[PATCH] iwlwifi: work around clang -Wuninitialized warning

[PATCH] iwlwifi: work around clang -Wuninitialized warning

[Arnd Bergmann]

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@arndb.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

Re: [PATCH] iwlwifi: work around clang -Wuninitialized warning

[Luca Coelho]

On Fri, 2019-03-22 at 15:13 +0100, Arnd Bergmann wrote:
> 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@arndb.de>
> ---

Thanks for the patch, Arnd! But I have already queued up an equivalent
patch for v5.2 (should probably reach linux-next by the end of next
week or so):

https://patchwork.kernel.org/patch/10844025/

--
Cheers,
Luca.

Re: [PATCH] iwlwifi: work around clang -Wuninitialized warning

[Arnd Bergmann]

On Sat, Mar 23, 2019 at 7:11 AM Luca Coelho <luca@coelho.fi> wrote:
>
> On Fri, 2019-03-22 at 15:13 +0100, Arnd Bergmann wrote:
> > Clang incorrectly warns about an uninitialized variable:
> >
> >
> > 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@arndb.de>
> > ---
>
> Thanks for the patch, Arnd! But I have already queued up an equivalent
> patch for v5.2 (should probably reach linux-next by the end of next
> week or so):
>
> https://patchwork.kernel.org/patch/10844025/

Thanks, and sorry for the duplicate. I forgot to check for the
patches that Nathan had already done when I started sending
out my own series on the same issues.

       Arnd