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>

1 files changed, 22 insertions, 168 deletions

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 9ca008f0c542..32cd1f67462e 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -172,10 +172,10 @@ extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
  * 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 @@ do {									\
 
 #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 @@ do {									\
 #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 @@ do {									\
 
 #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 @@ do {									\
 #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 @@ do {									\
 #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 @@ do {									\
 #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 @@ do {									\
         __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 */