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author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-05-11 02:51:16 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-05-11 02:51:16 (GMT) |
commit | 9c3cdc1f83a6e07092392ff4aba6466517dbd1d0 (patch) | |
tree | 4dc890f607da4f85ca3a66770e4bce109879e69b /include | |
parent | 3ed43c745d2ce0c4ca15ad406285d1cc7e8ceec3 (diff) | |
download | linux-fsl-qoriq-9c3cdc1f83a6e07092392ff4aba6466517dbd1d0.tar.xz |
Move ACCESS_ONCE() to <linux/compiler.h>
It actually makes much more sense there, and we do tend to need it for
non-RCU usage too. Moving it to <linux/compiler.h> will allow some
other cases that have open-coded the same logic to use the same helper
function that RCU has used.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-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 dcae0c8..c8bd2da 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -182,4 +182,16 @@ extern void __chk_io_ptr(const volatile void __iomem *); # define __section(S) __attribute__ ((__section__(#S))) #endif +/* + * Prevent the compiler from merging or refetching accesses. The compiler + * is also forbidden from reordering successive instances of ACCESS_ONCE(), + * but only when the compiler is aware of some particular ordering. One way + * to make the compiler aware of ordering is to put the two invocations of + * ACCESS_ONCE() in different C statements. + * + * This macro does absolutely -nothing- to prevent the CPU from reordering, + * merging, or refetching absolutely anything at any time. + */ +#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) + #endif /* __LINUX_COMPILER_H */ diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 8082d65..d42dbec 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -131,18 +131,6 @@ struct rcu_head { */ #define rcu_read_unlock_bh() __rcu_read_unlock_bh() -/* - * Prevent the compiler from merging or refetching accesses. The compiler - * is also forbidden from reordering successive instances of ACCESS_ONCE(), - * but only when the compiler is aware of some particular ordering. One way - * to make the compiler aware of ordering is to put the two invocations of - * ACCESS_ONCE() in different C statements. - * - * This macro does absolutely -nothing- to prevent the CPU from reordering, - * merging, or refetching absolutely anything at any time. - */ -#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) - /** * rcu_dereference - fetch an RCU-protected pointer in an * RCU read-side critical section. This pointer may later |