From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kalle Valo Subject: Re: [PATCH] ath10k: avoid -Wmaybe-uninitialized warning Date: Fri, 16 Nov 2018 11:55:27 +0200 Message-ID: <87sh0173e8.fsf@codeaurora.org> References: <20181102161833.2956376-1-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain Cc: Arnd Bergmann , srirrama@codeaurora.org, bpothuno@codeaurora.org, akolli@codeaurora.org, linux-wireless@vger.kernel.org, Linux Kernel , yintang@qti.qualcomm.com, pillair@codeaurora.org, ath10k@lists.infradead.org, netdev@vger.kernel.org, davem@davemloft.net To: Brian Norris Return-path: In-Reply-To: (Brian Norris's message of "Fri, 2 Nov 2018 09:34:53 -0700") Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Brian Norris writes: > Hi, > > On Fri, Nov 2, 2018 at 9:19 AM Arnd Bergmann wrote: >> >> In some configurations the inlining in gcc is suboptimal, causing >> a false-positive warning: >> >> drivers/net/wireless/ath/ath10k/mac.c: In function 'ath10k_mac_init_rd': >> drivers/net/wireless/ath/ath10k/mac.c:8374:39: error: 'rd' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> ar->ath_common.regulatory.current_rd = rd; >> >> If we initialize the output of ath10k_mac_get_wrdd_regulatory() >> before returning, this problem goes away. >> >> Fixes: 209b2a68de76 ("ath10k: add platform regulatory domain support") >> Signed-off-by: Arnd Bergmann >> --- >> drivers/net/wireless/ath/ath10k/mac.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/net/wireless/ath/ath10k/mac.c b/drivers/net/wireless/ath/ath10k/mac.c >> index a1c2801ded10..0d5fde28ee44 100644 >> --- a/drivers/net/wireless/ath/ath10k/mac.c >> +++ b/drivers/net/wireless/ath/ath10k/mac.c >> @@ -8321,6 +8321,8 @@ static int ath10k_mac_get_wrdd_regulatory(struct ath10k *ar, u16 *rd) >> u32 alpha2_code; >> char alpha2[3]; >> >> + *rd = ar->hw_eeprom_rd; >> + > > Maybe it's just me, but it seems kinda weird for this function to > assign a (valid) value to its "output" and still potentially return an > error. > > If you really need to work around this compiler bug, maybe just put > the eeprom assignment back in ath10k_mac_init_rd()? I'll leave it up > to Kalle as to whether he wants to work around the compiler at all :) In general I'm happy take workaround to compiler problems, I prefer to keep ath10k warning free much as possible. > Oh wait, one more thing: this is actually an invalid refactoring. See > how this function assigns '*rd' later in error cases. Today, we still > treat those as errors and clobber those with the eeprom value, but > now, you're making the fallback case continue to use the erroneous > value (0xffff). You need to make that use a local variable and avoid > clobbering *rd, if you want this to be correct. But I agree with Brian here, I don't think this patch is correct. -- Kalle Valo