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Subject[PATCH 15/16] percpu: add __percpu for sparse.
Date
From: Rusty Russell <rusty@rustcorp.com.au>

We have to make __kernel "__attribute__((address_space(0)))" so we can
cast to it.

tj: * put_cpu_var() update.

* Annotations added to dynamic allocator interface.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
include/asm-generic/percpu.h | 4 +++-
include/linux/compiler.h | 4 +++-
include/linux/percpu-defs.h | 2 +-
include/linux/percpu.h | 18 +++++++++++-------
4 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index ca6f049..fded453 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -41,7 +41,9 @@ extern unsigned long __per_cpu_offset[NR_CPUS];
* Only S390 provides its own means of moving the pointer.
*/
#ifndef SHIFT_PERCPU_PTR
-#define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset))
+/* Weird cast keeps both GCC and sparse happy. */
+#define SHIFT_PERCPU_PTR(__p, __offset) \
+ RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
#endif

/*
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 04fb513..abba804 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -5,7 +5,7 @@

#ifdef __CHECKER__
# define __user __attribute__((noderef, address_space(1)))
-# define __kernel /* default address space */
+# define __kernel __attribute__((address_space(0)))
# define __safe __attribute__((safe))
# define __force __attribute__((force))
# define __nocast __attribute__((nocast))
@@ -15,6 +15,7 @@
# define __acquire(x) __context__(x,1)
# define __release(x) __context__(x,-1)
# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
+# define __percpu __attribute__((noderef, address_space(3)))
extern void __chk_user_ptr(const volatile void __user *);
extern void __chk_io_ptr(const volatile void __iomem *);
#else
@@ -32,6 +33,7 @@ extern void __chk_io_ptr(const volatile void __iomem *);
# define __acquire(x) (void)0
# define __release(x) (void)0
# define __cond_lock(x,c) (c)
+# define __percpu
#endif

#ifdef __KERNEL__
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index ee99f6c..0fa0cb5 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -12,7 +12,7 @@
* that section.
*/
#define __PCPU_ATTRS(sec) \
- __attribute__((section(PER_CPU_BASE_SECTION sec))) \
+ __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
PER_CPU_ATTRIBUTES

#define __PCPU_DUMMY_ATTRS \
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index f965f83..2c0d31a 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -30,8 +30,12 @@
preempt_disable(); \
&__get_cpu_var(var); }))

+/*
+ * The weird & is necessary because sparse considers (void)(var) to be
+ * a direct dereference of percpu variable (var).
+ */
#define put_cpu_var(var) do { \
- (void)(var); \
+ (void)&(var); \
preempt_enable(); \
} while (0)

@@ -130,9 +134,9 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
*/
#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu)))

-extern void *__alloc_reserved_percpu(size_t size, size_t align);
-extern void *__alloc_percpu(size_t size, size_t align);
-extern void free_percpu(void *__pdata);
+extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align);
+extern void __percpu *__alloc_percpu(size_t size, size_t align);
+extern void free_percpu(void __percpu *__pdata);

#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
extern void __init setup_per_cpu_areas(void);
@@ -142,7 +146,7 @@ extern void __init setup_per_cpu_areas(void);

#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })

-static inline void *__alloc_percpu(size_t size, size_t align)
+static inline void __percpu *__alloc_percpu(size_t size, size_t align)
{
/*
* Can't easily make larger alignment work with kmalloc. WARN
@@ -153,7 +157,7 @@ static inline void *__alloc_percpu(size_t size, size_t align)
return kzalloc(size, GFP_KERNEL);
}

-static inline void free_percpu(void *p)
+static inline void free_percpu(void __percpu *p)
{
kfree(p);
}
@@ -168,7 +172,7 @@ static inline void *pcpu_lpage_remapped(void *kaddr)
#endif /* CONFIG_SMP */

#define alloc_percpu(type) \
- (typeof(type) *)__alloc_percpu(sizeof(type), __alignof__(type))
+ (typeof(type) __percpu *)__alloc_percpu(sizeof(type), __alignof__(type))

/*
* Optional methods for optimized non-lvalue per-cpu variable access.
--
1.6.4.2


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