From: "Paul E. McKenney" <paulmck@kernel.org>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jonas Oberhauser <jonas.oberhauser@huawei.com>,
Peter Zijlstra <peterz@infradead.org>,
"parri.andrea" <parri.andrea@gmail.com>, will <will@kernel.org>,
"boqun.feng" <boqun.feng@gmail.com>, npiggin <npiggin@gmail.com>,
dhowells <dhowells@redhat.com>, "j.alglave" <j.alglave@ucl.ac.uk>,
"luc.maranget" <luc.maranget@inria.fr>, akiyks <akiyks@gmail.com>,
dlustig <dlustig@nvidia.com>, joel <joel@joelfernandes.org>,
urezki <urezki@gmail.com>,
quic_neeraju <quic_neeraju@quicinc.com>,
frederic <frederic@kernel.org>,
Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: Internal vs. external barriers (was: Re: Interesting LKMM litmus test)
Date: Sun, 15 Jan 2023 20:23:29 -0800 [thread overview]
Message-ID: <20230116042329.GN2948950@paulmck-ThinkPad-P17-Gen-1> (raw)
In-Reply-To: <Y8RmEtBnwqOzNhsK@rowland.harvard.edu>
On Sun, Jan 15, 2023 at 03:46:10PM -0500, Alan Stern wrote:
> On Sun, Jan 15, 2023 at 10:10:52AM -0800, Paul E. McKenney wrote:
> > On Sun, Jan 15, 2023 at 11:23:31AM -0500, Alan Stern wrote:
> > > On Sat, Jan 14, 2023 at 09:15:10PM -0800, Paul E. McKenney wrote:
> > > > What am I missing here?
> > >
> > > I don't think you're missing anything. This is a matter for Boqun or
> > > Luc; it must have something to do with the way herd treats the
> > > srcu_read_lock() and srcu_read_unlock() primitives.
> >
> > It looks like we need something that tracks (data | rf)* between
> > the return value of srcu_read_lock() and the second parameter of
> > srcu_read_unlock(). The reason for rf rather than rfi is the upcoming
> > srcu_down_read() and srcu_up_read().
>
> Or just make herd treat srcu_read_lock(s) as an annotated equivalent of
> READ_ONCE(&s) and srcu_read_unlock(s, v) as an annotated equivalent of
> WRITE_ONCE(s, v). But with some special accomodation to avoid
> interaction with the new carry-dep relation.
This is a modification to herd7 you are suggesting? Otherwise, I am
suffering a failure of imagination on how to properly sort it from the
other READ_ONCE() and WRITE_ONCE() instances.
> > But what I will do in the meantime is to switch back to a commit that
> > simply flags nesting of same-srcu_struct SRCU read-side critical sections,
> > while blindly assuming that the return value of a given srcu_read_lock()
> > is passed in to the corresponding srcu_read_unlock():
> >
> > ------------------------------------------------------------------------
> >
> > (* Compute matching pairs of Srcu-lock and Srcu-unlock, but prohibit nesting *)
> > let srcu-unmatched = Srcu-lock | Srcu-unlock
> > let srcu-unmatched-po = ([srcu-unmatched] ; po ; [srcu-unmatched]) & loc
> > let srcu-unmatched-locks-to-unlock = ([Srcu-lock] ; po ; [Srcu-unlock]) & loc
> > let srcu-rscs = srcu-unmatched-locks-to-unlock \ (srcu-unmatched-po ; srcu-unmatched-po)
> >
> > (* Validate nesting *)
> > flag ~empty Srcu-lock \ domain(srcu-rscs) as unbalanced-srcu-locking
> > flag ~empty Srcu-unlock \ range(srcu-rscs) as unbalanced-srcu-locking
> >
> > (* Check for use of synchronize_srcu() inside an RCU critical section *)
> > flag ~empty rcu-rscs & (po ; [Sync-srcu] ; po) as invalid-sleep
> >
> > (* Validate SRCU dynamic match *)
> > flag ~empty different-values(srcu-rscs) as srcu-bad-nesting
> >
> > ------------------------------------------------------------------------
> >
> > Or is there some better intermediate position that could be taken?
>
> Do you mean go back to the current linux-kernel.bell? The code you
> wrote above is different, since it prohibits nesting.
Not to the current linux-kernel.bell, but, as you say, making the change
to obtain a better approximation by prohibiting nesting.
Thanx, Paul
next prev parent reply other threads:[~2023-01-16 4:23 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220921173109.GA1214281@paulmck-ThinkPad-P17-Gen-1>
[not found] ` <YytfFiMT2Xsdwowf@rowland.harvard.edu>
[not found] ` <YywXuzZ/922LHfjI@hirez.programming.kicks-ass.net>
[not found] ` <114ECED5-FED1-4361-94F7-8D9BC02449B7>
[not found] ` <YzSAnclenTz7KQyt@rowland.harvard.edu>
[not found] ` <f763bd5ff835458d8750b61da47fe316@huawei.com>
2023-01-03 18:56 ` Internal vs. external barriers (was: Re: Interesting LKMM litmus test) Alan Stern
2023-01-04 15:37 ` Andrea Parri
2023-01-04 20:58 ` Alan Stern
[not found] ` <ee186bc17a5e48298a5373f688496dce@huawei.com>
2023-01-05 17:32 ` Paul E. McKenney
[not found] ` <bea712c82e6346f8973399a5711ff78a@huawei.com>
2023-01-11 15:06 ` Alan Stern
[not found] ` <768ffe7edc7f4ddfacd5b0a8e844ed84@huawei.com>
2023-01-11 17:01 ` Alan Stern
[not found] ` <07579baee4b84532a76ea8b0b33052bb@huawei.com>
2023-01-12 21:57 ` Paul E. McKenney
2023-01-13 16:38 ` Alan Stern
2023-01-13 19:54 ` Paul E. McKenney
[not found] ` <06a8aef7eb8d46bca34521a80880dae3@huawei.com>
2023-01-14 17:42 ` Paul E. McKenney
[not found] ` <e51c82a113484b6bb62354a49376f248@huawei.com>
2023-01-14 16:42 ` Alan Stern
2023-01-17 17:48 ` Jonas Oberhauser
2023-01-17 21:19 ` Alan Stern
2023-01-18 11:25 ` Jonas Oberhauser
2023-01-19 2:28 ` Alan Stern
2023-01-19 11:22 ` Jonas Oberhauser
2023-01-19 16:41 ` Alan Stern
2023-01-19 18:43 ` Paul E. McKenney
2023-01-23 16:16 ` Jonas Oberhauser
2023-01-23 19:58 ` Alan Stern
2023-01-23 20:06 ` Jonas Oberhauser
2023-01-23 20:41 ` Alan Stern
2023-01-24 13:21 ` Jonas Oberhauser
2023-01-24 15:54 ` Jonas Oberhauser
2023-01-24 17:22 ` Alan Stern
[not found] ` <4c1abc7733794519ad7c5153ae8b58f9@huawei.com>
2023-01-13 16:28 ` Alan Stern
2023-01-13 20:07 ` Paul E. McKenney
2023-01-13 20:32 ` Paul E. McKenney
2023-01-14 17:40 ` Alan Stern
2023-01-14 17:48 ` Paul E. McKenney
[not found] ` <136d019d8c8049f6b737627df830e66f@huawei.com>
2023-01-14 17:53 ` Paul E. McKenney
2023-01-14 18:15 ` Paul E. McKenney
2023-01-14 19:58 ` Alan Stern
2023-01-15 5:19 ` Paul E. McKenney
2023-01-14 20:19 ` Alan Stern
2023-01-15 5:15 ` Paul E. McKenney
2023-01-15 16:23 ` Alan Stern
2023-01-15 18:10 ` Paul E. McKenney
2023-01-15 20:46 ` Alan Stern
2023-01-16 4:23 ` Paul E. McKenney [this message]
2023-01-16 18:11 ` Alan Stern
2023-01-16 19:06 ` Paul E. McKenney
2023-01-16 19:20 ` Alan Stern
2023-01-16 22:13 ` Paul E. McKenney
2023-01-17 11:46 ` Andrea Parri
2023-01-17 15:14 ` Paul E. McKenney
2023-01-17 15:56 ` Alan Stern
2023-01-17 17:43 ` Paul E. McKenney
2023-01-17 18:27 ` Jonas Oberhauser
2023-01-17 18:55 ` Paul E. McKenney
2023-01-17 20:20 ` Jonas Oberhauser
2023-01-17 20:15 ` Alan Stern
2023-01-18 3:50 ` Paul E. McKenney
2023-01-18 16:50 ` Alan Stern
2023-01-18 19:42 ` Jonas Oberhauser
2023-01-18 20:19 ` Paul E. McKenney
2023-01-18 20:30 ` Jonas Oberhauser
2023-01-18 21:12 ` Paul E. McKenney
2023-01-18 21:24 ` Jonas Oberhauser
2023-01-19 0:11 ` Paul E. McKenney
2023-01-19 13:39 ` Jonas Oberhauser
2023-01-19 18:41 ` Paul E. McKenney
2023-01-19 19:51 ` Alan Stern
2023-01-19 21:53 ` Paul E. McKenney
2023-01-19 22:04 ` Alan Stern
2023-01-19 23:03 ` Paul E. McKenney
2023-01-20 9:43 ` Jonas Oberhauser
2023-01-20 15:39 ` Paul E. McKenney
2023-01-20 20:46 ` Jonas Oberhauser
2023-01-20 21:37 ` Paul E. McKenney
2023-01-20 22:36 ` Jonas Oberhauser
2023-01-20 23:19 ` Paul E. McKenney
2023-01-21 0:03 ` Jonas Oberhauser
2023-01-21 0:34 ` Paul E. McKenney
2023-01-20 3:55 ` Paul E. McKenney
2023-01-20 9:20 ` Jonas Oberhauser
2023-01-20 12:34 ` Jonas Oberhauser
2023-01-20 12:51 ` Jonas Oberhauser
2023-01-20 15:32 ` Paul E. McKenney
2023-01-20 20:56 ` Jonas Oberhauser
2023-01-20 21:40 ` Paul E. McKenney
2023-01-20 16:14 ` Alan Stern
2023-01-20 17:30 ` Paul E. McKenney
2023-01-20 18:15 ` Alan Stern
2023-01-20 18:59 ` Paul E. McKenney
2023-01-20 10:13 ` Jonas Oberhauser
2023-01-20 15:47 ` Paul E. McKenney
2023-01-20 22:21 ` Jonas Oberhauser
2023-01-20 16:18 ` Alan Stern
2023-01-20 21:41 ` Jonas Oberhauser
2023-01-21 4:38 ` Paul E. McKenney
2023-01-21 17:36 ` Alan Stern
2023-01-21 18:40 ` Paul E. McKenney
2023-01-21 19:56 ` Alan Stern
2023-01-21 20:10 ` Paul E. McKenney
2023-01-21 21:03 ` Alan Stern
2023-01-21 23:49 ` Paul E. McKenney
2023-01-23 11:48 ` Jonas Oberhauser
2023-01-23 15:55 ` Alan Stern
2023-01-23 19:40 ` Jonas Oberhauser
2023-01-23 20:34 ` Alan Stern
2023-01-18 20:06 ` Paul E. McKenney
2023-01-18 20:54 ` Alan Stern
2023-01-18 21:05 ` Jonas Oberhauser
2023-01-19 0:02 ` Paul E. McKenney
2023-01-19 2:19 ` Alan Stern
2023-01-19 11:23 ` Paul E. McKenney
2023-01-20 16:01 ` Alan Stern
2023-01-20 17:58 ` Paul E. McKenney
2023-01-20 18:37 ` Alan Stern
2023-01-20 19:20 ` Paul E. McKenney
2023-01-20 20:36 ` Alan Stern
2023-01-20 21:20 ` Paul E. McKenney
2023-01-22 20:32 ` Alan Stern
2023-01-23 20:16 ` Paul E. McKenney
2023-01-24 2:18 ` Alan Stern
2023-01-24 4:06 ` Paul E. McKenney
2023-01-24 11:09 ` Andrea Parri
2023-01-24 14:54 ` Paul E. McKenney
2023-01-24 15:11 ` Jonas Oberhauser
2023-01-24 16:22 ` Paul E. McKenney
2023-01-24 16:39 ` Jonas Oberhauser
2023-01-24 17:26 ` Paul E. McKenney
2023-01-24 19:30 ` Jonas Oberhauser
2023-01-24 22:15 ` Paul E. McKenney
2023-01-24 22:35 ` Alan Stern
2023-01-24 22:54 ` Paul E. McKenney
2023-01-25 1:54 ` Alan Stern
2023-01-25 2:20 ` Paul E. McKenney
2023-01-25 13:10 ` Jonas Oberhauser
2023-01-25 15:05 ` Paul E. McKenney
2023-01-25 15:34 ` Alan Stern
2023-01-25 17:18 ` Paul E. McKenney
2023-01-25 17:42 ` Jonas Oberhauser
2023-01-25 19:08 ` Alan Stern
2023-01-25 19:46 ` Paul E. McKenney
2023-01-25 20:36 ` Andrea Parri
2023-01-25 21:10 ` Jonas Oberhauser
2023-01-25 21:23 ` Paul E. McKenney
2023-01-25 20:46 ` Alan Stern
2023-01-25 21:38 ` Paul E. McKenney
2023-01-25 23:33 ` Paul E. McKenney
2023-01-26 1:45 ` Alan Stern
2023-01-26 1:53 ` Paul E. McKenney
2023-01-26 12:17 ` Jonas Oberhauser
2023-01-26 18:48 ` Paul E. McKenney
2023-01-27 15:03 ` Jonas Oberhauser
2023-01-27 16:50 ` Paul E. McKenney
2023-01-27 16:54 ` Paul E. McKenney
2023-01-18 19:57 ` Jonas Oberhauser
2023-01-18 21:06 ` Paul E. McKenney
2023-01-18 2:15 ` Alan Stern
2023-01-18 5:17 ` Paul E. McKenney
2023-01-18 16:03 ` Alan Stern
2023-01-18 16:59 ` Boqun Feng
2023-01-18 17:08 ` Alan Stern
2023-01-18 17:41 ` Paul E. McKenney
2023-01-19 19:07 ` Paul E. McKenney
2023-01-14 16:55 ` Alan Stern
2023-01-14 17:35 ` Paul E. McKenney
[not found] ` <17078dd97cb6480f9c51e27058af3197@huawei.com>
2023-01-14 17:27 ` Alan Stern
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