<feed xmlns='http://www.w3.org/2005/Atom'>
<title>lwn.git/arch/openrisc, branch docs-next-merge</title>
<subtitle>Linux kernel documentation tree maintained by Jonathan Corbet</subtitle>
<id>http://mirrors.hust.edu.cn/git/lwn.git/atom?h=docs-next-merge</id>
<link rel='self' href='http://mirrors.hust.edu.cn/git/lwn.git/atom?h=docs-next-merge'/>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/'/>
<updated>2016-08-04T12:50:07+00:00</updated>
<entry>
<title>dma-mapping: use unsigned long for dma_attrs</title>
<updated>2016-08-04T12:50:07+00:00</updated>
<author>
<name>Krzysztof Kozlowski</name>
<email>k.kozlowski@samsung.com</email>
</author>
<published>2016-08-03T20:46:00+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=00085f1efa387a8ce100e3734920f7639c80caa3'/>
<id>urn:sha1:00085f1efa387a8ce100e3734920f7639c80caa3</id>
<content type='text'>
The dma-mapping core and the implementations do not change the DMA
attributes passed by pointer.  Thus the pointer can point to const data.
However the attributes do not have to be a bitfield.  Instead unsigned
long will do fine:

1. This is just simpler.  Both in terms of reading the code and setting
   attributes.  Instead of initializing local attributes on the stack
   and passing pointer to it to dma_set_attr(), just set the bits.

2. It brings safeness and checking for const correctness because the
   attributes are passed by value.

Semantic patches for this change (at least most of them):

    virtual patch
    virtual context

    @r@
    identifier f, attrs;

    @@
    f(...,
    - struct dma_attrs *attrs
    + unsigned long attrs
    , ...)
    {
    ...
    }

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

and

    // Options: --all-includes
    virtual patch
    virtual context

    @r@
    identifier f, attrs;
    type t;

    @@
    t f(..., struct dma_attrs *attrs);

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

Link: http://lkml.kernel.org/r/1468399300-5399-2-git-send-email-k.kozlowski@samsung.com
Signed-off-by: Krzysztof Kozlowski &lt;k.kozlowski@samsung.com&gt;
Acked-by: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Acked-by: Robin Murphy &lt;robin.murphy@arm.com&gt;
Acked-by: Hans-Christian Noren Egtvedt &lt;egtvedt@samfundet.no&gt;
Acked-by: Mark Salter &lt;msalter@redhat.com&gt; [c6x]
Acked-by: Jesper Nilsson &lt;jesper.nilsson@axis.com&gt; [cris]
Acked-by: Daniel Vetter &lt;daniel.vetter@ffwll.ch&gt; [drm]
Reviewed-by: Bart Van Assche &lt;bart.vanassche@sandisk.com&gt;
Acked-by: Joerg Roedel &lt;jroedel@suse.de&gt; [iommu]
Acked-by: Fabien Dessenne &lt;fabien.dessenne@st.com&gt; [bdisp]
Reviewed-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt; [vb2-core]
Acked-by: David Vrabel &lt;david.vrabel@citrix.com&gt; [xen]
Acked-by: Konrad Rzeszutek Wilk &lt;konrad.wilk@oracle.com&gt; [xen swiotlb]
Acked-by: Joerg Roedel &lt;jroedel@suse.de&gt; [iommu]
Acked-by: Richard Kuo &lt;rkuo@codeaurora.org&gt; [hexagon]
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt; [m68k]
Acked-by: Gerald Schaefer &lt;gerald.schaefer@de.ibm.com&gt; [s390]
Acked-by: Bjorn Andersson &lt;bjorn.andersson@linaro.org&gt;
Acked-by: Hans-Christian Noren Egtvedt &lt;egtvedt@samfundet.no&gt; [avr32]
Acked-by: Vineet Gupta &lt;vgupta@synopsys.com&gt; [arc]
Acked-by: Robin Murphy &lt;robin.murphy@arm.com&gt; [arm64 and dma-iommu]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>treewide: replace obsolete _refok by __ref</title>
<updated>2016-08-02T21:31:41+00:00</updated>
<author>
<name>Fabian Frederick</name>
<email>fabf@skynet.be</email>
</author>
<published>2016-08-02T21:03:33+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=bd721ea73e1f965569b40620538c942001f76294'/>
<id>urn:sha1:bd721ea73e1f965569b40620538c942001f76294</id>
<content type='text'>
There was only one use of __initdata_refok and __exit_refok

__init_refok was used 46 times against 82 for __ref.

Those definitions are obsolete since commit 312b1485fb50 ("Introduce new
section reference annotations tags: __ref, __refdata, __refconst")

This patch removes the following compatibility definitions and replaces
them treewide.

/* compatibility defines */
#define __init_refok     __ref
#define __initdata_refok __refdata
#define __exit_refok     __ref

I can also provide separate patches if necessary.
(One patch per tree and check in 1 month or 2 to remove old definitions)

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1466796271-3043-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick &lt;fabf@skynet.be&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Sam Ravnborg &lt;sam@ravnborg.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge branch 'akpm' (patches from Andrew)</title>
<updated>2016-07-27T02:55:54+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-07-27T02:55:54+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=0e06f5c0deeef0332a5da2ecb8f1fcf3e024d958'/>
<id>urn:sha1:0e06f5c0deeef0332a5da2ecb8f1fcf3e024d958</id>
<content type='text'>
Merge updates from Andrew Morton:

 - a few misc bits

 - ocfs2

 - most(?) of MM

* emailed patches from Andrew Morton &lt;akpm@linux-foundation.org&gt;: (125 commits)
  thp: fix comments of __pmd_trans_huge_lock()
  cgroup: remove unnecessary 0 check from css_from_id()
  cgroup: fix idr leak for the first cgroup root
  mm: memcontrol: fix documentation for compound parameter
  mm: memcontrol: remove BUG_ON in uncharge_list
  mm: fix build warnings in &lt;linux/compaction.h&gt;
  mm, thp: convert from optimistic swapin collapsing to conservative
  mm, thp: fix comment inconsistency for swapin readahead functions
  thp: update Documentation/{vm/transhuge,filesystems/proc}.txt
  shmem: split huge pages beyond i_size under memory pressure
  thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHE
  khugepaged: add support of collapse for tmpfs/shmem pages
  shmem: make shmem_inode_info::lock irq-safe
  khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page()
  thp: extract khugepaged from mm/huge_memory.c
  shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings
  shmem: add huge pages support
  shmem: get_unmapped_area align huge page
  shmem: prepare huge= mount option and sysfs knob
  mm, rmap: account shmem thp pages
  ...
</content>
</entry>
<entry>
<title>Merge tag 'gpio-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio</title>
<updated>2016-07-27T02:16:01+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-07-27T02:16:01+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=1cd04d293c818687795b83cd8f2626bd4662feeb'/>
<id>urn:sha1:1cd04d293c818687795b83cd8f2626bd4662feeb</id>
<content type='text'>
Pull GPIO updates from Linus Walleij:
 "This is the bulk of GPIO changes for the v4.8 kernel cycle.  The big
  news is the completion of the chardev ABI which I'm very happy about
  and apart from that it's an ordinary, quite busy cycle.  The details
  are below.

  The patches are tested in linux-next for some time, patches to other
  subsystem mostly have ACKs.

  I got overly ambitious with configureing lines as input for IRQ lines
  but it turns out that some controllers have their interrupt-enable and
  input-enabling in orthogonal settings so the assumption that all IRQ
  lines are input lines does not hold.  Oh well, revert and back to the
  drawing board with that.

  Core changes:

   - The big item is of course the completion of the character device
     ABI.  It has now replaced and surpassed the former unmaintainable
     sysfs ABI: we can now hammer (bitbang) individual lines or sets of
     lines and read individual lines or sets of lines from userspace,
     and we can also register to listen to GPIO events from userspace.

     As a tie-in we have two new tools in tools/gpio: gpio-hammer and
     gpio-event-mon that illustrate the proper use of the new ABI.  As
     someone said: the wild west days of GPIO are now over.

   - Continued to remove the pointless ARCH_[WANT_OPTIONAL|REQUIRE]_GPIOLIB
     Kconfig symbols.  I'm patching hexagon, openrisc, powerpc, sh,
     unicore, ia64 and microblaze.  These are either ACKed by their
     maintainers or patched anyways after a grace period and no response
     from maintainers.

     Some archs (ARM) come in from their trees, and others (x86) are
     still not fixed, so I might send a second pull request to root it
     out later in this merge window, or just defer to v4.9.

   - The GPIO tools are moved to the tools build system.

  New drivers:

   - New driver for the MAX77620/MAX20024.

   - New driver for the Intel Merrifield.

   - Enabled PCA953x for the TI PCA9536.

   - Enabled PCA953x for the Intel Edison.

   - Enabled R8A7792 in the RCAR driver.

  Driver improvements:

   - The STMPE and F7188x now supports the .get_direction() callback.

   - The Xilinx driver supports setting multiple lines at once.

   - ACPI support for the Vulcan GPIO controller.

   - The MMIO GPIO driver supports device tree probing.

   - The Acer One 10 is supported through the _DEP ACPI attribute.

  Cleanups:

   - A major cleanup of the OF/DT support code.  It is way easier to
     read and understand now, probably this improves performance too.

   - Drop a few redundant .owner assignments.

   - Remove CLPS711x boardfile support: we are 100% DT"

* tag 'gpio-v4.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (67 commits)
  MAINTAINERS: Add INTEL MERRIFIELD GPIO entry
  gpio: dwapb: add missing fwnode_handle_put() in dwapb_gpio_get_pdata()
  gpio: merrifield: Protect irq_ack() and gpio_set() by lock
  gpio: merrifield: Introduce GPIO driver to support Merrifield
  gpio: intel-mid: Make it depend to X86_INTEL_MID
  gpio: intel-mid: Sort header block alphabetically
  gpio: intel-mid: Remove potentially harmful code
  gpio: rcar: add R8A7792 support
  gpiolib: remove duplicated include from gpiolib.c
  Revert "gpio: convince line to become input in irq helper"
  gpiolib: of_find_gpio(): Don't discard errors
  gpio: of: Allow overriding the device node
  gpio: free handles in fringe cases
  gpio: tps65218: Add platform_device_id table
  gpio: max77620: get gpio value based on direction
  gpio: lynxpoint: avoid potential warning on error path
  tools/gpio: add install section
  tools/gpio: move to tools buildsystem
  gpio: intel-mid: switch to devm_gpiochip_add_data()
  gpio: 74x164: Use spi_write() helper instead of open coding
  ...
</content>
</entry>
<entry>
<title>mm: do not pass mm_struct into handle_mm_fault</title>
<updated>2016-07-26T23:19:19+00:00</updated>
<author>
<name>Kirill A. Shutemov</name>
<email>kirill.shutemov@linux.intel.com</email>
</author>
<published>2016-07-26T22:25:18+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=dcddffd41d3f1d3bdcc1dce3f1cd142779b6d4c1'/>
<id>urn:sha1:dcddffd41d3f1d3bdcc1dce3f1cd142779b6d4c1</id>
<content type='text'>
We always have vma-&gt;vm_mm around.

Link: http://lkml.kernel.org/r/1466021202-61880-8-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>tree wide: get rid of __GFP_REPEAT for order-0 allocations part I</title>
<updated>2016-06-25T00:23:52+00:00</updated>
<author>
<name>Michal Hocko</name>
<email>mhocko@suse.com</email>
</author>
<published>2016-06-24T21:48:47+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=32d6bd9059f265f617f6502c68dfbcae7e515add'/>
<id>urn:sha1:32d6bd9059f265f617f6502c68dfbcae7e515add</id>
<content type='text'>
This is the third version of the patchset previously sent [1].  I have
basically only rebased it on top of 4.7-rc1 tree and dropped "dm: get
rid of superfluous gfp flags" which went through dm tree.  I am sending
it now because it is tree wide and chances for conflicts are reduced
considerably when we want to target rc2.  I plan to send the next step
and rename the flag and move to a better semantic later during this
release cycle so we will have a new semantic ready for 4.8 merge window
hopefully.

Motivation:

While working on something unrelated I've checked the current usage of
__GFP_REPEAT in the tree.  It seems that a majority of the usage is and
always has been bogus because __GFP_REPEAT has always been about costly
high order allocations while we are using it for order-0 or very small
orders very often.  It seems that a big pile of them is just a
copy&amp;paste when a code has been adopted from one arch to another.

I think it makes some sense to get rid of them because they are just
making the semantic more unclear.  Please note that GFP_REPEAT is
documented as

* __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt

* _might_ fail.  This depends upon the particular VM implementation.
  while !costly requests have basically nofail semantic.  So one could
  reasonably expect that order-0 request with __GFP_REPEAT will not loop
  for ever.  This is not implemented right now though.

I would like to move on with __GFP_REPEAT and define a better semantic
for it.

  $ git grep __GFP_REPEAT origin/master | wc -l
  111
  $ git grep __GFP_REPEAT | wc -l
  36

So we are down to the third after this patch series.  The remaining
places really seem to be relying on __GFP_REPEAT due to large allocation
requests.  This still needs some double checking which I will do later
after all the simple ones are sorted out.

I am touching a lot of arch specific code here and I hope I got it right
but as a matter of fact I even didn't compile test for some archs as I
do not have cross compiler for them.  Patches should be quite trivial to
review for stupid compile mistakes though.  The tricky parts are usually
hidden by macro definitions and thats where I would appreciate help from
arch maintainers.

[1] http://lkml.kernel.org/r/1461849846-27209-1-git-send-email-mhocko@kernel.org

This patch (of 19):

__GFP_REPEAT has a rather weak semantic but since it has been introduced
around 2.6.12 it has been ignored for low order allocations.  Yet we
have the full kernel tree with its usage for apparently order-0
allocations.  This is really confusing because __GFP_REPEAT is
explicitly documented to allow allocation failures which is a weaker
semantic than the current order-0 has (basically nofail).

Let's simply drop __GFP_REPEAT from those places.  This would allow to
identify place which really need allocator to retry harder and formulate
a more specific semantic for what the flag is supposed to do actually.

Link: http://lkml.kernel.org/r/1464599699-30131-2-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: "James E.J. Bottomley" &lt;jejb@parisc-linux.org&gt;
Cc: "Theodore Ts'o" &lt;tytso@mit.edu&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Chen Liqin &lt;liqin.linux@gmail.com&gt;
Cc: Chris Metcalf &lt;cmetcalf@mellanox.com&gt; [for tile]
Cc: Guan Xuetao &lt;gxt@mprc.pku.edu.cn&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: John Crispin &lt;blogic@openwrt.org&gt;
Cc: Lennox Wu &lt;lennox.wu@gmail.com&gt;
Cc: Ley Foon Tan &lt;lftan@altera.com&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Matt Fleming &lt;matt@codeblueprint.co.uk&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>openrisc: do away with ARCH_REQUIRE_GPIOLIB</title>
<updated>2016-06-08T07:54:19+00:00</updated>
<author>
<name>Linus Walleij</name>
<email>linus.walleij@linaro.org</email>
</author>
<published>2016-04-19T11:15:43+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=8636f344cf14e0b06a3f9aeaca5ac5c3f7d0d055'/>
<id>urn:sha1:8636f344cf14e0b06a3f9aeaca5ac5c3f7d0d055</id>
<content type='text'>
Replace "select ARCH_REQUIRE_GPIOLIB" with "select GPIOLIB"
as this can now be selected directly.

Cc: Michael Büsch &lt;m@bues.ch&gt;
Cc: Jonas Bonn &lt;jonas@southpole.se&gt;
Cc: linux@lists.openrisc.net
Signed-off-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'asm-generic-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic</title>
<updated>2016-05-24T22:24:37+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2016-05-24T22:24:37+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=d04f90ffecb7f6d7358197d7544f5536b6d4d8cc'/>
<id>urn:sha1:d04f90ffecb7f6d7358197d7544f5536b6d4d8cc</id>
<content type='text'>
Pull asm-generic cleanup from Arnd Bergmann:
 "I have only one patch for asm-generic in this release, this one is
  from James Hogan and updates the generic system call table for
  renameat2 so we don't need to provide both renameat and renameat2 in
  newly added architectures"

* tag 'asm-generic-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  asm-generic: Drop renameat syscall from default list
</content>
</entry>
<entry>
<title>lib/GCD.c: use binary GCD algorithm instead of Euclidean</title>
<updated>2016-05-21T00:58:30+00:00</updated>
<author>
<name>Zhaoxiu Zeng</name>
<email>zhaoxiu.zeng@gmail.com</email>
</author>
<published>2016-05-21T00:03:57+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=fff7fb0b2d908dec779783d8eaf3d7725230f75e'/>
<id>urn:sha1:fff7fb0b2d908dec779783d8eaf3d7725230f75e</id>
<content type='text'>
The binary GCD algorithm is based on the following facts:
	1. If a and b are all evens, then gcd(a,b) = 2 * gcd(a/2, b/2)
	2. If a is even and b is odd, then gcd(a,b) = gcd(a/2, b)
	3. If a and b are all odds, then gcd(a,b) = gcd((a-b)/2, b) = gcd((a+b)/2, b)

Even on x86 machines with reasonable division hardware, the binary
algorithm runs about 25% faster (80% the execution time) than the
division-based Euclidian algorithm.

On platforms like Alpha and ARMv6 where division is a function call to
emulation code, it's even more significant.

There are two variants of the code here, depending on whether a fast
__ffs (find least significant set bit) instruction is available.  This
allows the unpredictable branches in the bit-at-a-time shifting loop to
be eliminated.

If fast __ffs is not available, the "even/odd" GCD variant is used.

I use the following code to benchmark:

	#include &lt;stdio.h&gt;
	#include &lt;stdlib.h&gt;
	#include &lt;stdint.h&gt;
	#include &lt;string.h&gt;
	#include &lt;time.h&gt;
	#include &lt;unistd.h&gt;

	#define swap(a, b) \
		do { \
			a ^= b; \
			b ^= a; \
			a ^= b; \
		} while (0)

	unsigned long gcd0(unsigned long a, unsigned long b)
	{
		unsigned long r;

		if (a &lt; b) {
			swap(a, b);
		}

		if (b == 0)
			return a;

		while ((r = a % b) != 0) {
			a = b;
			b = r;
		}

		return b;
	}

	unsigned long gcd1(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		b &gt;&gt;= __builtin_ctzl(b);

		for (;;) {
			a &gt;&gt;= __builtin_ctzl(a);
			if (a == b)
				return a &lt;&lt; __builtin_ctzl(r);

			if (a &lt; b)
				swap(a, b);
			a -= b;
		}
	}

	unsigned long gcd2(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		r &amp;= -r;

		while (!(b &amp; r))
			b &gt;&gt;= 1;

		for (;;) {
			while (!(a &amp; r))
				a &gt;&gt;= 1;
			if (a == b)
				return a;

			if (a &lt; b)
				swap(a, b);
			a -= b;
			a &gt;&gt;= 1;
			if (a &amp; r)
				a += b;
			a &gt;&gt;= 1;
		}
	}

	unsigned long gcd3(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		b &gt;&gt;= __builtin_ctzl(b);
		if (b == 1)
			return r &amp; -r;

		for (;;) {
			a &gt;&gt;= __builtin_ctzl(a);
			if (a == 1)
				return r &amp; -r;
			if (a == b)
				return a &lt;&lt; __builtin_ctzl(r);

			if (a &lt; b)
				swap(a, b);
			a -= b;
		}
	}

	unsigned long gcd4(unsigned long a, unsigned long b)
	{
		unsigned long r = a | b;

		if (!a || !b)
			return r;

		r &amp;= -r;

		while (!(b &amp; r))
			b &gt;&gt;= 1;
		if (b == r)
			return r;

		for (;;) {
			while (!(a &amp; r))
				a &gt;&gt;= 1;
			if (a == r)
				return r;
			if (a == b)
				return a;

			if (a &lt; b)
				swap(a, b);
			a -= b;
			a &gt;&gt;= 1;
			if (a &amp; r)
				a += b;
			a &gt;&gt;= 1;
		}
	}

	static unsigned long (*gcd_func[])(unsigned long a, unsigned long b) = {
		gcd0, gcd1, gcd2, gcd3, gcd4,
	};

	#define TEST_ENTRIES (sizeof(gcd_func) / sizeof(gcd_func[0]))

	#if defined(__x86_64__)

	#define rdtscll(val) do { \
		unsigned long __a,__d; \
		__asm__ __volatile__("rdtsc" : "=a" (__a), "=d" (__d)); \
		(val) = ((unsigned long long)__a) | (((unsigned long long)__d)&lt;&lt;32); \
	} while(0)

	static unsigned long long benchmark_gcd_func(unsigned long (*gcd)(unsigned long, unsigned long),
								unsigned long a, unsigned long b, unsigned long *res)
	{
		unsigned long long start, end;
		unsigned long long ret;
		unsigned long gcd_res;

		rdtscll(start);
		gcd_res = gcd(a, b);
		rdtscll(end);

		if (end &gt;= start)
			ret = end - start;
		else
			ret = ~0ULL - start + 1 + end;

		*res = gcd_res;
		return ret;
	}

	#else

	static inline struct timespec read_time(void)
	{
		struct timespec time;
		clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &amp;time);
		return time;
	}

	static inline unsigned long long diff_time(struct timespec start, struct timespec end)
	{
		struct timespec temp;

		if ((end.tv_nsec - start.tv_nsec) &lt; 0) {
			temp.tv_sec = end.tv_sec - start.tv_sec - 1;
			temp.tv_nsec = 1000000000ULL + end.tv_nsec - start.tv_nsec;
		} else {
			temp.tv_sec = end.tv_sec - start.tv_sec;
			temp.tv_nsec = end.tv_nsec - start.tv_nsec;
		}

		return temp.tv_sec * 1000000000ULL + temp.tv_nsec;
	}

	static unsigned long long benchmark_gcd_func(unsigned long (*gcd)(unsigned long, unsigned long),
								unsigned long a, unsigned long b, unsigned long *res)
	{
		struct timespec start, end;
		unsigned long gcd_res;

		start = read_time();
		gcd_res = gcd(a, b);
		end = read_time();

		*res = gcd_res;
		return diff_time(start, end);
	}

	#endif

	static inline unsigned long get_rand()
	{
		if (sizeof(long) == 8)
			return (unsigned long)rand() &lt;&lt; 32 | rand();
		else
			return rand();
	}

	int main(int argc, char **argv)
	{
		unsigned int seed = time(0);
		int loops = 100;
		int repeats = 1000;
		unsigned long (*res)[TEST_ENTRIES];
		unsigned long long elapsed[TEST_ENTRIES];
		int i, j, k;

		for (;;) {
			int opt = getopt(argc, argv, "n:r:s:");
			/* End condition always first */
			if (opt == -1)
				break;

			switch (opt) {
			case 'n':
				loops = atoi(optarg);
				break;
			case 'r':
				repeats = atoi(optarg);
				break;
			case 's':
				seed = strtoul(optarg, NULL, 10);
				break;
			default:
				/* You won't actually get here. */
				break;
			}
		}

		res = malloc(sizeof(unsigned long) * TEST_ENTRIES * loops);
		memset(elapsed, 0, sizeof(elapsed));

		srand(seed);
		for (j = 0; j &lt; loops; j++) {
			unsigned long a = get_rand();
			/* Do we have args? */
			unsigned long b = argc &gt; optind ? strtoul(argv[optind], NULL, 10) : get_rand();
			unsigned long long min_elapsed[TEST_ENTRIES];
			for (k = 0; k &lt; repeats; k++) {
				for (i = 0; i &lt; TEST_ENTRIES; i++) {
					unsigned long long tmp = benchmark_gcd_func(gcd_func[i], a, b, &amp;res[j][i]);
					if (k == 0 || min_elapsed[i] &gt; tmp)
						min_elapsed[i] = tmp;
				}
			}
			for (i = 0; i &lt; TEST_ENTRIES; i++)
				elapsed[i] += min_elapsed[i];
		}

		for (i = 0; i &lt; TEST_ENTRIES; i++)
			printf("gcd%d: elapsed %llu\n", i, elapsed[i]);

		k = 0;
		srand(seed);
		for (j = 0; j &lt; loops; j++) {
			unsigned long a = get_rand();
			unsigned long b = argc &gt; optind ? strtoul(argv[optind], NULL, 10) : get_rand();
			for (i = 1; i &lt; TEST_ENTRIES; i++) {
				if (res[j][i] != res[j][0])
					break;
			}
			if (i &lt; TEST_ENTRIES) {
				if (k == 0) {
					k = 1;
					fprintf(stderr, "Error:\n");
				}
				fprintf(stderr, "gcd(%lu, %lu): ", a, b);
				for (i = 0; i &lt; TEST_ENTRIES; i++)
					fprintf(stderr, "%ld%s", res[j][i], i &lt; TEST_ENTRIES - 1 ? ", " : "\n");
			}
		}

		if (k == 0)
			fprintf(stderr, "PASS\n");

		free(res);

		return 0;
	}

Compiled with "-O2", on "VirtualBox 4.4.0-22-generic #38-Ubuntu x86_64" got:

  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 10174
  gcd1: elapsed 2120
  gcd2: elapsed 2902
  gcd3: elapsed 2039
  gcd4: elapsed 2812
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9309
  gcd1: elapsed 2280
  gcd2: elapsed 2822
  gcd3: elapsed 2217
  gcd4: elapsed 2710
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9589
  gcd1: elapsed 2098
  gcd2: elapsed 2815
  gcd3: elapsed 2030
  gcd4: elapsed 2718
  PASS
  zhaoxiuzeng@zhaoxiuzeng-VirtualBox:~/develop$ ./gcd -r 500000 -n 10
  gcd0: elapsed 9914
  gcd1: elapsed 2309
  gcd2: elapsed 2779
  gcd3: elapsed 2228
  gcd4: elapsed 2709
  PASS

[akpm@linux-foundation.org: avoid #defining a CONFIG_ variable]
Signed-off-by: Zhaoxiu Zeng &lt;zhaoxiu.zeng@gmail.com&gt;
Signed-off-by: George Spelvin &lt;linux@horizon.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>exit_thread: remove empty bodies</title>
<updated>2016-05-21T00:58:30+00:00</updated>
<author>
<name>Jiri Slaby</name>
<email>jslaby@suse.cz</email>
</author>
<published>2016-05-21T00:00:16+00:00</published>
<link rel='alternate' type='text/html' href='http://mirrors.hust.edu.cn/git/lwn.git/commit/?id=5f56a5dfdb9bcb3bca03df59980d4d2f012cbb53'/>
<id>urn:sha1:5f56a5dfdb9bcb3bca03df59980d4d2f012cbb53</id>
<content type='text'>
Define HAVE_EXIT_THREAD for archs which want to do something in
exit_thread. For others, let's define exit_thread as an empty inline.

This is a cleanup before we change the prototype of exit_thread to
accept a task parameter.

[akpm@linux-foundation.org: fix mips]
Signed-off-by: Jiri Slaby &lt;jslaby@suse.cz&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: "James E.J. Bottomley" &lt;jejb@parisc-linux.org&gt;
Cc: Aurelien Jacquiot &lt;a-jacquiot@ti.com&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Chen Liqin &lt;liqin.linux@gmail.com&gt;
Cc: Chris Metcalf &lt;cmetcalf@mellanox.com&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Guan Xuetao &lt;gxt@mprc.pku.edu.cn&gt;
Cc: Haavard Skinnemoen &lt;hskinnemoen@gmail.com&gt;
Cc: Hans-Christian Egtvedt &lt;egtvedt@samfundet.no&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: James Hogan &lt;james.hogan@imgtec.com&gt;
Cc: Jeff Dike &lt;jdike@addtoit.com&gt;
Cc: Jesper Nilsson &lt;jesper.nilsson@axis.com&gt;
Cc: Jiri Slaby &lt;jslaby@suse.cz&gt;
Cc: Jonas Bonn &lt;jonas@southpole.se&gt;
Cc: Koichi Yasutake &lt;yasutake.koichi@jp.panasonic.com&gt;
Cc: Lennox Wu &lt;lennox.wu@gmail.com&gt;
Cc: Ley Foon Tan &lt;lftan@altera.com&gt;
Cc: Mark Salter &lt;msalter@redhat.com&gt;
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Mikael Starvik &lt;starvik@axis.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Richard Kuo &lt;rkuo@codeaurora.org&gt;
Cc: Richard Weinberger &lt;richard@nod.at&gt;
Cc: Russell King &lt;linux@arm.linux.org.uk&gt;
Cc: Steven Miao &lt;realmz6@gmail.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
</feed>
