percpu: Remove irqsafe_cpu_xxx variants
We simply say that regular this_cpu use must be safe regardless of
preemption and interrupt state. That has no material change for x86
and s390 implementations of this_cpu operations. However, arches that
do not provide their own implementation for this_cpu operations will
now get code generated that disables interrupts instead of preemption.
-tj: This is part of on-going percpu API cleanup. For detailed
discussion of the subject, please refer to the following thread.
http://thread.gmane.org/gmane.linux.kernel/1222078
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
LKML-Reference: <alpine.DEB.2.00.1112221154380.11787@router.home>
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 9ca008f..32cd1f6 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -172,10 +172,10 @@
* equal char, int or long. percpu_read() evaluates to a lvalue and
* all others to void.
*
- * These operations are guaranteed to be atomic w.r.t. preemption.
- * The generic versions use plain get/put_cpu_var(). Archs are
+ * These operations are guaranteed to be atomic.
+ * The generic versions disable interrupts. Archs are
* encouraged to implement single-instruction alternatives which don't
- * require preemption protection.
+ * require protection.
*/
#ifndef percpu_read
# define percpu_read(var) \
@@ -347,9 +347,10 @@
#define _this_cpu_generic_to_op(pcp, val, op) \
do { \
- preempt_disable(); \
+ unsigned long flags; \
+ local_irq_save(flags); \
*__this_cpu_ptr(&(pcp)) op val; \
- preempt_enable(); \
+ local_irq_restore(flags); \
} while (0)
#ifndef this_cpu_write
@@ -447,10 +448,11 @@
#define _this_cpu_generic_add_return(pcp, val) \
({ \
typeof(pcp) ret__; \
- preempt_disable(); \
+ unsigned long flags; \
+ local_irq_save(flags); \
__this_cpu_add(pcp, val); \
ret__ = __this_cpu_read(pcp); \
- preempt_enable(); \
+ local_irq_restore(flags); \
ret__; \
})
@@ -476,10 +478,11 @@
#define _this_cpu_generic_xchg(pcp, nval) \
({ typeof(pcp) ret__; \
- preempt_disable(); \
+ unsigned long flags; \
+ local_irq_save(flags); \
ret__ = __this_cpu_read(pcp); \
__this_cpu_write(pcp, nval); \
- preempt_enable(); \
+ local_irq_restore(flags); \
ret__; \
})
@@ -501,12 +504,14 @@
#endif
#define _this_cpu_generic_cmpxchg(pcp, oval, nval) \
-({ typeof(pcp) ret__; \
- preempt_disable(); \
+({ \
+ typeof(pcp) ret__; \
+ unsigned long flags; \
+ local_irq_save(flags); \
ret__ = __this_cpu_read(pcp); \
if (ret__ == (oval)) \
__this_cpu_write(pcp, nval); \
- preempt_enable(); \
+ local_irq_restore(flags); \
ret__; \
})
@@ -538,10 +543,11 @@
#define _this_cpu_generic_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
({ \
int ret__; \
- preempt_disable(); \
+ unsigned long flags; \
+ local_irq_save(flags); \
ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \
oval1, oval2, nval1, nval2); \
- preempt_enable(); \
+ local_irq_restore(flags); \
ret__; \
})
@@ -567,9 +573,9 @@
#endif
/*
- * Generic percpu operations that do not require preemption handling.
+ * Generic percpu operations for context that are safe from preemption/interrupts.
* Either we do not care about races or the caller has the
- * responsibility of handling preemptions issues. Arch code can still
+ * responsibility of handling preemption/interrupt issues. Arch code can still
* override these instructions since the arch per cpu code may be more
* efficient and may actually get race freeness for free (that is the
* case for x86 for example).
@@ -802,156 +808,4 @@
__pcpu_double_call_return_bool(__this_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
#endif
-/*
- * IRQ safe versions of the per cpu RMW operations. Note that these operations
- * are *not* safe against modification of the same variable from another
- * processors (which one gets when using regular atomic operations)
- * They are guaranteed to be atomic vs. local interrupts and
- * preemption only.
- */
-#define irqsafe_cpu_generic_to_op(pcp, val, op) \
-do { \
- unsigned long flags; \
- local_irq_save(flags); \
- *__this_cpu_ptr(&(pcp)) op val; \
- local_irq_restore(flags); \
-} while (0)
-
-#ifndef irqsafe_cpu_add
-# ifndef irqsafe_cpu_add_1
-# define irqsafe_cpu_add_1(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), +=)
-# endif
-# ifndef irqsafe_cpu_add_2
-# define irqsafe_cpu_add_2(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), +=)
-# endif
-# ifndef irqsafe_cpu_add_4
-# define irqsafe_cpu_add_4(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), +=)
-# endif
-# ifndef irqsafe_cpu_add_8
-# define irqsafe_cpu_add_8(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), +=)
-# endif
-# define irqsafe_cpu_add(pcp, val) __pcpu_size_call(irqsafe_cpu_add_, (pcp), (val))
-#endif
-
-#ifndef irqsafe_cpu_sub
-# define irqsafe_cpu_sub(pcp, val) irqsafe_cpu_add((pcp), -(val))
-#endif
-
-#ifndef irqsafe_cpu_inc
-# define irqsafe_cpu_inc(pcp) irqsafe_cpu_add((pcp), 1)
-#endif
-
-#ifndef irqsafe_cpu_dec
-# define irqsafe_cpu_dec(pcp) irqsafe_cpu_sub((pcp), 1)
-#endif
-
-#ifndef irqsafe_cpu_and
-# ifndef irqsafe_cpu_and_1
-# define irqsafe_cpu_and_1(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), &=)
-# endif
-# ifndef irqsafe_cpu_and_2
-# define irqsafe_cpu_and_2(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), &=)
-# endif
-# ifndef irqsafe_cpu_and_4
-# define irqsafe_cpu_and_4(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), &=)
-# endif
-# ifndef irqsafe_cpu_and_8
-# define irqsafe_cpu_and_8(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), &=)
-# endif
-# define irqsafe_cpu_and(pcp, val) __pcpu_size_call(irqsafe_cpu_and_, (val))
-#endif
-
-#ifndef irqsafe_cpu_or
-# ifndef irqsafe_cpu_or_1
-# define irqsafe_cpu_or_1(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), |=)
-# endif
-# ifndef irqsafe_cpu_or_2
-# define irqsafe_cpu_or_2(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), |=)
-# endif
-# ifndef irqsafe_cpu_or_4
-# define irqsafe_cpu_or_4(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), |=)
-# endif
-# ifndef irqsafe_cpu_or_8
-# define irqsafe_cpu_or_8(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), |=)
-# endif
-# define irqsafe_cpu_or(pcp, val) __pcpu_size_call(irqsafe_cpu_or_, (val))
-#endif
-
-#ifndef irqsafe_cpu_xor
-# ifndef irqsafe_cpu_xor_1
-# define irqsafe_cpu_xor_1(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), ^=)
-# endif
-# ifndef irqsafe_cpu_xor_2
-# define irqsafe_cpu_xor_2(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), ^=)
-# endif
-# ifndef irqsafe_cpu_xor_4
-# define irqsafe_cpu_xor_4(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), ^=)
-# endif
-# ifndef irqsafe_cpu_xor_8
-# define irqsafe_cpu_xor_8(pcp, val) irqsafe_cpu_generic_to_op((pcp), (val), ^=)
-# endif
-# define irqsafe_cpu_xor(pcp, val) __pcpu_size_call(irqsafe_cpu_xor_, (val))
-#endif
-
-#define irqsafe_cpu_generic_cmpxchg(pcp, oval, nval) \
-({ \
- typeof(pcp) ret__; \
- unsigned long flags; \
- local_irq_save(flags); \
- ret__ = __this_cpu_read(pcp); \
- if (ret__ == (oval)) \
- __this_cpu_write(pcp, nval); \
- local_irq_restore(flags); \
- ret__; \
-})
-
-#ifndef irqsafe_cpu_cmpxchg
-# ifndef irqsafe_cpu_cmpxchg_1
-# define irqsafe_cpu_cmpxchg_1(pcp, oval, nval) irqsafe_cpu_generic_cmpxchg(pcp, oval, nval)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_2
-# define irqsafe_cpu_cmpxchg_2(pcp, oval, nval) irqsafe_cpu_generic_cmpxchg(pcp, oval, nval)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_4
-# define irqsafe_cpu_cmpxchg_4(pcp, oval, nval) irqsafe_cpu_generic_cmpxchg(pcp, oval, nval)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_8
-# define irqsafe_cpu_cmpxchg_8(pcp, oval, nval) irqsafe_cpu_generic_cmpxchg(pcp, oval, nval)
-# endif
-# define irqsafe_cpu_cmpxchg(pcp, oval, nval) \
- __pcpu_size_call_return2(irqsafe_cpu_cmpxchg_, (pcp), oval, nval)
-#endif
-
-#define irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
-({ \
- int ret__; \
- unsigned long flags; \
- local_irq_save(flags); \
- ret__ = __this_cpu_generic_cmpxchg_double(pcp1, pcp2, \
- oval1, oval2, nval1, nval2); \
- local_irq_restore(flags); \
- ret__; \
-})
-
-#ifndef irqsafe_cpu_cmpxchg_double
-# ifndef irqsafe_cpu_cmpxchg_double_1
-# define irqsafe_cpu_cmpxchg_double_1(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_double_2
-# define irqsafe_cpu_cmpxchg_double_2(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_double_4
-# define irqsafe_cpu_cmpxchg_double_4(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
-# endif
-# ifndef irqsafe_cpu_cmpxchg_double_8
-# define irqsafe_cpu_cmpxchg_double_8(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- irqsafe_generic_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2)
-# endif
-# define irqsafe_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
- __pcpu_double_call_return_bool(irqsafe_cpu_cmpxchg_double_, (pcp1), (pcp2), (oval1), (oval2), (nval1), (nval2))
-#endif
-
#endif /* __LINUX_PERCPU_H */