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From:   Nathan Chancellor <nathan@kernel.org>
To:     Codrin Ciubotariu <codrin.ciubotariu@microchip.com>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Claudiu Beznea <claudiu.beznea@microchip.com>,
        Wolfram Sang <wsa@kernel.org>, Michael Walle <michael@walle.cc>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-i2c@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH] i2c: at91: Initialize dma_buf in at91_twi_xfer()
Date:   Thu,  5 May 2022 08:27:38 -0700
Message-Id: <20220505152738.1440249-1-nathan@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Clang warns:

  drivers/i2c/busses/i2c-at91-master.c:707:6: warning: variable 'dma_buf' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
          if (dev->use_dma) {
              ^~~~~~~~~~~~
  drivers/i2c/busses/i2c-at91-master.c:717:27: note: uninitialized use occurs here
          i2c_put_dma_safe_msg_buf(dma_buf, m_start, !ret);
                                   ^~~~~~~

Initialize dma_buf to NULL, as i2c_put_dma_safe_msg_buf() is a no-op
when the first argument is NULL, which will work for the !dev->use_dma
case.

Fixes: 03fbb903c8bf ("i2c: at91: use dma safe buffers")
Link: https://github.com/ClangBuiltLinux/linux/issues/1629
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/i2c/busses/i2c-at91-master.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index 5eca3b3bb609..c0c35785a0dc 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -656,7 +656,7 @@ static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
 	unsigned int_addr_flag = 0;
 	struct i2c_msg *m_start = msg;
 	bool is_read;
-	u8 *dma_buf;
+	u8 *dma_buf = NULL;
 
 	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
 

base-commit: a181b8d187319bf265a2019ddde856a3d2f107a6
-- 
2.36.0