[PATCH] staging: rtl8723bs: refactor rtw_aes_decrypt() to reduce nesting

[Lin YuChen <starpt.official@gmail.com>]

Improve code readability by refactoring rtw_aes_decrypt() to use
guard clauses and early exits. This reduces the maximum indentation
level and flattens the logic flow for key assignment and decryption.

Signed-off-by: Lin YuChen <starpt.official@gmail.com>
---
 drivers/staging/rtl8723bs/core/rtw_security.c | 91 ++++++++++---------
 1 file changed, 46 insertions(+), 45 deletions(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_security.c b/drivers/staging/rtl8723bs/core/rtw_security.c
index b489babe7432..9229e0a1c792 100644
--- a/drivers/staging/rtl8723bs/core/rtw_security.c
+++ b/drivers/staging/rtl8723bs/core/rtw_security.c
@@ -1213,69 +1213,70 @@ u32 rtw_aes_decrypt(struct adapter *padapter, u8 *precvframe)
 
 	pframe = (unsigned char *)((union recv_frame *)precvframe)->u.hdr.rx_data;
 	/* 4 start to encrypt each fragment */
-	if (prxattrib->encrypt == _AES_) {
-		stainfo = rtw_get_stainfo(&padapter->stapriv, &prxattrib->ta[0]);
-		if (stainfo) {
-			if (is_multicast_ether_addr(prxattrib->ra)) {
-				static unsigned long start;
-				static u32 no_gkey_bc_cnt;
-				static u32 no_gkey_mc_cnt;
+	if (prxattrib->encrypt != _AES_)
+		goto exit;
 
-				if (!psecuritypriv->binstallGrpkey) {
-					res = _FAIL;
+	stainfo = rtw_get_stainfo(&padapter->stapriv, &prxattrib->ta[0]);
+	if (!stainfo) {
+		res = _FAIL;
+		goto exit;
+	}
+	if (is_multicast_ether_addr(prxattrib->ra)) {
+		static unsigned long start;
+		static u32 no_gkey_bc_cnt;
+		static u32 no_gkey_mc_cnt;
 
-					if (start == 0)
-						start = jiffies;
+		if (!psecuritypriv->binstallGrpkey) {
+			res = _FAIL;
 
-					if (is_broadcast_mac_addr(prxattrib->ra))
-						no_gkey_bc_cnt++;
-					else
-						no_gkey_mc_cnt++;
+			if (start == 0)
+				start = jiffies;
 
-					if (jiffies_to_msecs(jiffies - start) > 1000) {
-						if (no_gkey_bc_cnt || no_gkey_mc_cnt) {
-							netdev_dbg(padapter->pnetdev,
-								   FUNC_ADPT_FMT " no_gkey_bc_cnt:%u, no_gkey_mc_cnt:%u\n",
-								   FUNC_ADPT_ARG(padapter),
-								   no_gkey_bc_cnt,
-								   no_gkey_mc_cnt);
-						}
-						start = jiffies;
-						no_gkey_bc_cnt = 0;
-						no_gkey_mc_cnt = 0;
-					}
-
-					goto exit;
-				}
+			if (is_broadcast_mac_addr(prxattrib->ra))
+				no_gkey_bc_cnt++;
+			else
+				no_gkey_mc_cnt++;
 
+			if (jiffies_to_msecs(jiffies - start) > 1000) {
 				if (no_gkey_bc_cnt || no_gkey_mc_cnt) {
 					netdev_dbg(padapter->pnetdev,
-						   FUNC_ADPT_FMT " gkey installed. no_gkey_bc_cnt:%u, no_gkey_mc_cnt:%u\n",
-						   FUNC_ADPT_ARG(padapter),
-						   no_gkey_bc_cnt,
+						   FUNC_ADPT_FMT " no_gkey_bc_cnt:%u, no_gkey_mc_cnt:%u\n",
+						   FUNC_ADPT_ARG(padapter), no_gkey_bc_cnt,
 						   no_gkey_mc_cnt);
 				}
-				start = 0;
+				start = jiffies;
 				no_gkey_bc_cnt = 0;
 				no_gkey_mc_cnt = 0;
-
-				prwskey = psecuritypriv->dot118021XGrpKey[prxattrib->key_index].skey;
-				if (psecuritypriv->dot118021XGrpKeyid != prxattrib->key_index) {
-					res = _FAIL;
-					goto exit;
-				}
-			} else {
-				prwskey = &stainfo->dot118021x_UncstKey.skey[0];
 			}
 
-			length = ((union recv_frame *)precvframe)->u.hdr.len - prxattrib->hdrlen - prxattrib->iv_len;
+			goto exit;
+		}
 
-			res = aes_decipher(prwskey, prxattrib->hdrlen, pframe, length);
+		if (no_gkey_bc_cnt || no_gkey_mc_cnt) {
+			netdev_dbg(padapter->pnetdev,
+				   FUNC_ADPT_FMT " gkey installed. no_gkey_bc_cnt:%u, no_gkey_mc_cnt:%u\n",
+				   FUNC_ADPT_ARG(padapter), no_gkey_bc_cnt,
+				   no_gkey_mc_cnt);
+		}
+		start = 0;
+		no_gkey_bc_cnt = 0;
+		no_gkey_mc_cnt = 0;
 
-		} else {
+		prwskey = psecuritypriv->dot118021XGrpKey[prxattrib->key_index]
+				  .skey;
+		if (psecuritypriv->dot118021XGrpKeyid != prxattrib->key_index) {
 			res = _FAIL;
+			goto exit;
 		}
+	} else {
+		prwskey = &stainfo->dot118021x_UncstKey.skey[0];
 	}
+
+	length = ((union recv_frame *)precvframe)->u.hdr.len -
+		 prxattrib->hdrlen - prxattrib->iv_len;
+
+	res = aes_decipher(prwskey, prxattrib->hdrlen, pframe, length);
+
 exit:
 	return res;
 }
-- 
2.34.1