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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 4/8] asm/atomic.h: common prototyping (add xen/atomic.h)
Create a common-side <xen/atomic.h> to establish, among others, prototypes of
atomic functions called from common-code. Done to avoid introducing
inconsistencies between arch-side <asm/atomic.h> headers when we make subtle
changes to one of them.
Some arm-side macros had to be turned into inline functions in the process.
Removed outdated comment ("NB. I've [...]").
Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
Changed since v2:
* sample code for atomic_cmpxchg() (doc-comment in <xen/atomic.h>) updated to
use atomic_read() instead of directly accessing v.counter
---
xen/include/asm-arm/atomic.h | 45 ++++++++----
xen/include/asm-x86/atomic.h | 103 +-------------------------
xen/include/xen/atomic.h | 171 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 202 insertions(+), 117 deletions(-)
create mode 100644 xen/include/xen/atomic.h
diff --git a/xen/include/asm-arm/atomic.h b/xen/include/asm-arm/atomic.h
index 620c636..a79420a 100644
--- a/xen/include/asm-arm/atomic.h
+++ b/xen/include/asm-arm/atomic.h
@@ -2,6 +2,7 @@
#define __ARCH_ARM_ATOMIC__
#include <xen/config.h>
+#include <xen/atomic.h>
#include <xen/prefetch.h>
#include <asm/system.h>
@@ -95,15 +96,6 @@ void __bad_atomic_size(void);
default: __bad_atomic_size(); break; \
} \
})
-
-/*
- * NB. I've pushed the volatile qualifier into the operations. This allows
- * fast accessors such as _atomic_read() and _atomic_set() which don't give
- * the compiler a fit.
- */
-typedef struct { int counter; } atomic_t;
-
-#define ATOMIC_INIT(i) { (i) }
/*
* On ARM, ordinary assignment (str instruction) doesn't clear the local
@@ -141,12 +133,35 @@ static inline void _atomic_set(atomic_t *v, int i)
#define atomic_inc_return(v) (atomic_add_return(1, v))
#define atomic_dec_return(v) (atomic_sub_return(1, v))
-#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
-#define atomic_inc(v) atomic_add(1, v)
-#define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
-#define atomic_dec(v) atomic_sub(1, v)
-#define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
-#define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0)
+static inline int atomic_sub_and_test(int i, atomic_t *v)
+{
+ return atomic_sub_return(i, v) == 0;
+}
+
+static inline void atomic_inc(atomic_t *v)
+{
+ atomic_add(1, v);
+}
+
+static inline int atomic_inc_and_test(atomic_t *v)
+{
+ return atomic_add_return(1, v) == 0;
+}
+
+static inline void atomic_dec(atomic_t *v)
+{
+ atomic_sub(1, v);
+}
+
+static inline int atomic_dec_and_test(atomic_t *v)
+{
+ return atomic_sub_return(1, v) == 0;
+}
+
+static inline int atomic_add_negative(int i, atomic_t *v)
+{
+ return atomic_add_return(i, v) < 0;
+}
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
diff --git a/xen/include/asm-x86/atomic.h b/xen/include/asm-x86/atomic.h
index 5f9f2dd..3e99b03 100644
--- a/xen/include/asm-x86/atomic.h
+++ b/xen/include/asm-x86/atomic.h
@@ -2,6 +2,7 @@
#define __ARCH_X86_ATOMIC__
#include <xen/config.h>
+#include <xen/atomic.h>
#include <asm/system.h>
#define build_read_atomic(name, size, type, reg, barrier) \
@@ -79,56 +80,21 @@ void __bad_atomic_size(void);
} \
})
-/*
- * NB. I've pushed the volatile qualifier into the operations. This allows
- * fast accessors such as _atomic_read() and _atomic_set() which don't give
- * the compiler a fit.
- */
-typedef struct { int counter; } atomic_t;
-
-#define ATOMIC_INIT(i) { (i) }
-
-/**
- * atomic_read - read atomic variable
- * @v: pointer of type atomic_t
- *
- * Atomically reads the value of @v.
- */
static inline int atomic_read(atomic_t *v)
{
return read_atomic(&v->counter);
}
-/**
- * _atomic_read - read atomic variable non-atomically
- * @v atomic_t
- *
- * Non-atomically reads the value of @v
- */
static inline int _atomic_read(atomic_t v)
{
return v.counter;
}
-/**
- * atomic_set - set atomic variable
- * @v: pointer of type atomic_t
- * @i: required value
- *
- * Atomically sets the value of @v to @i.
- */
static inline void atomic_set(atomic_t *v, int i)
{
write_atomic(&v->counter, i);
}
-/**
- * _atomic_set - set atomic variable non-atomically
- * @v: pointer of type atomic_t
- * @i: required value
- *
- * Non-atomically sets the value of @v to @i.
- */
static inline void _atomic_set(atomic_t *v, int i)
{
v->counter = i;
@@ -139,13 +105,6 @@ static inline int atomic_cmpxchg(atomic_t *v, int old, int
new)
return cmpxchg(&v->counter, old, new);
}
-/**
- * atomic_add - add integer to atomic variable
- * @i: integer value to add
- * @v: pointer of type atomic_t
- *
- * Atomically adds @i to @v.
- */
static inline void atomic_add(int i, atomic_t *v)
{
asm volatile (
@@ -154,25 +113,11 @@ static inline void atomic_add(int i, atomic_t *v)
: "ir" (i), "m" (*(volatile int *)&v->counter) );
}
-/**
- * atomic_add_return - add integer and return
- * @i: integer value to add
- * @v: pointer of type atomic_t
- *
- * Atomically adds @i to @v and returns @i + @v
- */
static inline int atomic_add_return(int i, atomic_t *v)
{
return i + arch_fetch_and_add(&v->counter, i);
}
-/**
- * atomic_sub - subtract the atomic variable
- * @i: integer value to subtract
- * @v: pointer of type atomic_t
- *
- * Atomically subtracts @i from @v.
- */
static inline void atomic_sub(int i, atomic_t *v)
{
asm volatile (
@@ -181,15 +126,6 @@ static inline void atomic_sub(int i, atomic_t *v)
: "ir" (i), "m" (*(volatile int *)&v->counter) );
}
-/**
- * atomic_sub_and_test - subtract value from variable and test result
- * @i: integer value to subtract
- * @v: pointer of type atomic_t
- *
- * Atomically subtracts @i from @v and returns
- * true if the result is zero, or false for all
- * other cases.
- */
static inline int atomic_sub_and_test(int i, atomic_t *v)
{
unsigned char c;
@@ -201,12 +137,6 @@ static inline int atomic_sub_and_test(int i, atomic_t *v)
return c;
}
-/**
- * atomic_inc - increment atomic variable
- * @v: pointer of type atomic_t
- *
- * Atomically increments @v by 1.
- */
static inline void atomic_inc(atomic_t *v)
{
asm volatile (
@@ -215,14 +145,6 @@ static inline void atomic_inc(atomic_t *v)
: "m" (*(volatile int *)&v->counter) );
}
-/**
- * atomic_inc_and_test - increment and test
- * @v: pointer of type atomic_t
- *
- * Atomically increments @v by 1
- * and returns true if the result is zero, or false for all
- * other cases.
- */
static inline int atomic_inc_and_test(atomic_t *v)
{
unsigned char c;
@@ -234,12 +156,6 @@ static inline int atomic_inc_and_test(atomic_t *v)
return c != 0;
}
-/**
- * atomic_dec - decrement atomic variable
- * @v: pointer of type atomic_t
- *
- * Atomically decrements @v by 1.
- */
static inline void atomic_dec(atomic_t *v)
{
asm volatile (
@@ -248,14 +164,6 @@ static inline void atomic_dec(atomic_t *v)
: "m" (*(volatile int *)&v->counter) );
}
-/**
- * atomic_dec_and_test - decrement and test
- * @v: pointer of type atomic_t
- *
- * Atomically decrements @v by 1 and
- * returns true if the result is 0, or false for all other
- * cases.
- */
static inline int atomic_dec_and_test(atomic_t *v)
{
unsigned char c;
@@ -267,15 +175,6 @@ static inline int atomic_dec_and_test(atomic_t *v)
return c != 0;
}
-/**
- * atomic_add_negative - add and test if negative
- * @v: pointer of type atomic_t
- * @i: integer value to add
- *
- * Atomically adds @i to @v and returns true
- * if the result is negative, or false when
- * result is greater than or equal to zero.
- */
static inline int atomic_add_negative(int i, atomic_t *v)
{
unsigned char c;
diff --git a/xen/include/xen/atomic.h b/xen/include/xen/atomic.h
new file mode 100644
index 0000000..d072912
--- /dev/null
+++ b/xen/include/xen/atomic.h
@@ -0,0 +1,171 @@
+/*
+ * include/xen/atomic.h
+ *
+ * Common atomic operations entities (atomic_t, function prototypes).
+ * Include _from_ arch-side <asm/atomic.h>.
+ *
+ * Copyright (c) 2016 Bitdefender S.R.L.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __XEN_ATOMIC_H__
+#define __XEN_ATOMIC_H__
+
+typedef struct { int counter; } atomic_t;
+
+#define ATOMIC_INIT(i) { (i) }
+
+/**
+ * atomic_read - read atomic variable
+ * @v: pointer of type atomic_t
+ *
+ * Atomically reads the value of @v.
+ */
+static inline int atomic_read(atomic_t *v);
+
+/**
+ * _atomic_read - read atomic variable non-atomically
+ * @v atomic_t
+ *
+ * Non-atomically reads the value of @v
+ */
+static inline int _atomic_read(atomic_t v);
+
+/**
+ * atomic_set - set atomic variable
+ * @v: pointer of type atomic_t
+ * @i: required value
+ *
+ * Atomically sets the value of @v to @i.
+ */
+static inline void atomic_set(atomic_t *v, int i);
+
+/**
+ * _atomic_set - set atomic variable non-atomically
+ * @v: pointer of type atomic_t
+ * @i: required value
+ *
+ * Non-atomically sets the value of @v to @i.
+ */
+static inline void _atomic_set(atomic_t *v, int i);
+
+/**
+ * atomic_cmpxchg - compare and exchange an atomic variable
+ * @v: pointer of type atomic_t
+ * @old: old value
+ * @new: new value
+ *
+ * Before calling, @old should be set to @v.
+ * Succeeds if @old == @v (likely), in which case stores @new in @v.
+ * Returns the initial value in @v, hence succeeds when the return value
+ * matches that of @old.
+ *
+ * Sample (tries atomic increment of v until the operation succeeds):
+ *
+ * while(1)
+ * {
+ * int old = atomic_read(&v);
+ * int new = old + 1;
+ * if ( likely(old == atomic_cmpxchg(&v, old, new)) )
+ * break; // success!
+ * }
+ */
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new);
+
+/**
+ * atomic_add - add integer to atomic variable
+ * @i: integer value to add
+ * @v: pointer of type atomic_t
+ *
+ * Atomically adds @i to @v.
+ */
+static inline void atomic_add(int i, atomic_t *v);
+
+/**
+ * atomic_add_return - add integer and return
+ * @i: integer value to add
+ * @v: pointer of type atomic_t
+ *
+ * Atomically adds @i to @v and returns @i + @v
+ */
+static inline int atomic_add_return(int i, atomic_t *v);
+
+/**
+ * atomic_sub - subtract the atomic variable
+ * @i: integer value to subtract
+ * @v: pointer of type atomic_t
+ *
+ * Atomically subtracts @i from @v.
+ */
+static inline void atomic_sub(int i, atomic_t *v);
+
+/**
+ * atomic_sub_and_test - subtract value from variable and test result
+ * @i: integer value to subtract
+ * @v: pointer of type atomic_t
+ *
+ * Atomically subtracts @i from @v and returns
+ * true if the result is zero, or false for all
+ * other cases.
+ */
+static inline int atomic_sub_and_test(int i, atomic_t *v);
+
+/**
+ * atomic_inc - increment atomic variable
+ * @v: pointer of type atomic_t
+ *
+ * Atomically increments @v by 1.
+ */
+static inline void atomic_inc(atomic_t *v);
+
+/**
+ * atomic_inc_and_test - increment and test
+ * @v: pointer of type atomic_t
+ *
+ * Atomically increments @v by 1
+ * and returns true if the result is zero, or false for all
+ * other cases.
+ */
+static inline int atomic_inc_and_test(atomic_t *v);
+
+/**
+ * atomic_dec - decrement atomic variable
+ * @v: pointer of type atomic_t
+ *
+ * Atomically decrements @v by 1.
+ */
+static inline void atomic_dec(atomic_t *v);
+
+/**
+ * atomic_dec_and_test - decrement and test
+ * @v: pointer of type atomic_t
+ *
+ * Atomically decrements @v by 1 and
+ * returns true if the result is 0, or false for all other
+ * cases.
+ */
+static inline int atomic_dec_and_test(atomic_t *v);
+
+/**
+ * atomic_add_negative - add and test if negative
+ * @v: pointer of type atomic_t
+ * @i: integer value to add
+ *
+ * Atomically adds @i to @v and returns true
+ * if the result is negative, or false when
+ * result is greater than or equal to zero.
+ */
+static inline int atomic_add_negative(int i, atomic_t *v);
+
+#endif /* __XEN_ATOMIC_H__ */
--
2.5.0
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