linux-kernel - [PATCH 5.17 578/772] i2c: at91: Initialize dma_buf in at91_twi

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Message-Id: <20220607165005.982225958@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 19:02:50 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
        Michael Walle <michael@...le.cc>,
        Wolfram Sang <wsa@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 578/772] i2c: at91: Initialize dma_buf in at91_twi_xfer()

From: Nathan Chancellor <nathan@...nel.org>

[ Upstream commit 6977262c2eee111645668fe9e235ef2f5694abf7 ]

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@...nel.org>
Reviewed-by: Michael Walle <michael@...le.cc>
Signed-off-by: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.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);
 
-- 
2.35.1