Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
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include/linux/compiler.h
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include/linux/compiler.h
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# define __section(S) __attribute__ ((__section__(#S)))
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#endif
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/*
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* Prevent the compiler from merging or refetching accesses. The compiler
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* is also forbidden from reordering successive instances of ACCESS_ONCE(),
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* but only when the compiler is aware of some particular ordering. One way
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* to make the compiler aware of ordering is to put the two invocations of
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* ACCESS_ONCE() in different C statements.
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*
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* This macro does absolutely -nothing- to prevent the CPU from reordering,
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* merging, or refetching absolutely anything at any time.
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*/
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#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
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#endif /* __LINUX_COMPILER_H */
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include/linux/rcupdate.h
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include/linux/rcupdate.h
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*/
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#define rcu_read_unlock_bh() __rcu_read_unlock_bh()
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/*
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* Prevent the compiler from merging or refetching accesses. The compiler
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* is also forbidden from reordering successive instances of ACCESS_ONCE(),
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* but only when the compiler is aware of some particular ordering. One way
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* to make the compiler aware of ordering is to put the two invocations of
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* ACCESS_ONCE() in different C statements.
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*
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* This macro does absolutely -nothing- to prevent the CPU from reordering,
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* merging, or refetching absolutely anything at any time.
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*/
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#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
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/**
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* rcu_dereference - fetch an RCU-protected pointer in an
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* RCU read-side critical section. This pointer may later