linux-stable.git/tools/memory-model, branch v4.19.321

tools/memory-model: Fix bug in lock.cat

2024-08-19T03:32:04+00:00

commit 4c830eef806679dc243e191f962c488dd9d00708 upstream.

Andrea reported that the following innocuous litmus test:

C T

{}

P0(spinlock_t *x)
{
	int r0;

	spin_lock(x);
	spin_unlock(x);
	r0 = spin_is_locked(x);
}

gives rise to a nonsensical empty result with no executions:

$ herd7 -conf linux-kernel.cfg T.litmus
Test T Required
States 0
Ok
Witnesses
Positive: 0 Negative: 0
Condition forall (true)
Observation T Never 0 0
Time T 0.00
Hash=6fa204e139ddddf2cb6fa963bad117c0

The problem is caused by a bug in the lock.cat part of the LKMM.  Its
computation of the rf relation for RU (read-unlocked) events is
faulty; it implicitly assumes that every RU event must read from
either a UL (unlock) event in another thread or from the lock's
initial state.  Neither is true in the litmus test above, so the
computation yields no possible executions.

The lock.cat code tries to make up for this deficiency by allowing RU
events outside of critical sections to read from the last po-previous
UL event.  But it does this incorrectly, trying to keep these rfi links
separate from the rfe links that might also be needed, and passing only
the latter to herd7's cross() macro.

The problem is fixed by merging the two sets of possible rf links for
RU events and using them all in the call to cross().

Signed-off-by: Alan Stern 
Reported-by: Andrea Parri 
Closes: https://lore.kernel.org/linux-arch/ZlC0IkzpQdeGj+a3@andrea/
Tested-by: Andrea Parri 
Acked-by: Andrea Parri 
Fixes: 15553dcbca06 ("tools/memory-model: Add model support for spin_is_locked()")
CC: 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

tools/memory-model: Rename litmus tests to comply to norm7

2018-07-17T07:30:36+00:00

norm7 produces the 'normalized' name of a litmus test,  when the test
can be generated from a single cycle that passes through each process
exactly once. The commit renames such tests in order to comply to the
naming scheme implemented by this tool.

Signed-off-by: Andrea Parri 
Signed-off-by: Paul E. McKenney 
Acked-by: Alan Stern 
Cc: Akira Yokosawa 
Cc: Boqun Feng 
Cc: David Howells 
Cc: Jade Alglave 
Cc: Linus Torvalds 
Cc: Luc Maranget 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-14-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model/Documentation: Fix typo, smb->smp

2018-07-17T07:30:35+00:00

The tools/memory-model/Documentation/explanation.txt file says
"For each other CPU C', smb_wmb() forces all po-earlier stores"
This commit therefore replaces the "smb_wmb()" with "smp_wmb()".

Signed-off-by: Yauheni Kaliuta 
Signed-off-by: Paul E. McKenney 
Acked-by: Alan Stern 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-13-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Make scripts executable

2018-07-17T07:30:17+00:00

This commit makes the scripts executable to avoid the need for everyone
to do so manually in their archive.

Signed-off-by: Paul E. McKenney 
Acked-by: Akira Yokosawa 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-7-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Remove ACCESS_ONCE() from model

2018-07-17T07:29:35+00:00

Since commit:

  b899a850431e2dd0 ("compiler.h: Remove ACCESS_ONCE()")

... there has been no definition of ACCESS_ONCE() in the kernel tree,
and it has been necessary to use READ_ONCE() or WRITE_ONCE() instead.

Correspondingly, let's remove ACCESS_ONCE() from the kernel memory
model.

Signed-off-by: Mark Rutland 
Signed-off-by: Paul E. McKenney 
Acked-by: Andrea Parri 
Cc: Akira Yokosawa 
Cc: Alan Stern 
Cc: Boqun Feng 
Cc: David Howells 
Cc: Jade Alglave 
Cc: Linus Torvalds 
Cc: Luc Maranget 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-6-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Remove ACCESS_ONCE() from recipes

2018-07-17T07:29:34+00:00

Since commit:

  b899a850431e2dd0 ("compiler.h: Remove ACCESS_ONCE()")

... there has been no definition of ACCESS_ONCE() in the kernel tree,
and it has been necessary to use READ_ONCE() or WRITE_ONCE() instead.

Let's update the exmaples in recipes.txt likewise for consistency, using
READ_ONCE() for reads.

Signed-off-by: Mark Rutland 
Signed-off-by: Paul E. McKenney 
Acked-by: Andrea Parri 
Cc: Akira Yokosawa 
Cc: Alan Stern 
Cc: Boqun Feng 
Cc: David Howells 
Cc: Jade Alglave 
Cc: Linus Torvalds 
Cc: Luc Maranget 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-5-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Fix ISA2+pooncelock+pooncelock+pombonce name

2018-07-17T07:29:31+00:00

The names on the first line of the litmus tests are arbitrary,
but the convention is that they be the filename without the trailing
".litmus".  This commit therefore removes the stray trailing ".litmus"
from ISA2+pooncelock+pooncelock+pombonce.litmus's name.

Reported-by: Andrea Parri 
Signed-off-by: Paul E. McKenney 
Acked-by: Alan Stern 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-2-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Add litmus test for full multicopy atomicity

2018-07-17T07:29:29+00:00

This commit adds a litmus test suggested by Alan Stern that is forbidden
on fully multicopy atomic systems, but allowed on other-multicopy and
on non-multicopy atomic systems.  For reference, s390 is fully multicopy
atomic, x86 and ARMv8 are other-multicopy atomic, and ARMv7 and powerpc
are non-multicopy atomic.

Suggested-by: Alan Stern 
Signed-off-by: Paul E. McKenney 
Acked-by: Alan Stern 
Acked-by: Andrea Parri 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
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: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/20180716180605.16115-1-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Add reference for 'Simplifying ARM concurrency'

2018-05-15T06:11:19+00:00

The paper discusses the revised ARMv8 memory model; such revision
had an important impact on the design of the LKMM.

Signed-off-by: Andrea Parri 
Signed-off-by: Paul E. McKenney 
Cc: Akira Yokosawa 
Cc: Alan Stern 
Cc: Andrew Morton 
Cc: Boqun Feng 
Cc: David Howells 
Cc: Jade Alglave 
Cc: Linus Torvalds 
Cc: Luc Maranget 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/1526340837-12222-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

tools/memory-model: Update ASPLOS information

2018-05-15T06:11:18+00:00

ASPLOS 2018 was held in March: make sure this is reflected in
header comments and references.

Signed-off-by: Andrea Parri 
Signed-off-by: Paul E. McKenney 
Cc: Akira Yokosawa 
Cc: Alan Stern 
Cc: Andrew Morton 
Cc: Boqun Feng 
Cc: David Howells 
Cc: Jade Alglave 
Cc: Linus Torvalds 
Cc: Luc Maranget 
Cc: Nicholas Piggin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/1526340837-12222-18-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar