summaryrefslogtreecommitdiff
path: root/include/linux/kernel.h
diff options
context:
space:
mode:
authorIngo Molnar <mingo@kernel.org>2014-02-02 09:45:39 +0100
committerIngo Molnar <mingo@kernel.org>2014-02-02 09:45:39 +0100
commiteaa4e4fcf1b5c60e656d93242f7fe422173f25b2 (patch)
treec05d5d6ca3f625d72a9d136b4c485d3dc9472089 /include/linux/kernel.h
parentbe1e4e760d940c14d119bffef5eb007dfdf29046 (diff)
parent5cb480f6b488128140c940abff3c36f524a334a8 (diff)
Merge branch 'linus' into sched/core, to resolve conflicts
Conflicts: kernel/sysctl.c Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/kernel.h')
-rw-r--r--include/linux/kernel.h32
1 files changed, 32 insertions, 0 deletions
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 2aa3d4b000e6..196d1ea86df0 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -29,6 +29,19 @@
#define ULLONG_MAX (~0ULL)
#define SIZE_MAX (~(size_t)0)
+#define U8_MAX ((u8)~0U)
+#define S8_MAX ((s8)(U8_MAX>>1))
+#define S8_MIN ((s8)(-S8_MAX - 1))
+#define U16_MAX ((u16)~0U)
+#define S16_MAX ((s16)(U16_MAX>>1))
+#define S16_MIN ((s16)(-S16_MAX - 1))
+#define U32_MAX ((u32)~0U)
+#define S32_MAX ((s32)(U32_MAX>>1))
+#define S32_MIN ((s32)(-S32_MAX - 1))
+#define U64_MAX ((u64)~0ULL)
+#define S64_MAX ((s64)(U64_MAX>>1))
+#define S64_MIN ((s64)(-S64_MAX - 1))
+
#define STACK_MAGIC 0xdeadbeef
#define REPEAT_BYTE(x) ((~0ul / 0xff) * (x))
@@ -193,6 +206,25 @@ extern int _cond_resched(void);
(__x < 0) ? -__x : __x; \
})
+/**
+ * reciprocal_scale - "scale" a value into range [0, ep_ro)
+ * @val: value
+ * @ep_ro: right open interval endpoint
+ *
+ * Perform a "reciprocal multiplication" in order to "scale" a value into
+ * range [0, ep_ro), where the upper interval endpoint is right-open.
+ * This is useful, e.g. for accessing a index of an array containing
+ * ep_ro elements, for example. Think of it as sort of modulus, only that
+ * the result isn't that of modulo. ;) Note that if initial input is a
+ * small value, then result will return 0.
+ *
+ * Return: a result based on val in interval [0, ep_ro).
+ */
+static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
+{
+ return (u32)(((u64) val * ep_ro) >> 32);
+}
+
#if defined(CONFIG_MMU) && \
(defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
void might_fault(void);