linux-kernel - [PATCH] iwlwifi: work around clang -Wuninitialized warning

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Message-Id: <20190322141322.463149-1-arnd@arndb.de>
Date:   Fri, 22 Mar 2019 15:13:08 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Johannes Berg <johannes.berg@...el.com>
Cc:     clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Emmanuel Grumbach <emmanuel.grumbach@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Intel Linux Wireless <linuxwifi@...el.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Sara Sharon <sara.sharon@...el.com>,
        Avraham Stern <avraham.stern@...el.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] iwlwifi: work around clang -Wuninitialized warning

Clang incorrectly warns about an uninitialized variable:

drivers/net/wireless/intel/iwlwifi/mvm/sta.c:2114:12: error: variable 'queue' is used uninitialized whenever 'if'
      condition is false [-Werror,-Wsometimes-uninitialized]
                else if (WARN(1, "Missing required TXQ for adding bcast STA\n"))
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/asm-generic/bug.h:130:36: note: expanded from macro 'WARN'
 #define WARN(condition, format...) ({                                   \
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/intel/iwlwifi/mvm/sta.c:2119:33: note: uninitialized use occurs here
                iwl_mvm_enable_txq(mvm, NULL, queue, 0, &cfg, wdg_timeout);
                                              ^~~~~
drivers/net/wireless/intel/iwlwifi/mvm/sta.c:2114:8: note: remove the 'if' if its condition is always true
                else if (WARN(1, "Missing required TXQ for adding bcast STA\n"))
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/intel/iwlwifi/mvm/sta.c:2094:11: note: initialize the variable 'queue' to silence this warning
        int queue;
                 ^
                  = 0
1 error generated.

This cannot happen because the if/else if/else if block always
has one code path that is entered. However, we can simply
rearrange the code to let clang see this as well.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/net/wireless/intel/iwlwifi/mvm/sta.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
index 498c315291cf..91ce56d2ebb8 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/sta.c
@@ -2107,12 +2107,14 @@ int iwl_mvm_send_add_bcast_sta(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 
 	if (!iwl_mvm_has_new_tx_api(mvm)) {
 		if (vif->type == NL80211_IFTYPE_AP ||
-		    vif->type == NL80211_IFTYPE_ADHOC)
+		    vif->type == NL80211_IFTYPE_ADHOC) {
 			queue = mvm->probe_queue;
-		else if (vif->type == NL80211_IFTYPE_P2P_DEVICE)
+		} else if (vif->type == NL80211_IFTYPE_P2P_DEVICE) {
 			queue = mvm->p2p_dev_queue;
-		else if (WARN(1, "Missing required TXQ for adding bcast STA\n"))
+		} else {
+			WARN(1, "Missing required TXQ for adding bcast STA\n");
 			return -EINVAL;
+		}
 
 		bsta->tfd_queue_msk |= BIT(queue);
 
-- 
2.20.0