linux.git/lib/atomic64.c, branch v6.6.132

locking/atomic: atomic64: Remove unusable atomic ops

2021-12-13T09:56:09+00:00

The generic atomic64 implementation provides:

* atomic64_and_return()
* atomic64_or_return()
* atomic64_xor_return()

... but none of these exist in the standard atomic64 API as described by
scripts/atomic/atomics.tbl, and none of these have prototypes exposed by
.

The lkp kernel test robot noted this results in warnings when building with
W=1:

  lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_and_return' [-Wmissing-prototypes]

  lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_or_return' [-Wmissing-prototypes]

  lib/atomic64.c:82:5: warning: no previous prototype for 'generic_atomic64_xor_return' [-Wmissing-prototypes]

This appears to have been a thinko in commit:

  28aa2bda2211f432 ("locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()")

... where we grouped add/sub separately from and/ox/xor, so that we could avoid
implementing _return forms for the latter group, but forgot to remove
ATOMIC64_OP_RETURN() for that group.

This doesn't cause any functional problem, but it's pointless to build code
which cannot be used. Remove the unusable code. This does not affect add/sub,
for which _return forms will still be built.

Reported-by: kernel test robot 
Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Boqun Feng 
Link: https://lore.kernel.org/r/20211126115923.41489-1-mark.rutland@arm.com

locking/atomic: atomic64: support ARCH_ATOMIC

2021-05-26T11:20:50+00:00

We'd like all architectures to convert to ARCH_ATOMIC, as this will
enable functionality, and once all architectures are converted it will
be possible to make significant cleanups to the atomic headers.

A number of architectures use asm-generic/atomic64.h, and it's
impractical to convert the header and all these architectures in one go.
To make it possible to convert them one-by-one, let's make the
asm-generic implementation function as either atomic64_*() or
arch_atomic64_*() depending on whether ARCH_ATOMIC is selected. To do
this, the generic implementations are prefixed as generic_atomic64_*(),
and preprocessor definitions map atomic64_*()/arch_atomic64_*() onto
these as appropriate.

Once all users are moved over to ARCH_ATOMIC the ifdeffery in the header
can be simplified and/or removed entirely.

For existing users (none of which select ARCH_ATOMIC), there should be
no functional change as a result of this patch.

Signed-off-by: Mark Rutland 
Cc: Arnd Bergmann 
Cc: Boqun Feng 
Cc: Peter Zijlstra 
Cc: Will Deacon 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20210525140232.53872-11-mark.rutland@arm.com

locking/atomic: Use s64 for atomic64

2019-06-03T10:32:56+00:00

As a step towards making the atomic64 API use consistent types treewide,
let's have the generic atomic64 implementation use s64 as the underlying
type for atomic64_t, rather than long long, matching the generated
headers.

Otherwise, there should be no functional change as a result of this
patch.

Signed-off-by: Mark Rutland 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Arnd Bergmann 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: aou@eecs.berkeley.edu
Cc: bp@alien8.de
Cc: catalin.marinas@arm.com
Cc: davem@davemloft.net
Cc: fenghua.yu@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: ink@jurassic.park.msu.ru
Cc: jhogan@kernel.org
Cc: linux@armlinux.org.uk
Cc: mattst88@gmail.com
Cc: mpe@ellerman.id.au
Cc: palmer@sifive.com
Cc: paul.burton@mips.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: rth@twiddle.net
Cc: tony.luck@intel.com
Cc: vgupta@synopsys.com
Link: https://lkml.kernel.org/r/20190522132250.26499-4-mark.rutland@arm.com
Signed-off-by: Ingo Molnar

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

atomics/generic: Define atomic64_fetch_add_unless()

2018-06-21T12:25:21+00:00

As a step towards unifying the atomic/atomic64/atomic_long APIs, this
patch converts the generic implementation of atomic64_add_unless() into
a generic implementation of atomic64_fetch_add_unless().

A wrapper in  will build atomic_add_unless() atop of
this, provided it is given a preprocessor definition.

No functional change is intended as a result of this patch.

Signed-off-by: Mark Rutland 
Reviewed-by: Will Deacon 
Acked-by: Peter Zijlstra (Intel) 
Cc: Arnd Bergmann 
Cc: Boqun Feng 
Cc: Linus Torvalds 
Cc: Thomas Gleixner 
Link: https://lore.kernel.org/lkml/20180621121321.4761-9-mark.rutland@arm.com
Signed-off-by: Ingo Molnar

atomics: Make conditional ops return 'bool'

2018-06-21T12:22:33+00:00

Some of the atomics return a status value, which is a boolean value
describing whether the operation was performed. To make it clear that
this is a boolean value, let's update the common fallbacks to return
bool, fixing up the return values and comments likewise.

At the same time, let's simplify the description of the operations in
their respective comments.

The instrumented atomics and generic atomic64 implementation are updated
accordingly.

Note that atomic64_dec_if_positive() doesn't follow the usual test op
pattern, and returns the would-be decremented value. This is not
changed.

Signed-off-by: Mark Rutland 
Reviewed-by: Will Deacon 
Acked-by: Peter Zijlstra (Intel) 
Cc: Boqun Feng 
Cc: Linus Torvalds 
Cc: Michael Ellerman 
Cc: Thomas Gleixner 
Link: https://lore.kernel.org/lkml/20180621121321.4761-5-mark.rutland@arm.com
Signed-off-by: Ingo Molnar

locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()

2016-06-16T08:48:32+00:00

Now that all the architectures have implemented support for these new
atomic primitives add on the generic infrastructure to expose and use
it.

Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Arnd Bergmann 
Cc: Boqun Feng 
Cc: Borislav Petkov 
Cc: Davidlohr Bueso 
Cc: Frederic Weisbecker 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

atomic: Provide atomic_{or,xor,and}

2015-07-27T12:06:24+00:00

Implement atomic logic ops -- atomic_{or,xor,and}.

These will replace the atomic_{set,clear}_mask functions that are
available on some archs.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Thomas Gleixner

locking,arch: Rewrite generic atomic support

2014-08-14T10:48:14+00:00

Rewrite generic atomic support to only require cmpxchg(), generate all
other primitives from that.

Furthermore reduce the endless repetition for all these primitives to
a few CPP macros. This way we get more for less lines.

Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140508135852.940119622@infradead.org
Cc: Arnd Bergmann 
Cc: David Howells 
Cc: Paul E. McKenney 
Cc: David S. Miller 
Cc: Linus Torvalds 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar

lib: atomic64: Initialize locks statically to fix early users

2012-12-20T21:50:16+00:00

The atomic64 library uses a handful of static spin locks to implement
atomic 64-bit operations on architectures without support for atomic
64-bit instructions.

Unfortunately, the spinlocks are initialized in a pure initcall and that
is too late for the vfs namespace code which wants to use atomic64
operations before the initcall is run.

This became a problem as of commit 8823c079ba71: "vfs: Add setns support
for the mount namespace".

This leads to BUG messages such as:

  BUG: spinlock bad magic on CPU#0, swapper/0/0
   lock: atomic64_lock+0x240/0x400, .magic: 00000000, .owner: /-1, .owner_cpu: 0
    do_raw_spin_lock+0x158/0x198
    _raw_spin_lock_irqsave+0x4c/0x58
    atomic64_add_return+0x30/0x5c
    alloc_mnt_ns.clone.14+0x44/0xac
    create_mnt_ns+0xc/0x54
    mnt_init+0x120/0x1d4
    vfs_caches_init+0xe0/0x10c
    start_kernel+0x29c/0x300

coming out early on during boot when spinlock debugging is enabled.

Fix this by initializing the spinlocks statically at compile time.

Reported-and-tested-by: Vaibhav Bedia 
Tested-by: Tony Lindgren 
Cc: Eric W. Biederman 
Signed-off-by: Stephen Boyd 
Signed-off-by: Linus Torvalds