Messages in this thread | | | Date | Thu, 30 Sep 2021 16:46:34 -0400 | From | Alan Stern <> | Subject | Re: [PATCH] tools/memory-model: Provide extra ordering for unlock+lock pair on the same CPU |
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On Thu, Sep 30, 2021 at 11:17:53AM -0700, Paul E. McKenney wrote: > On Thu, Sep 30, 2021 at 11:20:33AM -0400, Alan Stern wrote: > > On Thu, Sep 30, 2021 at 09:08:23PM +0800, Boqun Feng wrote: > > > A recent discussion[1] shows that we are in favor of strengthening the > > > ordering of unlock + lock on the same CPU: a unlock and a po-after lock > > > should provide the so-called RCtso ordering, that is a memory access S > > > po-before the unlock should be ordered against a memory access R > > > po-after the lock, unless S is a store and R is a load. > > > > > > The strengthening meets programmers' expection that "sequence of two > > > locked regions to be ordered wrt each other" (from Linus), and can > > > reduce the mental burden when using locks. Therefore add it in LKMM. > > > > > > [1]: https://lore.kernel.org/lkml/20210909185937.GA12379@rowland.harvard.edu/ > > > > > > Co-developed-by: Alan Stern <stern@rowland.harvard.edu> > > > Signed-off-by: Alan Stern <stern@rowland.harvard.edu> > > > Signed-off-by: Boqun Feng <boqun.feng@gmail.com> > > > --- > > > Alan, > > > > > > I added the "Co-developed-by" and "Signed-off-by" tags since most of the > > > work is done by you. Feel free to let me know if you want to change > > > anything. > > > > It looks good to me. However, do we really want to add these litmus > > tests to the kernel source, or would it be better to keep them with > > the thousands of other tests in Paul's archives? > > Either way works for me. But if they are referred to from within the > kernel, it is best to have them in the kernel source. Which might be seen > as a reason to minimize referring to litmus tests from the kernel. ;-)
In this case the litmus tests are not referred to within the kernel source.
Alan
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