linux-kernel - [PATCH] video: radeon.h Fix Shifting signed 32 bit value by 31 bits problem

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Date:   Sat, 6 Jul 2019 11:41:14 -0700
From:   Shobhit Kukreti <shobhitkukreti@...il.com>
To:     Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Cc:     shobhitkukreti@...il.com
Subject: [PATCH] video: radeon.h Fix Shifting signed 32 bit value by 31 bits
 problem

Fix RB2D_DC_BUSY and HORZ_AUTO_RATIO_INC defines to use "U" cast to
avoid shifting signed 32 bit values by 31 bit problem. This is not a
problem for gcc built kernel.

However, the header file being a public api, other compilers may not
handle the condition safely resulting in undefined behavior.

Signed-off-by: Shobhit Kukreti <shobhitkukreti@...il.com>
---
 include/video/radeon.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/video/radeon.h b/include/video/radeon.h
index 005eae1..cb0a5f6 100644
--- a/include/video/radeon.h
+++ b/include/video/radeon.h
@@ -531,7 +531,7 @@
 #define RB2D_DC_FLUSH_2D			   (1 << 0)
 #define RB2D_DC_FREE_2D				   (1 << 2)
 #define RB2D_DC_FLUSH_ALL			   (RB2D_DC_FLUSH_2D | RB2D_DC_FREE_2D)
-#define RB2D_DC_BUSY				   (1 << 31)
+#define RB2D_DC_BUSY				   (1U << 31)
 
 /* DSTCACHE_MODE bits constants */
 #define RB2D_DC_AUTOFLUSH_ENABLE                   (1 << 8)
@@ -672,7 +672,7 @@
 #define HORZ_STRETCH_ENABLE			   (1 << 25)
 #define HORZ_AUTO_RATIO				   (1 << 27)
 #define HORZ_FP_LOOP_STRETCH			   (0x7 << 28)
-#define HORZ_AUTO_RATIO_INC			   (1 << 31)
+#define HORZ_AUTO_RATIO_INC			   (1U << 31)
 
 
 /* FP_VERT_STRETCH bit constants */
-- 
2.7.4