cfg80211: fix ieee80211_get_vht_max_nss()

Fix two bugs in ieee80211_get_vht_max_nss():
 * the spec says we should round down
   (reported by Nissim)
 * there's a double condition, the first one is wrong,
   supp_width == 0 / ext_nss_bw == 2 is valid in 80+80
   (found by smatch)

Fixes: b0aa75f0b1b2 ("ieee80211: add new VHT capability fields/parsing")
Reported-by: Nissim Bendanan <nissimx.bendanan@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/util.c b/net/wireless/util.c
index ef14d80..06a0842 100644 (file)
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -2013,33 +2013,32 @@ int ieee80211_get_vht_max_nss(struct ieee80211_vht_cap *cap,
        case IEEE80211_VHT_CHANWIDTH_160MHZ:
                if (supp_width == 0 &&
                    (ext_nss_bw == 1 || ext_nss_bw == 2))
-                       return DIV_ROUND_UP(max_vht_nss, 2);
+                       return max_vht_nss / 2;
                if (supp_width == 0 &&
                    ext_nss_bw == 3)
-                       return DIV_ROUND_UP(3 * max_vht_nss, 4);
+                       return (3 * max_vht_nss) / 4;
                if (supp_width == 1 &&
                    ext_nss_bw == 3)
                        return 2 * max_vht_nss;
                break;
        case IEEE80211_VHT_CHANWIDTH_80P80MHZ:
-               if (supp_width == 0 &&
-                   (ext_nss_bw == 1 || ext_nss_bw == 2))
+               if (supp_width == 0 && ext_nss_bw == 1)
                        return 0; /* not possible */
                if (supp_width == 0 &&
                    ext_nss_bw == 2)
-                       return DIV_ROUND_UP(max_vht_nss, 2);
+                       return max_vht_nss / 2;
                if (supp_width == 0 &&
                    ext_nss_bw == 3)
-                       return DIV_ROUND_UP(3 * max_vht_nss, 4);
+                       return (3 * max_vht_nss) / 4;
                if (supp_width == 1 &&
                    ext_nss_bw == 0)
                        return 0; /* not possible */
                if (supp_width == 1 &&
                    ext_nss_bw == 1)
-                       return DIV_ROUND_UP(max_vht_nss, 2);
+                       return max_vht_nss / 2;
                if (supp_width == 1 &&
                    ext_nss_bw == 2)
-                       return DIV_ROUND_UP(3 * max_vht_nss, 4);
+                       return (3 * max_vht_nss) / 4;
                break;
        }