linux-toradex.git/include/linux/spinlock.h, branch v4.14-rc7

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2017-09-04T18:52:29+00:00

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
  ...

locking: Remove spin_unlock_wait() generic definitions

2017-08-17T15:08:58+00:00

There is no agreed-upon definition of spin_unlock_wait()'s semantics,
and it appears that all callers could do just as well with a lock/unlock
pair.  This commit therefore removes spin_unlock_wait() and related
definitions from core code.

Signed-off-by: Paul E. McKenney 
Cc: Arnd Bergmann 
Cc: Ingo Molnar 
Cc: Will Deacon 
Cc: Peter Zijlstra 
Cc: Alan Stern 
Cc: Andrea Parri 
Cc: Linus Torvalds

locking: Remove smp_mb__before_spinlock()

2017-08-10T10:29:03+00:00

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

locking: Introduce smp_mb__after_spinlock()

2017-08-10T10:29:02+00:00

Since its inception, our understanding of ACQUIRE, esp. as applied to
spinlocks, has changed somewhat. Also, I wonder if, with a simple
change, we cannot make it provide more.

The problem with the comment is that the STORE done by spin_lock isn't
itself ordered by the ACQUIRE, and therefore a later LOAD can pass over
it and cross with any prior STORE, rendering the default WMB
insufficient (pointed out by Alan).

Now, this is only really a problem on PowerPC and ARM64, both of
which already defined smp_mb__before_spinlock() as a smp_mb().

At the same time, we can get a much stronger construct if we place
that same barrier _inside_ the spin_lock(). In that case we upgrade
the RCpc spinlock to an RCsc.  That would make all schedule() calls
fully transitive against one another.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Will Deacon 
Cc: Alan Stern 
Cc: Benjamin Herrenschmidt 
Cc: Linus Torvalds 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Oleg Nesterov 
Cc: Paul McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar

atomics: Revert addition of comment header to spin_unlock_wait()

2017-07-25T16:59:08+00:00

There is still considerable confusion as to the semantics of
spin_unlock_wait(), but there seems to be universal agreement that
it is not that of a lock/unlock pair.  This commit therefore removes
the comment added by 6016ffc3874d ("atomics: Add header comment so
spin_unlock_wait()") in order to prevent at least that flavor of
confusion.

Signed-off-by: Paul E. McKenney

atomics: Add header comment so spin_unlock_wait()

2017-06-08T15:25:29+00:00

There is material describing the ordering guarantees provided by
spin_unlock_wait(), but it is not necessarily easy to find.  This commit
therefore adds a docbook header comment to this function informally
describing its semantics.

Signed-off-by: Paul E. McKenney 
Acked-by: Peter Zijlstra

locking/spinlocks: Remove the unused spin_lock_bh_nested() API

2017-01-12T08:33:39+00:00

The spin_lock_bh_nested() API is defined but is not used anywhere
in the kernel. So all spin_lock_bh_nested() and related APIs are
now removed.

Signed-off-by: Waiman Long 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1483975612-16447-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-09-01T15:40:25+00:00

Pull x86 asm changes from Ingo Molnar:
 "The biggest changes in this cycle were:

   - Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC)
     primitives.  (Andy Lutomirski)

   - Add new, comprehensible entry and exit handlers written in C.
     (Andy Lutomirski)

   - vm86 mode cleanups and fixes.  (Brian Gerst)

   - 32-bit compat code cleanups.  (Brian Gerst)

  The amount of simplification in low level assembly code is already
  palpable:

     arch/x86/entry/entry_32.S                          | 130 +----
     arch/x86/entry/entry_64.S                          | 197 ++-----

  but more simplifications are planned.

  There's also the usual laudry mix of low level changes - see the
  changelog for details"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits)
  x86/asm: Drop repeated macro of X86_EFLAGS_AC definition
  x86/asm/msr: Make wrmsrl() a function
  x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer
  x86/asm: Add MONITORX/MWAITX instruction support
  x86/traps: Weaken context tracking entry assertions
  x86/asm/tsc: Add rdtscll() merge helper
  selftests/x86: Add syscall_nt selftest
  selftests/x86: Disable sigreturn_64
  x86/vdso: Emit a GNU hash
  x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
  x86/entry/32: Migrate to C exit path
  x86/entry/32: Remove 32-bit syscall audit optimizations
  x86/vm86: Rename vm86->v86flags and v86mask
  x86/vm86: Rename vm86->vm86_info to user_vm86
  x86/vm86: Clean up vm86.h includes
  x86/vm86: Move the vm86 IRQ definitions to vm86.h
  x86/vm86: Use the normal pt_regs area for vm86
  x86/vm86: Eliminate 'struct kernel_vm86_struct'
  x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
  x86/vm86: Move vm86 fields out of 'thread_struct'
  ...

rcu,locking: Privatize smp_mb__after_unlock_lock()

2015-08-04T15:49:21+00:00

RCU is the only thing that uses smp_mb__after_unlock_lock(), and is
likely the only thing that ever will use it, so this commit makes this
macro private to RCU.

Signed-off-by: Paul E. McKenney 
Cc: Will Deacon 
Cc: Peter Zijlstra 
Cc: Benjamin Herrenschmidt 
Cc: "linux-arch@vger.kernel.org"

locking/spinlocks: Force inlining of spinlock ops

2015-07-21T08:14:07+00:00

With both gcc 4.7.2 and 4.9.2, sometimes GCC mysteriously
doesn't inline very small functions we expect to be inlined.
See:

    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122

In particular, with this config:

   http://busybox.net/~vda/kernel_config

there are more than a thousand copies of tiny spinlock-related
functions:

  $ nm --size-sort vmlinux | grep -iF ' t ' | uniq -c | grep -v '^ *1 ' | sort -rn | grep ' spin'
    473 000000000000000b t spin_unlock_irqrestore
    292 000000000000000b t spin_unlock
    215 000000000000000b t spin_lock
    134 000000000000000b t spin_unlock_irq
    130 000000000000000b t spin_unlock_bh
    120 000000000000000b t spin_lock_irq
    106 000000000000000b t spin_lock_bh

Disassembly:

 ffffffff81004720 :
 ffffffff81004720:       55                      push   %rbp
 ffffffff81004721:       48 89 e5                mov    %rsp,%rbp
 ffffffff81004724:       e8 f8 4e e2 02          callq <_raw_spin_lock>
 ffffffff81004729:       5d                      pop    %rbp
 ffffffff8100472a:       c3                      retq

This patch fixes this via s/inline/__always_inline/ in
spinlock.h. This decreases vmlinux by about 40k:

      text     data      bss       dec     hex filename
  82375570 22255544 20627456 125258570 7774b4a vmlinux.before
  82335059 22255416 20627456 125217931 776ac8b vmlinux

Signed-off-by: Denys Vlasenko 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Bart Van Assche 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: David Rientjes 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Thomas Graf 
Link: http://lkml.kernel.org/r/1436812263-15243-1-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar