mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-02 08:34:20 +08:00
8f32543b61
This commit adds comments to the litmus tests summarizing what these tests are intended to demonstrate. [ paulmck: Apply Andrea's and Alan's feedback. ] Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: nborisov@suse.com Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: stern@rowland.harvard.edu Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1519169112-20593-4-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
40 lines
784 B
Plaintext
40 lines
784 B
Plaintext
C ISA2+pooncerelease+poacquirerelease+poacquireonce
|
|
|
|
(*
|
|
* Result: Never
|
|
*
|
|
* This litmus test demonstrates that a release-acquire chain suffices
|
|
* to order P0()'s initial write against P2()'s final read. The reason
|
|
* that the release-acquire chain suffices is because in all but one
|
|
* case (P2() to P0()), each process reads from the preceding process's
|
|
* write. In memory-model-speak, there is only one non-reads-from
|
|
* (AKA non-rf) link, so release-acquire is all that is needed.
|
|
*)
|
|
|
|
{}
|
|
|
|
P0(int *x, int *y)
|
|
{
|
|
WRITE_ONCE(*x, 1);
|
|
smp_store_release(y, 1);
|
|
}
|
|
|
|
P1(int *y, int *z)
|
|
{
|
|
int r0;
|
|
|
|
r0 = smp_load_acquire(y);
|
|
smp_store_release(z, 1);
|
|
}
|
|
|
|
P2(int *x, int *z)
|
|
{
|
|
int r0;
|
|
int r1;
|
|
|
|
r0 = smp_load_acquire(z);
|
|
r1 = READ_ONCE(*x);
|
|
}
|
|
|
|
exists (1:r0=1 /\ 2:r0=1 /\ 2:r1=0)
|