Cheatsheet

Literal include of tools/memory-model/Documentation/cheatsheet.txt.

---

                                  Prior Operation     Subsequent Operation
                                  ---------------  ---------------------------
                               C  Self  R  W  RMW  Self  R  W  DR  DW  RMW  SV
                              --  ----  -  -  ---  ----  -  -  --  --  ---  --

Relaxed store                        Y                                       Y
Relaxed load                         Y                          Y   Y        Y
Relaxed RMW operation                Y                          Y   Y        Y
rcu_dereference()                    Y                          Y   Y        Y
Successful *_acquire()               R                   Y  Y   Y   Y    Y   Y
Successful *_release()         C        Y  Y    Y     W                      Y
smp_rmb()                               Y       R        Y      Y        R
smp_wmb()                                  Y    W           Y       Y    W
smp_mb() & synchronize_rcu()  CP        Y  Y    Y        Y  Y   Y   Y    Y
Successful full non-void RMW  CP     Y  Y  Y    Y     Y  Y  Y   Y   Y    Y   Y
smp_mb__before_atomic()       CP        Y  Y    Y        a  a   a   a    Y
smp_mb__after_atomic()        CP        a  a    Y        Y  Y   Y   Y    Y


Key:    Relaxed:  A relaxed operation is either READ_ONCE(), WRITE_ONCE(),
                  a *_relaxed() RMW operation, an unsuccessful RMW
                  operation, a non-value-returning RMW operation such
                  as atomic_inc(), or one of the atomic*_read() and
                  atomic*_set() family of operations.
        C:        Ordering is cumulative
        P:        Ordering propagates
        R:        Read, for example, READ_ONCE(), or read portion of RMW
        W:        Write, for example, WRITE_ONCE(), or write portion of RMW
        Y:        Provides ordering
        a:        Provides ordering given intervening RMW atomic operation
        DR:       Dependent read (address dependency)
        DW:       Dependent write (address, data, or control dependency)
        RMW:      Atomic read-modify-write operation
        SELF:     Orders self, as opposed to accesses before and/or after
        SV:       Orders later accesses to the same variable