPTSN:
            // Handle NFC_LLCP_OPTSN option
            if (optlen != sizeof(int)) {
                return -EINVAL;
            }
            sock->llcp_opts = *(int *)optval;
            break;
        default:
            return -EINVAL;
    }

    return 0;
}
```