The four litmus tests in Documentation/litmus-tests/atomic do not
declare all of their local variables. Although this is just fine for LKMM
analysis by herd7, it causes build failures when run in-kernel by klitmus.
This commit therefore adjusts these tests to declare all local variables.
Reported-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
This commit adds four litmus tests showing that a failing cmpxchg()
operation is unordered unless followed by an smp_mb__after_atomic()
operation.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <linux-arch@vger.kernel.org>
Cc: <linux-doc@vger.kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
This commit documents the litmus tests in the "locking" directory.
[ paulmck: Apply formatting feedback from Andrea Parri. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <linux-arch@vger.kernel.org>
Cc: <linux-doc@vger.kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
This update improves litmus-test documentation and improves the ability
to do before/after tests on the https://github.com/paulmckrcu/litmus repo.
-----BEGIN PGP SIGNATURE-----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=kQ01
-----END PGP SIGNATURE-----
Merge tag 'lkmm-scripting.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull Linux Kernel Memory Model scripting updates from Paul McKenney:
"This improves litmus-test documentation and improves the ability to do
before/after tests on the https://github.com/paulmckrcu/litmus repo"
* tag 'lkmm-scripting.2023.04.07a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (32 commits)
tools/memory-model: Remove out-of-date SRCU documentation
tools/memory-model: Document LKMM test procedure
tools/memory-model: Use "grep -E" instead of "egrep"
tools/memory-model: Use "-unroll 0" to keep --hw runs finite
tools/memory-model: Make judgelitmus.sh handle scripted Result: tag
tools/memory-model: Add data-race capabilities to judgelitmus.sh
tools/memory-model: Add checktheselitmus.sh to run specified litmus tests
tools/memory-model: Repair parseargs.sh header comment
tools/memory-model: Add "--" to parseargs.sh for additional arguments
tools/memory-model: Make history-check scripts use mselect7
tools/memory-model: Make checkghlitmus.sh use mselect7
tools/memory-model: Fix scripting --jobs argument
tools/memory-model: Implement --hw support for checkghlitmus.sh
tools/memory-model: Add -v flag to jingle7 runs
tools/memory-model: Make runlitmus.sh check for jingle errors
tools/memory-model: Allow herd to deduce CPU type
tools/memory-model: Keep assembly-language litmus tests
tools/memory-model: Move from .AArch64.litmus.out to .litmus.AArch.out
tools/memory-model: Make runlitmus.sh generate .litmus.out for --hw
tools/memory-model: Split runlitmus.sh out of checklitmus.sh
...
Most Linux-kernel uses of locking are straightforward, but there are
corner-case uses that rely on less well-known aspects of the lock and
unlock primitives. This commit therefore adds a locking.txt and litmus
tests in Documentation/litmus-tests/locking to explain these corner-case
uses.
[ paulmck: Apply Andrea Parri feedback for klitmus7. ]
[ paulmck: Apply Akira Yokosawa example-consistency feedback. ]
Reviewed-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Correct spelling problems for Documentation/litmus-tests/ as reported
by codespell.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: linux-arch@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
herdtools 7.56 has enhanced herd7's C parser so that the "(void)expr"
construct in Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus is
accepted.
This is independent of LKMM's cat model, so mention the required
version in the header of the litmus test and its entry in README.
CC: Boqun Feng <boqun.feng@gmail.com>
Reported-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit cites a pertinent RCU-related litmus test.
Co-developed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Co-developed-by: Akira Yokosawa <akiyks@gmail.com>
[Alan: grammar nit]
[ paulmck: Update commit log and title per Akira feedback. ]
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Where Documentation/litmus-tests/README lists RCU litmus tests,
Documentation/litmus-tests/atomic/README lists atomic litmus tests.
For symmetry, merge the latter into former, with some context
adjustment in the introduction.
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
We already use a litmus test in atomic_t.txt to describe atomic RMW +
smp_mb__after_atomic() is stronger than acquire (both the read and the
write parts are ordered). So make it a litmus test in atomic-tests
directory, so that people can access the litmus easily.
Additionally, change the processor numbers "P1, P2" to "P0, P1" in
atomic_t.txt for the consistency with the processor numbers in the
litmus test, which herd can handle.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
We already use a litmus test in atomic_t.txt to describe the behavior of
an atomic_set() with the an atomic RMW, so add it into atomic-tests
directory to make it easily accessible for anyone who cares about the
semantics of our atomic APIs.
Besides currently the litmus test "atomic-set" in atomic_t.txt has a few
things to be improved:
1) The CPU/Processor numbers "P1,P2" are not only inconsistent with
the rest of the document, which uses "CPU0" and "CPU1", but also
unacceptable by the herd tool, which requires processors start
at "P0".
2) The initialization block uses a "atomic_set()", which is OK, but
it's better to use ATOMIC_INIT() to make clear this is an
initialization.
3) The return value of atomic_add_unless() is discarded
inexplicitly, which is OK for C language, but it will be helpful
to the herd tool if we use a void cast to make the discard
explicit.
4) The name and the paragraph describing the test need to be more
accurate and aligned with our wording in LKMM.
Therefore fix these in both atomic_t.txt and the new added litmus test.
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Although we have atomic_t.txt and its friends to describe the semantics
of atomic APIs and lib/atomic64_test.c for build testing and testing in
UP mode, the tests for our atomic APIs in real SMP mode are still
missing. Since now we have the LKMM tool in kernel and litmus tests can
be used to generate kernel modules for testing purpose with "klitmus" (a
tool from the LKMM toolset), it makes sense to put a few typical litmus
tests into kernel so that
1) they are the examples to describe the conceptual mode of the
semantics of atomic APIs, and
2) they can be used to generate kernel test modules for anyone
who is interested to test the atomic APIs implementation (in
most cases, is the one who implements the APIs for a new arch)
Therefore, introduce the atomic directory for this purpose. The
directory is maintained by the LKMM group to make sure the litmus tests
are always aligned with our memory model.
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This adds an example for the important RCU grace period guarantee, which
shows an RCU reader can never span a grace period.
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This adds an example for the important RCU grace period guarantee, which
shows an RCU reader can never span a grace period.
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Paul E. McKenney