linux-toradex.git/include/asm-generic/bitops, branch v4.6-rc3

bitops: Do not default to __clear_bit() for __clear_bit_unlock()

2016-03-21T09:50:48+00:00

__clear_bit_unlock() is a special little snowflake. While it carries the
non-atomic '__' prefix, it is specifically documented to pair with
test_and_set_bit() and therefore should be 'somewhat' atomic.

Therefore the generic implementation of __clear_bit_unlock() cannot use
the fully non-atomic __clear_bit() as a default.

If an arch is able to do better; is must provide an implementation of
__clear_bit_unlock() itself.

Specifically, this came up as a result of hackbench livelock'ing in
slab_lock() on ARC with SMP + SLUB + !LLSC.

The issue was incorrect pairing of atomic ops.

 slab_lock() -> bit_spin_lock() -> test_and_set_bit()
 slab_unlock() -> __bit_spin_unlock() -> __clear_bit()

The non serializing __clear_bit() was getting "lost"

 80543b8e:	ld_s       r2,[r13,0] <--- (A) Finds PG_locked is set
 80543b90:	or         r3,r2,1    <--- (B) other core unlocks right here
 80543b94:	st_s       r3,[r13,0] <--- (C) sets PG_locked (overwrites unlock)

Fixes ARC STAR 9000817404 (and probably more).

Reported-by: Vineet Gupta 
Tested-by: Vineet Gupta 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Christoph Lameter 
Cc: David Rientjes 
Cc: Helge Deller 
Cc: James E.J. Bottomley 
Cc: Joonsoo Kim 
Cc: Linus Torvalds 
Cc: Noam Camus 
Cc: Paul E. McKenney 
Cc: Pekka Enberg 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160309114054.GJ6356@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar

move count_zeroes.h out of asm-generic

2015-10-14T22:21:07+00:00

This header contains a few helpers currenly only used by the mpi
implementation, and not default implementation of architecture code.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Arnd Bergmann

arch: Mass conversion of smp_mb__*()

2014-04-18T12:20:48+00:00

Mostly scripted conversion of the smp_mb__* barriers.

Signed-off-by: Peter Zijlstra 
Acked-by: Paul E. McKenney 
Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org
Cc: Linus Torvalds 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Ingo Molnar

bitops: Fix signedness of compile-time hweight implementations

2014-02-09T12:39:26+00:00

Enabling '-Wsign-compare' compiler warnings on code that includes
include/linux/bitops.h can generate the following warning:

  In file included from include/linux/kernel.h:10:0,
                    from :48:
  include/linux/bitops.h: In function 'hweight_long':
  include/linux/bitops.h:77:26: error: signed and unsigned type in conditional expression [-Werror=sign-compare]

(converted to an error with -Werror)

This is due to the use of the logical negation operator '!' in the
__const_hweight8 macro in include/asm-generic/bitops/const_hweight.h.
The use of that operator here results in a signed value.

Fix by explicitly casting the __const_hweight8 macro expansion to
'unsigned int'.  While here, clean up several checkpatch.pl warnings.

Signed-off-by: Paul Walmsley 
Cc: Arnd Bergmann 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1312180459580.30198@tamien
Signed-off-by: Ingo Molnar

bitops/find: clarify and extend documentation

2013-11-13T03:09:22+00:00

Add return value documentation and clarify the units of the @size
parameter.

Signed-off-by: Cody P Schafer 
Cc: Arnd Bergmann 
Cc: Cody P Schafer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2012-10-14T20:39:34+00:00

Pull module signing support from Rusty Russell:
 "module signing is the highlight, but it's an all-over David Howells frenzy..."

Hmm "Magrathea: Glacier signing key". Somebody has been reading too much HHGTTG.

* 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (37 commits)
  X.509: Fix indefinite length element skip error handling
  X.509: Convert some printk calls to pr_devel
  asymmetric keys: fix printk format warning
  MODSIGN: Fix 32-bit overflow in X.509 certificate validity date checking
  MODSIGN: Make mrproper should remove generated files.
  MODSIGN: Use utf8 strings in signer's name in autogenerated X.509 certs
  MODSIGN: Use the same digest for the autogen key sig as for the module sig
  MODSIGN: Sign modules during the build process
  MODSIGN: Provide a script for generating a key ID from an X.509 cert
  MODSIGN: Implement module signature checking
  MODSIGN: Provide module signing public keys to the kernel
  MODSIGN: Automatically generate module signing keys if missing
  MODSIGN: Provide Kconfig options
  MODSIGN: Provide gitignore and make clean rules for extra files
  MODSIGN: Add FIPS policy
  module: signature checking hook
  X.509: Add a crypto key parser for binary (DER) X.509 certificates
  MPILIB: Provide a function to read raw data into an MPI
  X.509: Add an ASN.1 decoder
  X.509: Add simple ASN.1 grammar compiler
  ...

MPILIB: Provide count_leading/trailing_zeros() based on arch functions

2012-10-08T03:20:11+00:00

Provide count_leading/trailing_zeros() macros based on extant arch bit scanning
functions rather than reimplementing from scratch in MPILIB.

Whilst we're at it, turn count_foo_zeros(n, x) into n = count_foo_zeros(x).

Also move the definition to asm-generic as other people may be interested in
using it.

Signed-off-by: David Howells 
Cc: David S. Miller 
Cc: Dmitry Kasatkin 
Cc: Arnd Bergmann 
Signed-off-by: Rusty Russell

bitops: introduce generic {clear,set}_bit_le()

2012-10-05T18:04:55+00:00

Needed to replace test_and_set_bit_le() in virt/kvm/kvm_main.c which is
being used for this missing function.

Signed-off-by: Takuya Yoshikawa 
Acked-by: Arnd Bergmann 
Cc: Marcelo Tosatti 
Cc: Avi Kivity 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

generic: Implement generic ffs/fls using __builtin_* functions

2012-09-14T16:15:41+00:00

This patch implements ffs, __ffs, fls, __fls using __builtin_* gcc
functions. These header files can be used by other architectures that
rely on the gcc builtins.

Signed-off-by: Catalin Marinas 
Acked-by: Arnd Bergmann

Add #includes needed to permit the removal of asm/system.h

2012-03-28T17:30:03+00:00

asm/system.h is a cause of circular dependency problems because it contains
commonly used primitive stuff like barrier definitions and uncommonly used
stuff like switch_to() that might require MMU definitions.

asm/system.h has been disintegrated by this point on all arches into the
following common segments:

 (1) asm/barrier.h

     Moved memory barrier definitions here.

 (2) asm/cmpxchg.h

     Moved xchg() and cmpxchg() here.  #included in asm/atomic.h.

 (3) asm/bug.h

     Moved die() and similar here.

 (4) asm/exec.h

     Moved arch_align_stack() here.

 (5) asm/elf.h

     Moved AT_VECTOR_SIZE_ARCH here.

 (6) asm/switch_to.h

     Moved switch_to() here.

Signed-off-by: David Howells