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([2a0b:e7c0:0:107::49]) by smtp.gmail.com with ESMTPSA id s3sm422116ejv.97.2020.11.04.23.39.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Nov 2020 23:39:57 -0800 (PST) Subject: Re: [PATCH 34/36] tty: serial: pmac_zilog: Make disposable variable __always_unused To: Christophe Leroy , Lee Jones References: <20201104193549.4026187-1-lee.jones@linaro.org> <20201104193549.4026187-35-lee.jones@linaro.org> <445a6440-b4c8-4536-891b-0cefc78e5f57@csgroup.eu> From: Jiri Slaby Message-ID: Date: Thu, 5 Nov 2020 08:39:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.3 MIME-Version: 1.0 In-Reply-To: <445a6440-b4c8-4536-891b-0cefc78e5f57@csgroup.eu> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Greg Kroah-Hartman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Paul Mackerras , linux-serial@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 05. 11. 20, 8:04, Christophe Leroy wrote: > > > Le 04/11/2020 à 20:35, Lee Jones a écrit : >> Fixes the following W=1 kernel build warning(s): >> >> drivers/tty/serial/pmac_zilog.h:365:58: warning: variable ‘garbage’ >> set but not used [-Wunused-but-set-variable] > > Explain how you are fixing this warning. > > Setting __always_unused is usually not the good solution for fixing > this warning, but here I guess this is likely the good solution. But it > should be explained why. Or, why is the "garbage =" needed in the first place? read_zsdata is not defined with __warn_unused_result__. And even if it was, would (void)!read_zsdata(port) fix it? >> Cc: Greg Kroah-Hartman >> Cc: Jiri Slaby >> Cc: Michael Ellerman >> Cc: Benjamin Herrenschmidt >> Cc: Paul Mackerras >> Cc: linux-serial@vger.kernel.org >> Cc: linuxppc-dev@lists.ozlabs.org >> Signed-off-by: Lee Jones >> --- >> drivers/tty/serial/pmac_zilog.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/tty/serial/pmac_zilog.h >> b/drivers/tty/serial/pmac_zilog.h >> index bb874e76810e0..968aec7c1cf82 100644 >> --- a/drivers/tty/serial/pmac_zilog.h >> +++ b/drivers/tty/serial/pmac_zilog.h >> @@ -362,7 +362,7 @@ static inline void zssync(struct uart_pmac_port >> *port) >> /* Misc macros */ >> #define ZS_CLEARERR(port) (write_zsreg(port, 0, ERR_RES)) >> -#define ZS_CLEARFIFO(port) do { volatile unsigned char garbage; \ >> +#define ZS_CLEARFIFO(port) do { volatile unsigned char >> __always_unused garbage; \ >> garbage = read_zsdata(port); \ >> garbage = read_zsdata(port); \ >> garbage = read_zsdata(port); \ >> thanks, -- js