+static int iwl80211_get_cs_keyid(const struct ieee80211_cipher_scheme *cs,
+ struct sk_buff *skb)
+{
+ struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+ __le16 fc;
+ int hdrlen;
+ u8 keyid;
+
+ fc = hdr->frame_control;
+ hdrlen = ieee80211_hdrlen(fc);
+
+ if (skb->len < hdrlen + cs->hdr_len)
+ return -EINVAL;
+
+ skb_copy_bits(skb, hdrlen + cs->key_idx_off, &keyid, 1);
+ keyid &= cs->key_idx_mask;
+ keyid >>= cs->key_idx_shift;
+
+ return keyid;
+}
+