diff options
Diffstat (limited to 'include/linux')
-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 |