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SubjectRe: [PATCH] wireless: fix bogus maybe-uninitialized warning
Date
Arnd Bergmann <arnd@arndb.de> writes:

> The hostap_80211_rx() function is supposed to set up the mac addresses
> for four possible cases, based on two bits of input data. For
> some reason, gcc decides that it's possible that none of the these
> four cases apply and the addresses remain uninitialized:
>
> drivers/net/wireless/intersil/hostap/hostap_80211_rx.c: In function ‘hostap_80211_rx’:
> arch/x86/include/asm/string_32.h:77:14: warning: ‘src’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> drivers/net/wireless/intel/ipw2x00/libipw_rx.c: In function ‘libipw_rx’:
> arch/x86/include/asm/string_32.h:77:14: error: ‘dst’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> arch/x86/include/asm/string_32.h:78:22: error: ‘*((void *)&dst+4)’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> This warning is clearly nonsense, but changing the last case into
> 'default' makes it obvious to the compiler too, which avoids the
> warning and probably leads to better object code too.
>
> The same code is duplicated several times in the kernel, so this
> patch uses the same workaround for all copies. The exact configuration
> was hit only very rarely in randconfig builds and I only saw it
> in three drivers, but I assume that all of them are potentially
> affected, and it's better to keep the code consistent.
>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/net/wireless/ath/ath6kl/wmi.c | 8 ++++----
> drivers/net/wireless/intel/ipw2x00/libipw_rx.c | 2 +-
> drivers/net/wireless/intersil/hostap/hostap_80211_rx.c | 2 +-
> net/wireless/lib80211_crypt_tkip.c | 2 +-
> 4 files changed, 7 insertions(+), 7 deletions(-)

[...]

> --- a/net/wireless/lib80211_crypt_tkip.c
> +++ b/net/wireless/lib80211_crypt_tkip.c
> @@ -556,7 +556,7 @@ static void michael_mic_hdr(struct sk_buff *skb, u8 * hdr)
> memcpy(hdr, hdr11->addr3, ETH_ALEN); /* DA */
> memcpy(hdr + ETH_ALEN, hdr11->addr4, ETH_ALEN); /* SA */
> break;
> - case 0:
> + default:
> memcpy(hdr, hdr11->addr1, ETH_ALEN); /* DA */
> memcpy(hdr + ETH_ALEN, hdr11->addr2, ETH_ALEN); /* SA */
> break;

Ideally we prefer that drivers/net/wireless and net/wireless changes are
split into different patches as they get applied to different trees.
Johannes, is it ok if I take this change through my tree this time?

--
Kalle Valo

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