From: Johannes Berg <johannes.berg@xxxxxxxxx>
Subject: min/max: remove sparse warnings when they're nested
Currently, when min/max are nested within themselves, sparse will warn:
warning: symbol '_min1' shadows an earlier one
originally declared here
warning: symbol '_min1' shadows an earlier one
originally declared here
warning: symbol '_min2' shadows an earlier one
originally declared here
This also immediately happens when min3() or max3() are used.
Since sparse implements __COUNTER__, we can use __UNIQUE_ID() to generate
unique variable names, avoiding this.
Link: http://lkml.kernel.org/r/1471519773-29882-1-git-send-email-johannes@xxxxxxxxxxxxxxxx
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kernel.h | 48 ++++++++++++++++++++++-----------------
1 file changed, 28 insertions(+), 20 deletions(-)
diff -puN include/linux/kernel.h~min-max-remove-sparse-warnings-when-theyre-nested include/linux/kernel.h
--- a/include/linux/kernel.h~min-max-remove-sparse-warnings-when-theyre-nested
+++ a/include/linux/kernel.h
@@ -733,17 +733,25 @@ static inline void ftrace_dump(enum ftra
* strict type-checking.. See the
* "unnecessary" pointer comparison.
*/
-#define min(x, y) ({ \
- typeof(x) _min1 = (x); \
- typeof(y) _min2 = (y); \
- (void) (&_min1 == &_min2); \
- _min1 < _min2 ? _min1 : _min2; })
-
-#define max(x, y) ({ \
- typeof(x) _max1 = (x); \
- typeof(y) _max2 = (y); \
- (void) (&_max1 == &_max2); \
- _max1 > _max2 ? _max1 : _max2; })
+#define __min(t1, t2, min1, min2, x, y) ({ \
+ t1 min1 = (x); \
+ t2 min2 = (y); \
+ (void) (&min1 == &min2); \
+ min1 < min2 ? min1 : min2; })
+#define min(x, y) \
+ __min(typeof(x), typeof(y), \
+ __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \
+ x, y)
+
+#define __max(t1, t2, max1, max2, x, y) ({ \
+ t1 max1 = (x); \
+ t2 max2 = (y); \
+ (void) (&max1 == &max2); \
+ max1 > max2 ? max1 : max2; })
+#define max(x, y) \
+ __max(typeof(x), typeof(y), \
+ __UNIQUE_ID(max1_), __UNIQUE_ID(max2_), \
+ x, y)
#define min3(x, y, z) min((typeof(x))min(x, y), z)
#define max3(x, y, z) max((typeof(x))max(x, y), z)
@@ -775,15 +783,15 @@ static inline void ftrace_dump(enum ftra
*
* Or not use min/max/clamp at all, of course.
*/
-#define min_t(type, x, y) ({ \
- type __min1 = (x); \
- type __min2 = (y); \
- __min1 < __min2 ? __min1: __min2; })
-
-#define max_t(type, x, y) ({ \
- type __max1 = (x); \
- type __max2 = (y); \
- __max1 > __max2 ? __max1: __max2; })
+#define min_t(type, x, y) \
+ __min(type, type, \
+ __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \
+ x, y)
+
+#define max_t(type, x, y) \
+ __max(type, type, \
+ __UNIQUE_ID(min1_), __UNIQUE_ID(min2_), \
+ x, y)
/**
* clamp_t - return a value clamped to a given range using a given type
_
--
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