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2 commits

Author SHA1 Message Date
Will Deacon
61e02392d3 locking/atomic/bitops: Document and clarify ordering semantics for failed test_and_{}_bit()
A test_and_{}_bit() operation fails if the value of the bit is such that
the modification does not take place. For example, if test_and_set_bit()
returns 1. In these cases, follow the behaviour of cmpxchg and allow the
operation to be unordered. This also applies to test_and_set_bit_lock()
if the lock is found to be be taken already.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1518528619-20049-1-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-13 14:55:53 +01:00
Peter Zijlstra
706eeb3e9c Documentation/locking/atomic: Add documents for new atomic_t APIs
Since we've vastly expanded the atomic_t interface in recent years the
existing documentation is woefully out of date and people seem to get
confused a bit.

Start a new document to hopefully better explain the current state of
affairs.

The old atomic_ops.txt also covers bitmaps and a few more details so
this is not a full replacement and we'll therefore keep that document
around until such a time that we've managed to write more text to cover
its entire.

Also please, ReST people, go away.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-10 12:29:00 +02:00