netdev - -Wsometimes-uninitialized warning after 8b97b055dc9db09b48d5a9a37d847900dd00d3cc

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Message-ID: <20190702181837.GA118849@archlinux-epyc>
Date:   Tue, 2 Jul 2019 11:18:37 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Miaoqing Pan <miaoqing@...eaurora.org>,
        Kalle Valo <kvalo@...eaurora.org>
Cc:     ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: -Wsometimes-uninitialized warning after
 8b97b055dc9db09b48d5a9a37d847900dd00d3cc

Hi all,

After commit 8b97b055dc9d ("ath10k: fix failure to set multiple fixed
rate") in -next, clang warns:

../drivers/net/wireless/ath/ath10k/mac.c:7528:7: warning: variable 'vht_pfr' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                if (!ath10k_mac_can_set_bitrate_mask(ar, band, mask,
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/net/wireless/ath/ath10k/mac.c:7551:20: note: uninitialized use occurs here
                arvif->vht_pfr = vht_pfr;
                                 ^~~~~~~
../drivers/net/wireless/ath/ath10k/mac.c:7528:3: note: remove the 'if' if its condition is always true
                if (!ath10k_mac_can_set_bitrate_mask(ar, band, mask,
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../drivers/net/wireless/ath/ath10k/mac.c:7483:12: note: initialize the variable 'vht_pfr' to silence this warning
        u8 vht_pfr;
                  ^
                   = '\0'
1 warning generated.

This definitely seems legitimate as the call to
ath10k_mac_can_set_bitrate_mask might fail and vht_pfr
won't be initialized. I would fix this myself but I assume
there is a sane default value for vht_pfr other than just
0 that should be used?

Please look into this when you get a chance. Thanks,
Nathan