This directory contains the following litmus tests: CoRR+poonceonce+Once.litmus Test of read-read coherence, that is, whether or not two successive reads from the same variable are ordered. CoRW+poonceonce+Once.litmus Test of read-write coherence, that is, whether or not a read from a given variable followed by a write to that same variable are ordered. CoWR+poonceonce+Once.litmus Test of write-read coherence, that is, whether or not a write to a given variable followed by a read from that same variable are ordered. CoWW+poonceonce.litmus Test of write-write coherence, that is, whether or not two successive writes to the same variable are ordered. IRIW+fencembonceonces+OnceOnce.litmus Test of independent reads from independent writes with smp_mb() between each pairs of reads. In other words, is smp_mb() sufficient to cause two different reading processes to agree on the order of a pair of writes, where each write is to a different variable by a different process? This litmus test is forbidden by LKMM's propagation rule. IRIW+poonceonces+OnceOnce.litmus Test of independent reads from independent writes with nothing between each pairs of reads. In other words, is anything at all needed to cause two different reading processes to agree on the order of a pair of writes, where each write is to a different variable by a different process? ISA2+pooncelock+pooncelock+pombonce.litmus Tests whether the ordering provided by a lock-protected S litmus test is visible to an external process whose accesses are separated by smp_mb(). This addition of an external process to S is otherwise known as ISA2. ISA2+poonceonces.litmus As below, but with store-release replaced with WRITE_ONCE() and load-acquire replaced with READ_ONCE(). ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus Can a release-acquire chain order a prior store against a later load? LB+fencembonceonce+ctrlonceonce.litmus Does a control dependency and an smp_mb() suffice for the load-buffering litmus test, where each process reads from one of two variables then writes to the other? LB+poacquireonce+pooncerelease.litmus Does a release-acquire pair suffice for the load-buffering litmus test, where each process reads from one of two variables then writes to the other? LB+poonceonces.litmus As above, but with store-release replaced with WRITE_ONCE() and load-acquire replaced with READ_ONCE(). MP+onceassign+derefonce.litmus As below, but with rcu_assign_pointer() and an rcu_dereference(). MP+polockmbonce+poacquiresilsil.litmus Protect the access with a lock and an smp_mb__after_spinlock() in one process, and use an acquire load followed by a pair of spin_is_locked() calls in the other process. MP+polockonce+poacquiresilsil.litmus Protect the access with a lock in one process, and use an acquire load followed by a pair of spin_is_locked() calls in the other process. MP+polocks.litmus As below, but with the second access of the writer process and the first access of reader process protected by a lock. MP+poonceonces.litmus As below, but without the smp_rmb() and smp_wmb(). MP+pooncerelease+poacquireonce.litmus As below, but with a release-acquire chain. MP+porevlocks.litmus As below, but with the first access of the writer process and the second access of reader process protected by a lock. MP+fencewmbonceonce+fencermbonceonce.litmus Does a smp_wmb() (between the stores) and an smp_rmb() (between the loads) suffice for the message-passing litmus test, where one process writes data and then a flag, and the other process reads the flag and then the data. (This is similar to the ISA2 tests, but with two processes instead of three.) R+fencembonceonces.litmus This is the fully ordered (via smp_mb()) version of one of the classic counterintuitive litmus tests that illustrates the effects of store propagation delays. R+poonceonces.litmus As above, but without the smp_mb() invocations. SB+fencembonceonces.litmus This is the fully ordered (again, via smp_mb() version of store buffering, which forms the core of Dekker's mutual-exclusion algorithm. SB+poonceonces.litmus As above, but without the smp_mb() invocations. SB+rfionceonce-poonceonces.litmus This litmus test demonstrates that LKMM is not fully multicopy atomic. (Neither is it other multicopy atomic.) This litmus test also demonstrates the "locations" debugging aid, which designates additional registers and locations to be printed out in the dump of final states in the herd7 output. Without the "locations" statement, only those registers and locations mentioned in the "exists" clause will be printed. S+poonceonces.litmus As below, but without the smp_wmb() and acquire load. S+fencewmbonceonce+poacquireonce.litmus Can a smp_wmb(), instead of a release, and an acquire order a prior store against a subsequent store? WRC+poonceonces+Once.litmus WRC+pooncerelease+fencermbonceonce+Once.litmus These two are members of an extension of the MP litmus-test class in which the first write is moved to a separate process. The second is forbidden because smp_store_release() is A-cumulative in LKMM. Z6.0+pooncelock+pooncelock+pombonce.litmus Is the ordering provided by a spin_unlock() and a subsequent spin_lock() sufficient to make ordering apparent to accesses by a process not holding the lock? Z6.0+pooncelock+poonceLock+pombonce.litmus As above, but with smp_mb__after_spinlock() immediately following the spin_lock(). Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus Is the ordering provided by a release-acquire chain sufficient to make ordering apparent to accesses by a process that does not participate in that release-acquire chain? A great many more litmus tests are available here: https://github.com/paulmckrcu/litmus