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| author | David S. Miller <davem@davemloft.net> | 2008-05-15 00:34:44 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2008-05-15 00:34:44 -0700 |
| commit | 63fe46da9c380b3f2bbdf3765044649517cc717c (patch) | |
| tree | 9478c1aca1d692b408955aea20c9cd9a37e589c0 /include/linux/compiler.h | |
| parent | 99dd1a2b8347ac2ae802300b7862f6f7bcf17139 (diff) | |
| parent | 066b2118976e6e7cc50eed39e2747c75343a23c4 (diff) | |
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts:
drivers/net/wireless/iwlwifi/iwl-4965-rs.c
drivers/net/wireless/rt2x00/rt61pci.c
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 12 |
1 files changed, 12 insertions, 0 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 *); # 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 */ |