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authorDavid S. Miller <davem@davemloft.net>2008-05-15 03:34:44 -0400
committerDavid S. Miller <davem@davemloft.net>2008-05-15 03:34:44 -0400
commit63fe46da9c380b3f2bbdf3765044649517cc717c (patch)
tree9478c1aca1d692b408955aea20c9cd9a37e589c0 /include/linux/compiler.h
parent99dd1a2b8347ac2ae802300b7862f6f7bcf17139 (diff)
parent066b2118976e6e7cc50eed39e2747c75343a23c4 (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.h12
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 *);
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 */