linux-kernel - [PATCH] scsi: gdth: Only call dma_free_coherent when buf is not NULL in ioc

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Date:   Thu,  7 Mar 2019 16:18:39 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Achim Leubner <achim_leubner@...ptec.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH] scsi: gdth: Only call dma_free_coherent when buf is not NULL in ioc_general

When building with -Wsometimes-uninitialized, Clang warns:

drivers/scsi/gdth.c:3662:6: warning: variable 'paddr' is used
uninitialized whenever 'if' condition is false
[-Wsometimes-uninitialized]

Don't attempt to call dma_free_coherent when buf is NULL (meaning that
we never called dma_alloc_coherent and initialized paddr), which avoids
this warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/402
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/scsi/gdth.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c
index e7f1dd4f3b66..0ca9b4393770 100644
--- a/drivers/scsi/gdth.c
+++ b/drivers/scsi/gdth.c
@@ -3697,8 +3697,9 @@ static int ioc_general(void __user *arg, char *cmnd)
 
 	rval = 0;
 out_free_buf:
-	dma_free_coherent(&ha->pdev->dev, gen.data_len + gen.sense_len, buf,
-			paddr);
+	if (buf)
+		dma_free_coherent(&ha->pdev->dev, gen.data_len + gen.sense_len,
+				  buf, paddr);
 	return rval;
 }
  
-- 
2.21.0