[PATCH][next] rndis_wlan: Remove logically dead code

[Gustavo A. R. Silva]

caps_buf is always of size sizeof(*caps) because
sizeof(caps->auth_encr_pair) * 16 is always zero. Notice
that when using zero-length arrays, sizeof evaluates to zero[1].

So, the code introduced by 
commit 0308383f9591 ("rndis_wlan: get max_num_pmkids from device")
is logically dead, hence is never executed and can be removed. As a
consequence, the rest of the related code can be refactored a bit.

Notice that this code has been out there since March 2010.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
---
In case this is actually a 10-year old bug, then we might want
calculate the size of caps_buf through the use of the struct_size
helper:

struct_size(caps, auth_encr_pair, 16);

and we might also want to allocate dynamic memory instead, as we
cannot do u8 caps_buf[struct_size(caps, auth_encr_pair, 16)];
due to -Wvla.

Thanks
--
Gustavo

 drivers/net/wireless/rndis_wlan.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/rndis_wlan.c 
b/drivers/net/wireless/rndis_wlan.c
index 52375f3e430a..8852a1832951 100644
--- a/drivers/net/wireless/rndis_wlan.c
+++ b/drivers/net/wireless/rndis_wlan.c
@@ -312,17 +312,11 @@ struct ndis_80211_assoc_info {
        __le32 offset_resp_ies;
 } __packed;
 
-struct ndis_80211_auth_encr_pair {
-       __le32 auth_mode;
-       __le32 encr_mode;
-} __packed;
-
 struct ndis_80211_capability {
        __le32 length;
        __le32 version;
        __le32 num_pmkids;
        __le32 num_auth_encr_pair;
-       struct ndis_80211_auth_encr_pair auth_encr_pair[0];
 } __packed;
 
 struct ndis_80211_bssid_info {
@@ -3109,8 +3103,7 @@ static int rndis_wlan_get_caps(struct usbnet *usbdev, 
struct wiphy *wiphy)
                __le32  num_items;
                __le32  items[8];
        } networks_supported;
-       struct ndis_80211_capability *caps;
-       u8 caps_buf[sizeof(*caps) + sizeof(caps->auth_encr_pair) * 16];
+       struct ndis_80211_capability caps;
        int len, retval, i, n;
        struct rndis_wlan_private *priv = get_rndis_wlan_priv(usbdev);
 
@@ -3140,19 +3133,18 @@ static int rndis_wlan_get_caps(struct usbnet *usbdev, 
struct wiphy *wiphy)
        }
 
        /* get device 802.11 capabilities, number of PMKIDs */
-       caps = (struct ndis_80211_capability *)caps_buf;
-       len = sizeof(caps_buf);
+       len = sizeof(caps);
        retval = rndis_query_oid(usbdev,
                                 RNDIS_OID_802_11_CAPABILITY,
-                                caps, &len);
+                                &caps, &len);
        if (retval >= 0) {
                netdev_dbg(usbdev->net, "RNDIS_OID_802_11_CAPABILITY -> len %d, 
"
                                "ver %d, pmkids %d, auth-encr-pairs %d\n",
-                               le32_to_cpu(caps->length),
-                               le32_to_cpu(caps->version),
-                               le32_to_cpu(caps->num_pmkids),
-                               le32_to_cpu(caps->num_auth_encr_pair));
-               wiphy->max_num_pmkids = le32_to_cpu(caps->num_pmkids);
+                               le32_to_cpu(caps.length),
+                               le32_to_cpu(caps.version),
+                               le32_to_cpu(caps.num_pmkids),
+                               le32_to_cpu(caps.num_auth_encr_pair));
+               wiphy->max_num_pmkids = le32_to_cpu(caps.num_pmkids);
        } else
                wiphy->max_num_pmkids = 0;
 
-- 
2.26.2