diff options
| -rw-r--r-- | include/linux/compiler.h | 12 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 12 |
2 files changed, 12 insertions, 12 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index dcae0c8d97e6..c8bd2daf95ec 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h | |||
| @@ -182,4 +182,16 @@ extern void __chk_io_ptr(const volatile void __iomem *); | |||
| 182 | # define __section(S) __attribute__ ((__section__(#S))) | 182 | # define __section(S) __attribute__ ((__section__(#S))) |
| 183 | #endif | 183 | #endif |
| 184 | 184 | ||
| 185 | /* | ||
| 186 | * Prevent the compiler from merging or refetching accesses. The compiler | ||
| 187 | * is also forbidden from reordering successive instances of ACCESS_ONCE(), | ||
| 188 | * but only when the compiler is aware of some particular ordering. One way | ||
| 189 | * to make the compiler aware of ordering is to put the two invocations of | ||
| 190 | * ACCESS_ONCE() in different C statements. | ||
| 191 | * | ||
| 192 | * This macro does absolutely -nothing- to prevent the CPU from reordering, | ||
| 193 | * merging, or refetching absolutely anything at any time. | ||
| 194 | */ | ||
| 195 | #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) | ||
| 196 | |||
| 185 | #endif /* __LINUX_COMPILER_H */ | 197 | #endif /* __LINUX_COMPILER_H */ |
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 8082d6587a0f..d42dbec06083 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h | |||
| @@ -131,18 +131,6 @@ struct rcu_head { | |||
| 131 | */ | 131 | */ |
| 132 | #define rcu_read_unlock_bh() __rcu_read_unlock_bh() | 132 | #define rcu_read_unlock_bh() __rcu_read_unlock_bh() |
| 133 | 133 | ||
| 134 | /* | ||
| 135 | * Prevent the compiler from merging or refetching accesses. The compiler | ||
| 136 | * is also forbidden from reordering successive instances of ACCESS_ONCE(), | ||
| 137 | * but only when the compiler is aware of some particular ordering. One way | ||
| 138 | * to make the compiler aware of ordering is to put the two invocations of | ||
| 139 | * ACCESS_ONCE() in different C statements. | ||
| 140 | * | ||
| 141 | * This macro does absolutely -nothing- to prevent the CPU from reordering, | ||
| 142 | * merging, or refetching absolutely anything at any time. | ||
| 143 | */ | ||
| 144 | #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) | ||
| 145 | |||
| 146 | /** | 134 | /** |
| 147 | * rcu_dereference - fetch an RCU-protected pointer in an | 135 | * rcu_dereference - fetch an RCU-protected pointer in an |
| 148 | * RCU read-side critical section. This pointer may later | 136 | * RCU read-side critical section. This pointer may later |
