17 Jul, 2018
1 commit
-
Both the implementation and the users' expectation [1] for the various
wakeup primitives have evolved over time, but the documentation has not
kept up with these changes: brings it into 2018.[1] http://lkml.kernel.org/r/20180424091510.GB4064@hirez.programming.kicks-ass.net
Also applied feedback from Alan Stern.
Suggested-by: Peter Zijlstra
Signed-off-by: Andrea Parri
Signed-off-by: Paul E. McKenney
Acked-by: Peter Zijlstra (Intel)
Cc: Akira Yokosawa
Cc: Alan Stern
Cc: Boqun Feng
Cc: Daniel Lustig
Cc: David Howells
Cc: Jade Alglave
Cc: Jonathan Corbet
Cc: Linus Torvalds
Cc: Luc Maranget
Cc: Nicholas Piggin
Cc: Thomas Gleixner
Cc: Will Deacon
Cc: linux-arch@vger.kernel.org
Cc: parri.andrea@gmail.com
Link: http://lkml.kernel.org/r/20180716180605.16115-12-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
05 Jun, 2018
1 commit
-
Pull locking updates from Ingo Molnar:
- Lots of tidying up changes all across the map for Linux's formal
memory/locking-model tooling, by Alan Stern, Akira Yokosawa, Andrea
Parri, Paul E. McKenney and SeongJae Park.Notable changes beyond an overall update in the tooling itself is the
tidying up of spin_is_locked() semantics, which spills over into the
kernel proper as well.- qspinlock improvements: the locking algorithm now guarantees forward
progress whereas the previous implementation in mainline could starve
threads indefinitely in cmpxchg() loops. Also other related cleanups
to the qspinlock code (Will Deacon)- misc smaller improvements, cleanups and fixes all across the locking
subsystem* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
locking/rwsem: Simplify the is-owner-spinnable checks
tools/memory-model: Add reference for 'Simplifying ARM concurrency'
tools/memory-model: Update ASPLOS information
MAINTAINERS, tools/memory-model: Update e-mail address for Andrea Parri
tools/memory-model: Fix coding style in 'lock.cat'
tools/memory-model: Remove out-of-date comments and code from lock.cat
tools/memory-model: Improve mixed-access checking in lock.cat
tools/memory-model: Improve comments in lock.cat
tools/memory-model: Remove duplicated code from lock.cat
tools/memory-model: Flag "cumulativity" and "propagation" tests
tools/memory-model: Add model support for spin_is_locked()
tools/memory-model: Add scripts to test memory model
tools/memory-model: Fix coding style in 'linux-kernel.def'
tools/memory-model: Model 'smp_store_mb()'
tools/memory-order: Update the cheat-sheet to show that smp_mb__after_atomic() orders later RMW operations
tools/memory-order: Improve key for SELF and SV
tools/memory-model: Fix cheat sheet typo
tools/memory-model: Update required version of herdtools7
tools/memory-model: Redefine rb in terms of rcu-fence
tools/memory-model: Rename link and rcu-path to rcu-link and rb
...
15 May, 2018
1 commit
-
The section of memory-barriers.txt that describes the dma_Xmb() barriers
has an incorrect example claiming that a wmb() is required after writing
to coherent memory in order for those writes to be visible to a device
before a subsequent MMIO access using writel() can reach the device.In fact, this ordering guarantee is provided (at significant cost on some
architectures such as arm and power) by writel, so the wmb() is not
necessary. writel_relaxed exists for cases where this ordering is not
required.Fix the example and update the text to make this clearer.
Reported-by: Sinan Kaya
Signed-off-by: Will Deacon
Signed-off-by: Paul E. McKenney
Cc: Andrew Morton
Cc: Arnd Bergmann
Cc: Benjamin Herrenschmidt
Cc: Jason Gunthorpe
Cc: Jonathan Corbet
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: stern@rowland.harvard.edu
Link: http://lkml.kernel.org/r/1526338533-6044-1-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
09 May, 2018
2 commits
-
The circular-buffers.txt is already in ReST format. So, move it to the
core-api guide, where it belongs.Signed-off-by: Mauro Carvalho Chehab
Signed-off-by: Jonathan Corbet -
The cachetlb.txt is already in ReST format. So, move it to the
core-api guide, where it belongs.Signed-off-by: Mauro Carvalho Chehab
Signed-off-by: Jonathan Corbet
10 Mar, 2018
1 commit
-
This commit makes further changes to memory-barrier.txt to further
de-emphasize smp_read_barrier_depends(), but leaving some discussion
for historical purposes.Signed-off-by: Paul E. McKenney
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: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1520443660-16858-1-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
21 Feb, 2018
2 commits
-
In the description of data dependency barriers the words 'before' is
used erroneously. Since such barrier order dependent loads one after
the other. So substitute 'before' with 'after'.Signed-off-by: Nikolay Borisov
Signed-off-by: Paul E. McKenney
Acked-by: Peter Zijlstra
Cc: Linus Torvalds
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: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1519169112-20593-8-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
A memory consistency model is now available for the Linux kernel [1],
which "can (roughly speaking) be thought of as an automated version of
memory-barriers.txt" and which is (in turn) "accompanied by extensive
documentation on its use and its design".Inform the (occasional) reader of memory-barriers.txt of these
developments.[1] https://marc.info/?l=linux-kernel&m=151687290114799&w=2
Co-developed-by: Andrea Parri
Co-developed-by: Akira Yokosawa
Signed-off-by: Andrea Parri
Signed-off-by: Akira Yokosawa
Signed-off-by: Paul E. McKenney
Acked-by: Peter Zijlstra
Cc: Linus Torvalds
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: nborisov@suse.com
Cc: npiggin@gmail.com
Cc: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1519169112-20593-7-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
06 Dec, 2017
1 commit
-
This commit keeps only the historical and low-level discussion of
smp_read_barrier_depends().Signed-off-by: Paul E. McKenney
[ paulmck: Adjusted to allow for David Howells feedback on prior commit. ]
05 Dec, 2017
1 commit
-
This commit updates an example in memory-barriers.txt to account for
the fact that READ_ONCE() now implies smp_barrier_depends().Signed-off-by: Paul E. McKenney
[ paulmck: Added MEMORY_BARRIER instructions from DEC Alpha from
READ_ONCE(), per David Howells's feedback. ]
14 Nov, 2017
1 commit
-
Pull core locking updates from Ingo Molnar:
"The main changes in this cycle are:- Another attempt at enabling cross-release lockdep dependency
tracking (automatically part of CONFIG_PROVE_LOCKING=y), this time
with better performance and fewer false positives. (Byungchul Park)- Introduce lockdep_assert_irqs_enabled()/disabled() and convert
open-coded equivalents to lockdep variants. (Frederic Weisbecker)- Add down_read_killable() and use it in the VFS's iterate_dir()
method. (Kirill Tkhai)- Convert remaining uses of ACCESS_ONCE() to
READ_ONCE()/WRITE_ONCE(). Most of the conversion was Coccinelle
driven. (Mark Rutland, Paul E. McKenney)- Get rid of lockless_dereference(), by strengthening Alpha atomics,
strengthening READ_ONCE() with smp_read_barrier_depends() and thus
being able to convert users of lockless_dereference() to
READ_ONCE(). (Will Deacon)- Various micro-optimizations:
- better PV qspinlocks (Waiman Long),
- better x86 barriers (Michael S. Tsirkin)
- better x86 refcounts (Kees Cook)- ... plus other fixes and enhancements. (Borislav Petkov, Juergen
Gross, Miguel Bernal Marin)"* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
locking/x86: Use LOCK ADD for smp_mb() instead of MFENCE
rcu: Use lockdep to assert IRQs are disabled/enabled
netpoll: Use lockdep to assert IRQs are disabled/enabled
timers/posix-cpu-timers: Use lockdep to assert IRQs are disabled/enabled
sched/clock, sched/cputime: Use lockdep to assert IRQs are disabled/enabled
irq_work: Use lockdep to assert IRQs are disabled/enabled
irq/timings: Use lockdep to assert IRQs are disabled/enabled
perf/core: Use lockdep to assert IRQs are disabled/enabled
x86: Use lockdep to assert IRQs are disabled/enabled
smp/core: Use lockdep to assert IRQs are disabled/enabled
timers/hrtimer: Use lockdep to assert IRQs are disabled/enabled
timers/nohz: Use lockdep to assert IRQs are disabled/enabled
workqueue: Use lockdep to assert IRQs are disabled/enabled
irq/softirqs: Use lockdep to assert IRQs are disabled/enabled
locking/lockdep: Add IRQs disabled/enabled assertion APIs: lockdep_assert_irqs_enabled()/disabled()
locking/pvqspinlock: Implement hybrid PV queued/unfair locks
locking/rwlocks: Fix comments
x86/paravirt: Set up the virt_spin_lock_key after static keys get initialized
block, locking/lockdep: Assign a lock_class per gendisk used for wait_for_completion()
workqueue: Remove now redundant lock acquisitions wrt. workqueue flushes
...
24 Oct, 2017
1 commit
-
lockless_dereference() is a nice idea, but it gained little traction in
kernel code since its introduction three years ago. This is partly
because it's a pain to type, but also because using READ_ONCE() instead
has worked correctly on all architectures apart from Alpha, which is a
fully supported but somewhat niche architecture these days.Now that READ_ONCE() has been upgraded to contain an implicit
smp_read_barrier_depends() and the few callers of lockless_dereference()
have been converted, we can remove lockless_dereference() altogether.Signed-off-by: Will Deacon
Cc: Linus Torvalds
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Link: http://lkml.kernel.org/r/1508840570-22169-5-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar
21 Oct, 2017
2 commits
-
The "Write (or store) memory barriers" bullet of the "Variety of memory
barriers" section, calls out a sequential order of stores, which is
confusing since sequential ordering is not guaranteed.This commit therefore rewords to avoid mentioning a sequence of stores
to clarify the intent.Cc: Paul E. McKenney
Signed-off-by: Guilherme G. Piccoli
Signed-off-by: Paul E. McKenney -
In the "general barrier pairing with implicit control depdendency"
example, the last write by CPU 1 was meant to change variable x and not
y. The example would be pretty uninteresting if no CPU ever changes x
and the variable was initialized to zero.Signed-off-by: Scott Tsai
Signed-off-by: Paul E. McKenney
10 Oct, 2017
2 commits
-
Signed-off-by: Alan Stern
Signed-off-by: Paul E. McKenney -
The current version of memory-barriers.txt misuses the term "transitive",
so this commit replaces it with multi-copy atomic, also adding a
definition of this term.Reported-by: Alan Stern
Signed-off-by: Paul E. McKenney
05 Sep, 2017
1 commit
-
Pull locking updates from Ingo Molnar:
- Add 'cross-release' support to lockdep, which allows APIs like
completions, where it's not the 'owner' who releases the lock, to be
tracked. It's all activated automatically under
CONFIG_PROVE_LOCKING=y.- Clean up (restructure) the x86 atomics op implementation to be more
readable, in preparation of KASAN annotations. (Dmitry Vyukov)- Fix static keys (Paolo Bonzini)
- Add killable versions of down_read() et al (Kirill Tkhai)
- Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini)
- Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra)
- Remove smp_mb__before_spinlock() and convert its usages, introduce
smp_mb__after_spinlock() (Peter Zijlstra)* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits)
locking/lockdep/selftests: Fix mixed read-write ABBA tests
sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK()
acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse
locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures
smp: Avoid using two cache lines for struct call_single_data
locking/lockdep: Untangle xhlock history save/restore from task independence
locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being
futex: Remove duplicated code and fix undefined behaviour
Documentation/locking/atomic: Finish the document...
locking/lockdep: Fix workqueue crossrelease annotation
workqueue/lockdep: 'Fix' flush_work() annotation
locking/lockdep/selftests: Add mixed read-write ABBA tests
mm, locking/barriers: Clarify tlb_flush_pending() barriers
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive
locking/lockdep: Explicitly initialize wq_barrier::done::map
locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS
locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config
locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING
locking/refcounts, x86/asm: Implement fast refcount overflow protection
locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease
...
17 Aug, 2017
1 commit
-
The memory-barriers.txt document contains an obsolete passage stating that
smp_read_barrier_depends() is required to force ordering for read-to-write
dependencies. We now know that this is not required, even for DEC Alpha.
This commit therefore updates this passage to state that read-to-write
dependencies are respected even without smp_read_barrier_depends().Reported-by: Lance Roy
Signed-off-by: Paul E. McKenney
Cc: David Howells
Cc: Peter Zijlstra
Cc: Jonathan Corbet
Cc: Alan Stern
Cc: Andrea Parri
Cc: Jade Alglave
Cc: Luc Maranget
[ paulmck: Reference control-dependencies sections and use WRITE_ONCE()
per Will Deacon. Correctly place split-cache paragraph while there. ]
Acked-by: Will Deacon
10 Aug, 2017
2 commits
-
Now that there are no users of smp_mb__before_spinlock() left, remove
it entirely.Signed-off-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Signed-off-by: Ingo Molnar -
Since we've vastly expanded the atomic_t interface in recent years the
existing documentation is woefully out of date and people seem to get
confused a bit.Start a new document to hopefully better explain the current state of
affairs.The old atomic_ops.txt also covers bitmaps and a few more details so
this is not a full replacement and we'll therefore keep that document
around until such a time that we've managed to write more text to cover
its entire.Also please, ReST people, go away.
Signed-off-by: Peter Zijlstra (Intel)
Cc: Boqun Feng
Cc: Linus Torvalds
Cc: Paul McKenney
Cc: Peter Zijlstra
Cc: Randy Dunlap
Cc: Thomas Gleixner
Cc: Will Deacon
Signed-off-by: Ingo Molnar
14 Jul, 2017
1 commit
-
Pull documentation fixes from Jonathan Corbet:
"A set of fixes for various warnings, including the one caused by the
removal of kernel/rcu/srcu.c. Also correct a stray pointer in
memory-barriers.txt"* tag '4.13-fixes' of git://git.lwn.net/linux:
kokr/memory-barriers.txt: Fix obsolete link to atomic_ops.txt
memory-barriers.txt: Fix broken link to atomic_ops.txt
docs: Turn off section numbering for the input docs
docs: Include uaccess docs from the right file
docs: Do not include from kernel/rcu/srcu.c
13 Jul, 2017
1 commit
-
Few obsolete links to atomic_ops.txt exist in memory-barriers.txt though
the file has moved to core-api/atomic_ops.rst. This commit fixes the
obsolete links.Signed-off-by: SeongJae Park
Signed-off-by: Jonathan Corbet
04 Jul, 2017
1 commit
-
Pull documentation updates from Jonathan Corbet:
"There has been a fair amount of activity in the docs tree this time
around. Highlights include:- Conversion of a bunch of security documentation into RST
- The conversion of the remaining DocBook templates by The Amazing
Mauro Machine. We can now drop the entire DocBook build chain.- The usual collection of fixes and minor updates"
* tag 'docs-4.13' of git://git.lwn.net/linux: (90 commits)
scripts/kernel-doc: handle DECLARE_HASHTABLE
Documentation: atomic_ops.txt is core-api/atomic_ops.rst
Docs: clean up some DocBook loose ends
Make the main documentation title less Geocities
Docs: Use kernel-figure in vidioc-g-selection.rst
Docs: fix table problems in ras.rst
Docs: Fix breakage with Sphinx 1.5 and upper
Docs: Include the Latex "ifthen" package
doc/kokr/howto: Only send regression fixes after -rc1
docs-rst: fix broken links to dynamic-debug-howto in kernel-parameters
doc: Document suitability of IBM Verse for kernel development
Doc: fix a markup error in coding-style.rst
docs: driver-api: i2c: remove some outdated information
Documentation: DMA API: fix a typo in a function name
Docs: Insert missing space to separate link from text
doc/ko_KR/memory-barriers: Update control-dependencies example
Documentation, kbuild: fix typo "minimun" -> "minimum"
docs: Fix some formatting issues in request-key.rst
doc: ReSTify keys-trusted-encrypted.txt
doc: ReSTify keys-request-key.txt
...
24 Jun, 2017
1 commit
-
I was reading the memory barries documentation in order to make sure the
RISC-V barries were correct, and I found a broken link to the atomic
operations documentation.Signed-off-by: Palmer Dabbelt
Acked-by: Will Deacon
Acked-by: Paul E. McKenney
Signed-off-by: Jonathan Corbet
08 Jun, 2017
1 commit
-
This commit changes "architecure" to the correct spelling,
"architecture".Signed-off-by: Stan Drozd
Signed-off-by: Paul E. McKenney
12 May, 2017
1 commit
-
Pull more documentation updates from Jonathan Corbet:
"Connect the newly RST-formatted documentation to the rest; this had to
wait until the input pull was done. There's also a few small fixes
that wandered in"* tag 'docs-4.12-2' of git://git.lwn.net/linux:
doc: replace FTP URL to kernel.org with HTTPS one
docs: update references to the device io book
Documentation: earlycon: fix Marvell Armada 3700 UART name
docs-rst: add input docs at main index and use kernel-figure
10 May, 2017
1 commit
-
While converting the deviceiobook from DocBook to RST, dangling
references were left behind. This commit updates all remaining
references to the new location. SeongJae Park improved the ko_KR
translation.Fixes: 8a8a602fdb83 ("docs: Convert the deviceio template to RST")
Signed-off-by: Helmut Grohne
Signed-off-by: SeongJae Park
Signed-off-by: Jonathan Corbet
12 Apr, 2017
1 commit
-
In the following example, if MAX is defined to be 1, then the compiler
knows (Q % MAX) is equal to zero. The compiler can therefore throw
away the "then" branch (and the "if"), retaining only the "else" branch.q = READ_ONCE(a);
if (q % MAX) {
WRITE_ONCE(b, 1);
do_something();
} else {
WRITE_ONCE(b, 2);
do_something_else();
}It is therefore necessary to modify the example like this:
q = READ_ONCE(a);
- WRITE_ONCE(b, 1);
+ WRITE_ONCE(b, 2);
do_something_else();Signed-off-by: pierre Kuo
Acked-by: Will Deacon
Signed-off-by: Paul E. McKenney
15 Jan, 2017
1 commit
-
This commit adds consistency to examples, formatting, and a couple of
additional warnings.Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
12 Aug, 2016
3 commits
-
An example result for data dependent write has a typo. This commit
fixes the wrong typo.Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: dhowells@redhat.com
Cc: linux-arch@vger.kernel.org
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1470939463-31950-3-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: dhowells@redhat.com
Cc: linux-arch@vger.kernel.org
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1470939463-31950-2-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: dhowells@redhat.com
Cc: linux-arch@vger.kernel.org
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1470939463-31950-1-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
17 Jun, 2016
1 commit
-
Nothing in the control-dependencies section of memory-barriers.txt
says that control dependencies don't extend beyond the end of the
if-statement containing the control dependency. Worse yet, in many
situations, they do extend beyond that if-statement. In particular,
the compiler cannot destroy the control dependency given proper use of
READ_ONCE() and WRITE_ONCE(). However, a weakly ordered system having
a conditional-move instruction provides the control-dependency guarantee
only to code within the scope of the if-statement itself.This commit therefore adds words and an example demonstrating this
limitation of control dependencies.Reported-by: Will Deacon
Signed-off-by: Paul E. McKenney
Acked-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: corbet@lwn.net
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20160615230817.GA18039@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
28 Apr, 2016
3 commits
-
For compound atomics performing both a load and a store operation, make
it clear that _acquire and _release variants refer only to the load and
store portions of compound atomic. For example, xchg_acquire is an xchg
operation where the load takes on ACQUIRE semantics.Signed-off-by: Will Deacon
Signed-off-by: Paul E. McKenney
Acked-by: Peter Zijlstra (Intel)
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: corbet@lwn.net
Cc: dave@stgolabs.net
Cc: dhowells@redhat.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1461691328-5429-3-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
There has been some confusion about the purpose of memory-barriers.txt,
so this commit adds a statement of purpose.Signed-off-by: David Howells
Signed-off-by: Paul E. McKenney
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: corbet@lwn.net
Cc: dave@stgolabs.net
Cc: linux-doc@vger.kernel.org
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1461691328-5429-2-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
It appears people are reading this document as a requirements list for
building hardware. This is not the intent of this document. Nor is it
particularly suited for this purpose.The primary purpose of this document is our collective attempt to define
a set of primitives that (hopefully) allow us to write correct code on
the myriad of SMP platforms Linux supports.Its a definite work in progress as our understanding of these platforms,
and memory ordering in general, progresses.Nor does being mentioned in this document mean we think its a
particularly good idea; the data dependency barrier required by Alpha
being a prime example. Yes we have it, no you're insane to require it
when building new hardware.Signed-off-by: Peter Zijlstra (Intel)
Signed-off-by: Paul E. McKenney
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: corbet@lwn.net
Cc: dave@stgolabs.net
Cc: dhowells@redhat.com
Cc: linux-doc@vger.kernel.org
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1461691328-5429-1-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar
13 Apr, 2016
4 commits
-
... do this next to smp_load_acquire() when first mentioning
ACQUIRE. While this call is briefly explained and control
dependencies are mentioned later, it does not hurt the reader.Signed-off-by: Davidlohr Bueso
Signed-off-by: Paul E. McKenney
Cc: Andrew Morton
Cc: Davidlohr Bueso
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: bobby.prani@gmail.com
Cc: dhowells@redhat.com
Cc: dipankar@in.ibm.com
Cc: dvhart@linux.intel.com
Cc: edumazet@google.com
Cc: fweisbec@gmail.com
Cc: jiangshanlai@gmail.com
Cc: josh@joshtriplett.org
Cc: mathieu.desnoyers@efficios.com
Cc: oleg@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1460476375-27803-7-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
The document uses two newlines between sections, one newline between
item and its detailed description, and two spaces between sentences.There are a few places that used these rules inconsistently - fix them.
Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Acked-by: David Howells
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: bobby.prani@gmail.com
Cc: dipankar@in.ibm.com
Cc: dvhart@linux.intel.com
Cc: edumazet@google.com
Cc: fweisbec@gmail.com
Cc: jiangshanlai@gmail.com
Cc: josh@joshtriplett.org
Cc: mathieu.desnoyers@efficios.com
Cc: oleg@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1460476375-27803-5-git-send-email-paulmck@linux.vnet.ibm.com
[ Fixed the changelog. ]
Signed-off-by: Ingo Molnar -
Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Acked-by: David Howells
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: bobby.prani@gmail.com
Cc: dipankar@in.ibm.com
Cc: dvhart@linux.intel.com
Cc: edumazet@google.com
Cc: fweisbec@gmail.com
Cc: jiangshanlai@gmail.com
Cc: josh@joshtriplett.org
Cc: mathieu.desnoyers@efficios.com
Cc: oleg@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1460476375-27803-4-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar -
A 'Virtual Machine Guests' subsection was added by this commit:
6a65d26385bf487 ("asm-generic: implement virt_xxx memory barriers")
but the TOC was not updated - update it.
Signed-off-by: SeongJae Park
Signed-off-by: Paul E. McKenney
Acked-by: David Howells
Cc: Andrew Morton
Cc: Linus Torvalds
Cc: Peter Zijlstra
Cc: Thomas Gleixner
Cc: bobby.prani@gmail.com
Cc: dipankar@in.ibm.com
Cc: dvhart@linux.intel.com
Cc: edumazet@google.com
Cc: fweisbec@gmail.com
Cc: jiangshanlai@gmail.com
Cc: josh@joshtriplett.org
Cc: mathieu.desnoyers@efficios.com
Cc: oleg@redhat.com
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/1460476375-27803-3-git-send-email-paulmck@linux.vnet.ibm.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar
