Commit Graph

41 Commits

Author SHA1 Message Date
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00
Mark Rutland e88d62cd4b percpu: make this_cpu_generic_read() atomic w.r.t. interrupts
As raw_cpu_generic_read() is a plain read from a raw_cpu_ptr() address,
it's possible (albeit unlikely) that the compiler will split the access
across multiple instructions.

In this_cpu_generic_read() we disable preemption but not interrupts
before calling raw_cpu_generic_read(). Thus, an interrupt could be taken
in the middle of the split load instructions. If a this_cpu_write() or
RMW this_cpu_*() op is made to the same variable in the interrupt
handling path, this_cpu_read() will return a torn value.

For native word types, we can avoid tearing using READ_ONCE(), but this
won't work in all cases (e.g. 64-bit types on most 32-bit platforms).
This patch reworks this_cpu_generic_read() to use READ_ONCE() where
possible, otherwise falling back to disabling interrupts.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-09-26 07:37:33 -07:00
Heiko Carstens 7f8d61f005 percpu: use notrace variant of preempt_disable/preempt_enable
Commit 345ddcc882 ("ftrace: Have set_ftrace_pid use the bitmap like
events do") added a couple of this_cpu_read calls to the ftrace code.

On x86 this is not a problem, since it has single instructions to read
percpu data. Other architectures which use the generic variant now
have additional preempt_disable and preempt_enable calls in the core
ftrace code. This may lead to recursive calls and in result to a dead
machine, e.g. if preemption and debugging options are enabled.

To fix this use the notrace variant of preempt_disable and
preempt_enable within the generic percpu code.

Reported-and-bisected-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Tested-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Fixes: 345ddcc882 ("ftrace: Have set_ftrace_pid use the bitmap like events do")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2016-11-08 10:29:44 +01:00
Nicholas Piggin 1b5ca12127 percpu: improve generic percpu modify-return implementation
Some architectures require an additional load to find the address of
percpu pointers. In some implemenatations, the C aliasing rules do not
allow the result of that load to be kept over the store that modifies
the percpu variable, which causes additional loads.

Work around this by finding the pointer first, then operating on that.

It's also possible to mark things as restrict and those kind of games,
but that can require larger and arch specific changes.

On powerpc, __this_cpu_inc_return compiles to:

        ld 10,48(13)
        ldx 9,3,10
        addi 9,9,1
        stdx 9,3,10
        ld 9,48(13)
        ldx 3,9,3

With this patch it compiles to:

        ld 10,48(13)
        ldx 9,3,10
        addi 9,9,1
        stdx 9,3,10

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
To: Tejun Heo <tj@kernel.org>
To: Christoph Lameter <cl@linux.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
2016-09-22 12:06:53 -04:00
Tejun Heo eba117889a percpu: preffity percpu header files
percpu macros are difficult to read.  It's partly because they're
fairly complex but also because they simply lack visual and
conventional consistency to an unusual degree.  The preceding patches
tried to organize macro definitions consistently by their roles.  This
patch makes the following cosmetic changes to improve overall
readability.

* Use consistent convention for multi-line macro definitions - "do {"
  or "({" are now put on their own lines and the line continuing '\'
  are all put on the same column.

* Temp variables used inside macro are consistently given "__" prefix.

* When a macro argument is passed to another macro or a function,
  putting extra parenthses around it doesn't help anything.  Don't put
  them.

* _this_cpu_generic_*() are renamed to this_cpu_generic_*() so that
  they're consistent with raw_cpu_generic_*().

* Reorganize raw_cpu_*() and this_cpu_*() definitions so that trivial
  wrappers are collected in one place after actual operation
  definitions.

* Other misc cleanups including reorganizing comments.

All changes in this patch are cosmetic and cause no functional
difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
2014-06-17 19:12:40 -04:00
Tejun Heo 9c28278a24 percpu: reorder macros in percpu header files
* In include/asm-generic/percpu.h, collect {raw|_this}_cpu_generic*()
  macros into one place.  They were dispersed through
  {raw|this}_cpu_*_N() definitions and the visiual inconsistency was
  making following the code unnecessarily difficult.

* In include/linux/percpu-defs.h, move __verify_pcpu_ptr() later in
  the file so that it's right above accessor definitions where it's
  actually used.

This is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
2014-06-17 19:12:39 -04:00
Tejun Heo 47b69ad673 percpu: move generic {raw|this}_cpu_*_N() definitions to include/asm-generic/percpu.h
{raw|this}_cpu_*_N() operations are expected to be provided by archs
and the generic definitions are provided as fallbacks.  As such, these
firmly belong to include/asm-generic/percpu.h.

Move the generic definitions to include/asm-generic/percpu.h.  The
code is moved mostly verbatim; however, raw_cpu_*_N() are placed above
this_cpu_*_N() which is more conventional as the raw operations may be
used to defined other variants.

This is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
2014-06-17 19:12:39 -04:00
Tejun Heo 62fde54123 percpu: include/asm-generic/percpu.h should contain only arch-overridable parts
The roles of the various percpu header files has become unclear.
There are four header files involved.

 include/linux/percpu-defs.h
 include/linux/percpu.h
 include/asm-generic/percpu.h
 arch/*/include/asm/percpu.h

The original intention for include/asm-generic/percpu.h is providing
generic definitions for arch-overridable parts; however, it now hosts
various stuff which can't be overridden by archs.

Also, include/linux/percpu-defs.h was initially added to contain
section and percpu variable definition macros so that arch header
files can make use of them without worrying about introducing cyclic
inclusion dependency by including include/linux/percpu.h; however,
arch headers sometimes need to access percpu variables too and this is
one of the reasons why some accessors were implemented in
include/linux/asm-generic/percpu.h.

Let's clear up the situation by making include/asm-generic/percpu.h
contain only arch-overridable parts and moving accessors and
operations into include/linux/percpu-defs.  Note that this patch only
moves things from include/asm-generic/percpu.h.
include/linux/percpu.h will be taken care of by later patches.

This patch moves the followings.

* SHIFT_PERCPU_PTR() / VERIFY_PERCPU_PTR()
* per_cpu()
* raw_cpu_ptr()
* this_cpu_ptr()
* __get_cpu_var()
* __raw_get_cpu_var()
* __this_cpu_ptr()
* PER_CPU_[SHARED_]ALIGNED_SECTION
* PER_CPU_[SHARED_]ALIGNED_SECTION
* PER_CPU_FIRST_SECTION

This patch is pure reorganization.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
2014-06-17 19:12:34 -04:00
Tejun Heo bbc344e1e3 percpu: introduce arch_raw_cpu_ptr()
Currently, archs can override raw_cpu_ptr() directly; however, we
wanna build a layer of indirection in the generic part of percpu so
that we can implement generic features there without affecting archs.

Introduce arch_raw_cpu_ptr() which is used to define raw_cpu_ptr() by
generic percpu code.  The two are identical for now.  x86 is currently
the only arch which overrides raw_cpu_ptr() and is converted to
define arch_raw_cpu_ptr() instead.

This doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
2014-06-17 19:12:34 -04:00
Tejun Heo 6adc5cac53 percpu: disallow archs from overriding SHIFT_PERCPU_PTR()
It has been about half a decade since all archs started using the
dynamic percpu allocator and thus the same SHIFT_PERCPU_PTR()
implementation.  There's no benefit in overriding SHIFT_PERCPU_PTR()
anymore.

Remove #ifndef around it to clarify that this is identical regardless
of the arch.

This patch doesn't cause any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
2014-06-17 19:12:33 -04:00
Christoph Lameter b3ca1c10d7 percpu: add raw_cpu_ops
The kernel has never been audited to ensure that this_cpu operations are
consistently used throughout the kernel.  The code generated in many
places can be improved through the use of this_cpu operations (which
uses a segment register for relocation of per cpu offsets instead of
performing address calculations).

The patch set also addresses various consistency issues in general with
the per cpu macros.

A. The semantics of __this_cpu_ptr() differs from this_cpu_ptr only
   because checks are skipped. This is typically shown through a raw_
   prefix. So this patch set changes the places where __this_cpu_ptr()
   is used to raw_cpu_ptr().

B. There has been the long term wish by some that __this_cpu operations
   would check for preemption. However, there are cases where preemption
   checks need to be skipped. This patch set adds raw_cpu operations that
   do not check for preemption and then adds preemption checks to the
   __this_cpu operations.

C. The use of __get_cpu_var is always a reference to a percpu variable
   that can also be handled via a this_cpu operation. This patch set
   replaces all uses of __get_cpu_var with this_cpu operations.

D. We can then use this_cpu RMW operations in various places replacing
   sequences of instructions by a single one.

E. The use of this_cpu operations throughout will allow other arches than
   x86 to implement optimized references and RMV operations to work with
   per cpu local data.

F. The use of this_cpu operations opens up the possibility to
   further optimize code that relies on synchronization through
   per cpu data.

The patch set works in a couple of stages:

I. Patch 1 adds the additional raw_cpu operations and raw_cpu_ptr().
    Also converts the existing __this_cpu_xx_# primitive in the x86
    code to raw_cpu_xx_#.

II. Patch 2-4 use the raw_cpu operations in places that would give
     us false positives once they are enabled.

III. Patch 5 adds preemption checks to __this_cpu operations to allow
    checking if preemption is properly disabled when these functions
    are used.

IV. Patches 6-20 are patches that simply replace uses of __get_cpu_var
   with this_cpu_ptr. They do not depend on any changes to the percpu
   code. No preemption tests are skipped if they are applied.

V. Patches 21-46 are conversion patches that use this_cpu operations
   in various kernel subsystems/drivers or arch code.

VI.  Patches 47/48 (not included in this series) remove no longer used
    functions (__this_cpu_ptr and __get_cpu_var).  These should only be
    applied after all the conversion patches have made it and after we
    have done additional passes through the kernel to ensure that none of
    the uses of these functions remain.

This patch (of 46):

The patches following this one will add preemption checks to __this_cpu
ops so we need to have an alternative way to use this_cpu operations
without preemption checks.

raw_cpu_ops will be the basis for all other ops since these will be the
operations that do not implement any checks.

Primitive operations are renamed by this patch from __this_cpu_xxx to
raw_cpu_xxxx.

Also change the uses of the x86 percpu primitives in preempt.h.
These depend directly on asm/percpu.h (header #include nesting issue).

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: David Daney <david.daney@cavium.com>
Cc: David Miller <davem@davemloft.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Hedi Berriche <hedi@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Robert Richter <rric@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:13 -07:00
Brian Gerst 677243d749 percpu: Optimize __get_cpu_var()
Redefine __get_cpu_var() using this_cpu_ptr() which can be
arch-optimized.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-09-10 10:56:51 +02:00
Brian Gerst db7829c6cc x86, percpu: Optimize this_cpu_ptr
Allow arches to implement __this_cpu_ptr, and provide an x86 version.

Before:
	movq $foo, %rax
	movq %gs:this_cpu_off, %rdx
	addq %rdx, %rax

After:
	movq $foo, %rax
	addq %gs:this_cpu_off, %rax

The benefit is doing it in one less instruction and not clobbering
a temporary register.

tj: * Beefed up the comment a bit and renamed in-macro temp variable
      to match neighboring macros.

    * Folded fix for const pointer case found in linux-next.

    * Fixed sparse notation.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-09-10 10:56:47 +02:00
Namhyung Kim 18cb2aef91 percpu: handle __percpu notations in UP accessors
UP accessors didn't take care of __percpu notations leading to a lot
of spurious sparse warnings on UP configurations.  Fix it.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2010-08-07 14:20:53 +02:00
Linus Torvalds 1f73897861 Merge branch 'for-35' of git://repo.or.cz/linux-kbuild
* 'for-35' of git://repo.or.cz/linux-kbuild: (81 commits)
  kbuild: Revert part of e8d400a to resolve a conflict
  kbuild: Fix checking of scm-identifier variable
  gconfig: add support to show hidden options that have prompts
  menuconfig: add support to show hidden options which have prompts
  gconfig: remove show_debug option
  gconfig: remove dbg_print_ptype() and dbg_print_stype()
  kconfig: fix zconfdump()
  kconfig: some small fixes
  add random binaries to .gitignore
  kbuild: Include gen_initramfs_list.sh and the file list in the .d file
  kconfig: recalc symbol value before showing search results
  .gitignore: ignore *.lzo files
  headerdep: perlcritic warning
  scripts/Makefile.lib: Align the output of LZO
  kbuild: Generate modules.builtin in make modules_install
  Revert "kbuild: specify absolute paths for cscope"
  kbuild: Do not unnecessarily regenerate modules.builtin
  headers_install: use local file handles
  headers_check: fix perl warnings
  export_report: fix perl warnings
  ...
2010-06-01 08:55:52 -07:00
Denys Vlasenko 3d9a854c2d Rename .data[.percpu][.XXX] to .data[..percpu][..XXX].
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
2010-03-03 11:26:00 +01:00
Tejun Heo 545695fb41 percpu: make accessors check for percpu pointer in sparse
The previous patch made sparse warn about percpu variables being used
directly without going through percpu accessors.  This patch
implements the other half - checking whether non percpu variable is
passed into percpu accessors.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
2009-10-29 22:34:15 +09:00
Rusty Russell e0fdb0e050 percpu: add __percpu for sparse.
We have to make __kernel "__attribute__((address_space(0)))" so we can
cast to it.

tj: * put_cpu_var() update.

    * Annotations added to dynamic allocator interface.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
2009-10-29 22:34:15 +09:00
Rusty Russell dd17c8f729 percpu: remove per_cpu__ prefix.
Now that the return from alloc_percpu is compatible with the address
of per-cpu vars, it makes sense to hand around the address of per-cpu
variables.  To make this sane, we remove the per_cpu__ prefix we used
created to stop people accidentally using these vars directly.

Now we have sparse, we can use that (next patch).

tj: * Updated to convert stuff which were missed by or added after the
      original patch.

    * Kill per_cpu_var() macro.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
2009-10-29 22:34:15 +09:00
Christoph Lameter 7340a0b152 this_cpu: Introduce this_cpu_ptr() and generic this_cpu_* operations
This patch introduces two things: First this_cpu_ptr and then per cpu
atomic operations.

this_cpu_ptr
------------

A common operation when dealing with cpu data is to get the instance of the
cpu data associated with the currently executing processor. This can be
optimized by

this_cpu_ptr(xx) = per_cpu_ptr(xx, smp_processor_id).

The problem with per_cpu_ptr(x, smp_processor_id) is that it requires
an array lookup to find the offset for the cpu. Processors typically
have the offset for the current cpu area in some kind of (arch dependent)
efficiently accessible register or memory location.

We can use that instead of doing the array lookup to speed up the
determination of the address of the percpu variable. This is particularly
significant because these lookups occur in performance critical paths
of the core kernel. this_cpu_ptr() can avoid memory accesses and

this_cpu_ptr comes in two flavors. The preemption context matters since we
are referring the the currently executing processor. In many cases we must
insure that the processor does not change while a code segment is executed.

__this_cpu_ptr 	-> Do not check for preemption context
this_cpu_ptr	-> Check preemption context

The parameter to these operations is a per cpu pointer. This can be the
address of a statically defined per cpu variable (&per_cpu_var(xxx)) or
the address of a per cpu variable allocated with the per cpu allocator.

per cpu atomic operations: this_cpu_*(var, val)
-----------------------------------------------
this_cpu_* operations (like this_cpu_add(struct->y, value) operate on
abitrary scalars that are members of structures allocated with the new
per cpu allocator. They can also operate on static per_cpu variables
if they are passed to per_cpu_var() (See patch to use this_cpu_*
operations for vm statistics).

These operations are guaranteed to be atomic vs preemption when modifying
the scalar. The calculation of the per cpu offset is also guaranteed to
be atomic at the same time. This means that a this_cpu_* operation can be
safely used to modify a per cpu variable in a context where interrupts are
enabled and preemption is allowed. Many architectures can perform such
a per cpu atomic operation with a single instruction.

Note that the atomicity here is different from regular atomic operations.
Atomicity is only guaranteed for data accessed from the currently executing
processor. Modifications from other processors are still possible. There
must be other guarantees that the per cpu data is not modified from another
processor when using these instruction. The per cpu atomicity is created
by the fact that the processor either executes and instruction or not.
Embedded in the instruction is the relocation of the per cpu address to
the are reserved for the current processor and the RMW action. Therefore
interrupts or preemption cannot occur in the mids of this processing.

Generic fallback functions are used if an arch does not define optimized
this_cpu operations. The functions come also come in the two flavors used
for this_cpu_ptr().

The firstparameter is a scalar that is a member of a structure allocated
through allocpercpu or a per cpu variable (use per_cpu_var(xxx)). The
operations are similar to what percpu_add() and friends do.

this_cpu_read(scalar)
this_cpu_write(scalar, value)
this_cpu_add(scale, value)
this_cpu_sub(scalar, value)
this_cpu_inc(scalar)
this_cpu_dec(scalar)
this_cpu_and(scalar, value)
this_cpu_or(scalar, value)
this_cpu_xor(scalar, value)

Arch code can override the generic functions and provide optimized atomic
per cpu operations. These atomic operations must provide both the relocation
(x86 does it through a segment override) and the operation on the data in a
single instruction. Otherwise preempt needs to be disabled and there is no
gain from providing arch implementations.

A third variant is provided prefixed by irqsafe_. These variants are safe
against hardware interrupts on the *same* processor (all per cpu atomic
primitives are *always* *only* providing safety for code running on the
*same* processor!). The increment needs to be implemented by the hardware
in such a way that it is a single RMW instruction that is either processed
before or after an interrupt.

cc: David Howells <dhowells@redhat.com>
cc: Ingo Molnar <mingo@elte.hu>
cc: Rusty Russell <rusty@rustcorp.com.au>
cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
2009-10-03 19:48:22 +09:00
Jeremy Fitzhardinge 53f824520b x86/i386: Put aligned stack-canary in percpu shared_aligned section
Pack aligned things together into a special section to minimize
padding holes.

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Tejun Heo <tj@kernel.org>
LKML-Reference: <4AA035C0.9070202@goop.org>
[ queued up in tip:x86/asm because it depends on this commit:
  x86/i386: Make sure stack-protector segment base is cache aligned ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-04 07:10:31 +02:00
Tejun Heo b01e8dc343 alpha: fix percpu build breakage
alpha percpu access requires custom SHIFT_PERCPU_PTR() definition for
modules to work around addressing range limitation.  This is done via
generating inline assembly using C preprocessing which forces the
assembler to generate external reference.  This happens behind the
compiler's back and makes the compiler think that static percpu variables
in modules are unused.

This used to be worked around by using __unused attribute for percpu
variables which prevent the compiler from omitting the variable; however,
recent declare/definition attribute unification change broke this as
__used can't be used for declaration.  Also, in the process,
PER_CPU_ATTRIBUTES definition in alpha percpu.h got broken.

This patch adds PER_CPU_DEF_ATTRIBUTES which is only used for definitions
and make alpha use it to add __used for percpu variables in modules.  This
also fixes the PER_CPU_ATTRIBUTES double definition bug.

Signed-off-by: Tejun Heo <tj@kernel.org>
Tested-by: maximilian attems <max@stro.at>
Acked-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Richard Henderson <rth@twiddle.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 18:55:59 -07:00
David Howells 5028eaa97d PERCPU: Collect the DECLARE/DEFINE declarations together
Collect the DECLARE/DEFINE declarations together in linux/percpu-defs.h so
that they're in one place, and give them descriptive comments, particularly
the SHARED_ALIGNED variant.

It would be nice to collect these in linux/percpu.h, but that's not possible
without sorting out the severe #include recursion between the x86 arch headers
and the general headers (and possibly other arches too).

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-21 19:40:00 -07:00
David Howells 9b8de7479d FRV: Fix the section attribute on UP DECLARE_PER_CPU()
In non-SMP mode, the variable section attribute specified by DECLARE_PER_CPU()
does not agree with that specified by DEFINE_PER_CPU().  This means that
architectures that have a small data section references relative to a base
register may throw up linkage errors due to too great a displacement between
where the base register points and the per-CPU variable.

On FRV, the .h declaration says that the variable is in the .sdata section, but
the .c definition says it's actually in the .data section.  The linker throws
up the following errors:

kernel/built-in.o: In function `release_task':
kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o
kernel/exit.c:78: relocation truncated to fit: R_FRV_GPREL12 against symbol `per_cpu__process_counts' defined in .data section in kernel/built-in.o

To fix this, DECLARE_PER_CPU() should simply apply the same section attribute
as does DEFINE_PER_CPU().  However, this is made slightly more complex by
virtue of the fact that there are several variants on DEFINE, so these need to
be matched by variants on DECLARE.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-21 19:39:59 -07:00
Tejun Heo 066123a535 percpu: unbreak alpha percpu
For the time being, move the generic percpu_*() accessors to
linux/percpu.h.

asm-generic/percpu.h is meant to carry generic stuff for low level
stuff - declarations, definitions and pointer offset calculation
and so on but not for generic interface.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-10 21:36:18 +02:00
Ingo Molnar 6dbde35308 percpu: add optimized generic percpu accessors
It is an optimization and a cleanup, and adds the following new
generic percpu methods:

  percpu_read()
  percpu_write()
  percpu_add()
  percpu_sub()
  percpu_and()
  percpu_or()
  percpu_xor()

and implements support for them on x86. (other architectures will fall
back to a default implementation)

The advantage is that for example to read a local percpu variable,
instead of this sequence:

 return __get_cpu_var(var);

 ffffffff8102ca2b:	48 8b 14 fd 80 09 74 	mov    -0x7e8bf680(,%rdi,8),%rdx
 ffffffff8102ca32:	81
 ffffffff8102ca33:	48 c7 c0 d8 59 00 00 	mov    $0x59d8,%rax
 ffffffff8102ca3a:	48 8b 04 10          	mov    (%rax,%rdx,1),%rax

We can get a single instruction by using the optimized variants:

 return percpu_read(var);

 ffffffff8102ca3f:	65 48 8b 05 91 8f fd 	mov    %gs:0x7efd8f91(%rip),%rax

I also cleaned up the x86-specific APIs and made the x86 code use
these new generic percpu primitives.

tj: * fixed generic percpu_sub() definition as Roel Kluin pointed out
    * added percpu_and() for completeness's sake
    * made generic percpu ops atomic against preemption

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-16 14:20:31 +01:00
Hugh Dickins 1e8352784a percpu: fix DEBUG_PREEMPT per_cpu checking
2.6.25-rc1 percpu changes broke CONFIG_DEBUG_PREEMPT's per_cpu checking
on several architectures.  On s390, sparc64 and x86 it's been weakened to
not checking at all; whereas on powerpc64 it's become too strict, issuing
warnings from __raw_get_cpu_var in io_schedule and init_timer for example.

Fix this by weakening powerpc's __my_cpu_offset to use the non-checking
local_paca instead of get_paca (which itself contains such a check);
and strengthening the generic my_cpu_offset to go the old slow way via
smp_processor_id when CONFIG_DEBUG_PREEMPT (debug_smp_processor_id is
where all the knowledge of what's correct when lives).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Reviewed-by: Mike Travis <travis@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-23 12:09:28 -08:00
Mike Travis dd5af90a7f x86/non-x86: percpu, node ids, apic ids x86.git fixup
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:33:32 +01:00
travis@sgi.com acdac87202 percpu: make the asm-generic/percpu.h more "generic"
- add support for PER_CPU_ATTRIBUTES

- fix generic smp percpu_modcopy to use per_cpu_offset() macro.

Add the ability to use generic/percpu even if the arch needs to override
several aspects of its operations. This will enable the use of generic
percpu.h for all arches.

An arch may define:

__per_cpu_offset	Do not use the generic pointer array. Arch must
			define per_cpu_offset(cpu) (used by x86_64, s390).

__my_cpu_offset		Can be defined to provide an optimized way to determine
			the offset for variables of the currently executing
			processor. Used by ia64, x86_64, x86_32, sparc64, s/390.

SHIFT_PTR(ptr, offset)	If an arch defines it then special handling
			of pointer arithmentic may be implemented. Used
			by s/390.

(Some of these special percpu arch implementations may be later consolidated
so that there are less cases to deal with.)

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:32:52 +01:00
travis@sgi.com 5280e004fc percpu: move arch XX_PER_CPU_XX definitions into linux/percpu.h
- Special consideration for IA64: Add the ability to specify
  arch specific per cpu flags

- remove .data.percpu attribute from DEFINE_PER_CPU for non-smp case.

The arch definitions are all the same. So move them into linux/percpu.h.

We cannot move DECLARE_PER_CPU since some include files just include
asm/percpu.h to avoid include recursion problems.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:32:52 +01:00
travis@sgi.com b32ef636a5 percpu: use a kconfig variable to signal arch specific percpu setup
The use of the __GENERIC_PERCPU is a bit problematic since arches
may want to run their own percpu setup while using the generic
percpu definitions. Replace it through a kconfig variable.

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-30 13:32:51 +01:00
Fenghua Yu 5fb7dc37dc define new percpu interface for shared data
per cpu data section contains two types of data.  One set which is
exclusively accessed by the local cpu and the other set which is per cpu,
but also shared by remote cpus.  In the current kernel, these two sets are
not clearely separated out.  This can potentially cause the same data
cacheline shared between the two sets of data, which will result in
unnecessary bouncing of the cacheline between cpus.

One way to fix the problem is to cacheline align the remotely accessed per
cpu data, both at the beginning and at the end.  Because of the padding at
both ends, this will likely cause some memory wastage and also the
interface to achieve this is not clean.

This patch:

Moves the remotely accessed per cpu data (which is currently marked
as ____cacheline_aligned_in_smp) into a different section, where all the data
elements are cacheline aligned. And as such, this differentiates the local
only data and remotely accessed data cleanly.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-19 10:04:44 -07:00
Rusty Russell ae1ee11be7 [PATCH] i386: Use per-cpu variables for GDT, PDA
Allocating PDA and GDT at boot is a pain.  Using simple per-cpu variables adds
happiness (although we need the GDT page-aligned for Xen, which we do in a
followup patch).

[akpm@linux-foundation.org: build fix]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2007-05-02 19:27:10 +02:00
Jan Blunck a666ecfbf5 [PATCH] Fix typo in "syntax error if percpu macros are incorrectly used" patch
Trivial typo fix in the "syntax error if percpu macros are incorrectly
used" patch.  I misspelled "identifier" in all places.  D'Oh!

Thanks to Dirk Mueller to point this out.

Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-06 08:53:41 -07:00
Jan Blunck 632bbfeee4 [PATCH] trigger a syntax error if percpu macros are incorrectly used
get_cpu_var()/per_cpu()/__get_cpu_var() arguments must be simple
identifiers.  Otherwise the arch dependent implementations might break.

This patch enforces the correct usage of the macros by producing a syntax
error if the variable is not a simple identifier.

Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26 08:48:44 -07:00
Ingo Molnar a875a69f8b [PATCH] lockdep: add per_cpu_offset()
Add the per_cpu_offset() generic method. (used by the lock validator)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03 15:27:00 -07:00
Paul Mackerras bfe5d83419 [PATCH] Define __raw_get_cpu_var and use it
There are several instances of per_cpu(foo, raw_smp_processor_id()), which
is semantically equivalent to __get_cpu_var(foo) but without the warning
that smp_processor_id() can give if CONFIG_DEBUG_PREEMPT is enabled.  For
those architectures with optimized per-cpu implementations, namely ia64,
powerpc, s390, sparc64 and x86_64, per_cpu() turns into more and slower
code than __get_cpu_var(), so it would be preferable to use __get_cpu_var
on those platforms.

This defines a __raw_get_cpu_var(x) macro which turns into per_cpu(x,
raw_smp_processor_id()) on architectures that use the generic per-cpu
implementation, and turns into __get_cpu_var(x) on the architectures that
have an optimized per-cpu implementation.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25 10:01:01 -07:00
KAMEZAWA Hiroyuki 0a94502277 [PATCH] for_each_possible_cpu: fixes for generic part
replaces for_each_cpu with for_each_possible_cpu().

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:16:05 -08:00
Andrew Morton 394e3902c5 [PATCH] more for_each_cpu() conversions
When we stop allocating percpu memory for not-possible CPUs we must not touch
the percpu data for not-possible CPUs at all.  The correct way of doing this
is to test cpu_possible() or to use for_each_cpu().

This patch is a kernel-wide sweep of all instances of NR_CPUS.  I found very
few instances of this bug, if any.  But the patch converts lots of open-coded
test to use the preferred helper macros.

Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Kyle McMartin <kyle@parisc-linux.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Christian Zankel <chris@zankel.net>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 07:38:17 -08:00
Jan Beulich 11c80c8367 [PATCH] adjust per_cpu definition in non-SMP case
Fix (in the architectures I'm actually building for) the UP definition of
per_cpu so that the cpu specified may be any expression, not just an
identifier or a suffix expression.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 09:45:28 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00