linux-kernel - [PATCH] iio: adc: stmpe-adc: Shuffle an if statement around in stmpe_adc

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Date:   Thu,  7 Mar 2019 10:16:04 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>,
        Lee Jones <lee.jones@...aro.org>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Stefan Agner <stefan@...er.ch>,
        Max Krummenacher <max.krummenacher@...adex.com>,
        Philippe Schenker <philippe.schenker@...adex.com>,
        linux-iio@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH] iio: adc: stmpe-adc: Shuffle an if statement around in stmpe_adc_isr

When building with -Wsometimes-uninitialized, Clang warns:

drivers/iio/adc/stmpe-adc.c:204:13: warning: variable 'data' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]

Clang can't tell that data will never be used uninitialized because the
two if statements take care of all cases. Remove the first if statement
and make it the else branch of the second one so that it is apparent to
Clang that all cases are covered.

Link: https://github.com/ClangBuiltLinux/linux/issues/387
Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/iio/adc/stmpe-adc.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
index 37f4b74a5d32..7921f827c6ec 100644
--- a/drivers/iio/adc/stmpe-adc.c
+++ b/drivers/iio/adc/stmpe-adc.c
@@ -184,9 +184,6 @@ static irqreturn_t stmpe_adc_isr(int irq, void *dev_id)
 	struct stmpe_adc *info = (struct stmpe_adc *)dev_id;
 	u16 data;
 
-	if (info->channel > STMPE_TEMP_CHANNEL)
-		return IRQ_NONE;
-
 	if (info->channel <= STMPE_ADC_LAST_NR) {
 		int int_sta;
 
@@ -205,6 +202,8 @@ static irqreturn_t stmpe_adc_isr(int irq, void *dev_id)
 		/* Read value */
 		stmpe_block_read(info->stmpe, STMPE_REG_TEMP_DATA, 2,
 				(u8 *) &data);
+	} else {
+		return IRQ_NONE;
 	}
 
 	info->value = (u32) be16_to_cpu(data);
-- 
2.21.0