There is no need to schedule a bottomhalf for either of them. One is fast
and the another schedules a bottomhalf itself.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Acked-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the architecture specific __cmpxchg_u32 for 32 bits cmpxchg)_local. Else,
use the new generic cmpxchg_local (disables interrupt).
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Miles Bader <miles.bader@necel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use cmpxchg_u32 and cmpxchg_u64 for cmpxchg_local and cmpxchg64_local. For other
type sizes, use the new generic cmpxchg_local (disables interrupt).

Change:
Since the header depends on local_irqsave/local_irqrestore, it must be
included after their declaration.

Actually, being below the
#include <linux/irqflags.h> should be enough, and on sparc64 it is
included at the beginning of system.h.

So it makes sense to move it up for sparc64.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move cmpxchg and add cmpxchg_local to system.h.
Use the new generic cmpxchg_local (disables interrupt).
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the standard __cmpxchg for every type that can be updated atomically.
Use the new generic cmpxchg_local (disables interrupt) for other types.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a local processor version of cmpxchg for ppc.

Implements __cmpxchg_u32_local and uses it for 32 bits cmpxchg_local.
It uses the non NMI safe cmpxchg_local_generic for 1, 2 and 8 bytes
cmpxchg_local.
Signed-off-by: NGunnar Larisch <gl@denx.de>
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Kumar Gala <galak@gate.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On m32r, use the new cmpxchg_local as primitive for the local_cmpxchg
operation.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NHirokazu Takata <takata@linux-m32r.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

the #endif  /* CONFIG_SMP */ should cover the default condition, or it may cause
bad parameter to be silently missed.

To make it work correctly, we have to remove the ifdef CONFIG SMP surrounding
__xchg_called_with_bad_pointer declaration. Thanks to Adrian Bunk for detecting
this.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NHirokazu Takata <takata@linux-m32r.org>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add __xchg_local, xchg_local (define), __cmpxchg_local_u32, __cmpxchg_local,
cmpxchg_local(macro).

cmpxchg_local and cmpxchg64_local will use the architecture specific
__cmpxchg_local_u32 for 32 bits arguments, and use the generic
__cmpxchg_local_generic for 8, 16 and 64 bits arguments.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NHirokazu Takata <takata@linux-m32r.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add the primitives cmpxchg_local, cmpxchg64 and cmpxchg64_local to ia64. They
use cmpxchg_acq as underlying macro, just like the already existing ia64
cmpxchg().

Changelog:

ia64 cmpxchg_local coding style fix
Quoting Keith Owens:

As a matter of coding style, I prefer

#define cmpxchg_local   cmpxchg
#define cmpxchg64_local cmpxchg64

Which makes it absolutely clear that they are the same code.  With your
patch, humans have to do a string compare of two defines to see if they
are the same.

Note cmpxchg is *not* a performance win vs interrupt disable / enable on IA64.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Keith Owens <kaos@ocs.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt) for 8, 16 and 64 bits
arguments. Use the 32 bits cmpxchg available on the architecture for 32 bits
arguments.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Mikael Starvik <starvik@axis.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set since nobody seems to know why __cmpxchg
has been implemented in assembly in the first place thather than in plain C.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Michael Frysinger <michael.frysinger@analog.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt) for 8, 16 and 64 bits
cmpxchg_local. Use the __cmpxchg_u32 primitive for 32 bits cmpxchg_local.

Note that cmpxchg only uses the __cmpxchg_u32 or __cmpxchg_u64 and will cause
a linker error if called with 8 or 16 bits argument.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NHaavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic cmpxchg_local (disables interrupt). Also use the generic
cmpxchg as fallback if SMP is not set.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure that at least cmpxchg64_local is available on all architectures to use
for unsigned long long values.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Andi Kleen <ak@muc.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure that at least cmpxchg64_local is available on all architectures to use
for unsigned long long values.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: NPaul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure that at least cmpxchg64_local is available on all architectures to use
for unsigned long long values.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure that at least cmpxchg64_local is available on all architectures to use
for unsigned long long values.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Emulates the cmpxchg_local by disabling interrupts around variable modification.
This is not reentrant wrt NMIs and MCEs. It is only protected against normal
interrupts, but this is enough for architectures without such interrupt sources
or if used in a context where the data is not shared with such handlers.

It can be used as a fallback for architectures lacking a real cmpxchg
instruction.

For architectures that have a real cmpxchg but does not have NMIs or MCE,
testing which of the generic vs architecture specific cmpxchg is the fastest
should be done.

asm-generic/cmpxchg.h defines a cmpxchg that uses cmpxchg_local. It is meant to
be used as a cmpxchg fallback for architectures that do not support SMP.

* Patch series comments

Using cmpxchg_local shows a performance improvements of the fast path goes from
a 66% speedup on a Pentium 4 to a 14% speedup on AMD64.

In detail:
Tested-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Measurements on a Pentium4, 3GHz, Hyperthread.
SLUB Performance testing
========================
1. Kmalloc: Repeatedly allocate then free test

* slub HEAD, test 1
kmalloc(8) = 201 cycles         kfree = 351 cycles
kmalloc(16) = 198 cycles        kfree = 359 cycles
kmalloc(32) = 200 cycles        kfree = 381 cycles
kmalloc(64) = 224 cycles        kfree = 394 cycles
kmalloc(128) = 285 cycles       kfree = 424 cycles
kmalloc(256) = 411 cycles       kfree = 546 cycles
kmalloc(512) = 480 cycles       kfree = 619 cycles
kmalloc(1024) = 623 cycles      kfree = 750 cycles
kmalloc(2048) = 686 cycles      kfree = 811 cycles
kmalloc(4096) = 482 cycles      kfree = 538 cycles
kmalloc(8192) = 680 cycles      kfree = 734 cycles
kmalloc(16384) = 713 cycles     kfree = 843 cycles

* Slub HEAD, test 2
kmalloc(8) = 190 cycles         kfree = 351 cycles
kmalloc(16) = 195 cycles        kfree = 360 cycles
kmalloc(32) = 201 cycles        kfree = 370 cycles
kmalloc(64) = 245 cycles        kfree = 389 cycles
kmalloc(128) = 283 cycles       kfree = 413 cycles
kmalloc(256) = 409 cycles       kfree = 547 cycles
kmalloc(512) = 476 cycles       kfree = 616 cycles
kmalloc(1024) = 628 cycles      kfree = 753 cycles
kmalloc(2048) = 684 cycles      kfree = 811 cycles
kmalloc(4096) = 480 cycles      kfree = 539 cycles
kmalloc(8192) = 661 cycles      kfree = 746 cycles
kmalloc(16384) = 741 cycles     kfree = 856 cycles

* cmpxchg_local Slub test
kmalloc(8) = 83 cycles          kfree = 363 cycles
kmalloc(16) = 85 cycles         kfree = 372 cycles
kmalloc(32) = 92 cycles         kfree = 377 cycles
kmalloc(64) = 115 cycles        kfree = 397 cycles
kmalloc(128) = 179 cycles       kfree = 438 cycles
kmalloc(256) = 314 cycles       kfree = 564 cycles
kmalloc(512) = 398 cycles       kfree = 615 cycles
kmalloc(1024) = 573 cycles      kfree = 745 cycles
kmalloc(2048) = 629 cycles      kfree = 816 cycles
kmalloc(4096) = 473 cycles      kfree = 548 cycles
kmalloc(8192) = 659 cycles      kfree = 745 cycles
kmalloc(16384) = 724 cycles     kfree = 843 cycles

2. Kmalloc: alloc/free test

* slub HEAD, test 1
kmalloc(8)/kfree = 322 cycles
kmalloc(16)/kfree = 318 cycles
kmalloc(32)/kfree = 318 cycles
kmalloc(64)/kfree = 325 cycles
kmalloc(128)/kfree = 318 cycles
kmalloc(256)/kfree = 328 cycles
kmalloc(512)/kfree = 328 cycles
kmalloc(1024)/kfree = 328 cycles
kmalloc(2048)/kfree = 328 cycles
kmalloc(4096)/kfree = 678 cycles
kmalloc(8192)/kfree = 1013 cycles
kmalloc(16384)/kfree = 1157 cycles

* Slub HEAD, test 2
kmalloc(8)/kfree = 323 cycles
kmalloc(16)/kfree = 318 cycles
kmalloc(32)/kfree = 318 cycles
kmalloc(64)/kfree = 318 cycles
kmalloc(128)/kfree = 318 cycles
kmalloc(256)/kfree = 328 cycles
kmalloc(512)/kfree = 328 cycles
kmalloc(1024)/kfree = 328 cycles
kmalloc(2048)/kfree = 328 cycles
kmalloc(4096)/kfree = 648 cycles
kmalloc(8192)/kfree = 1009 cycles
kmalloc(16384)/kfree = 1105 cycles

* cmpxchg_local Slub test
kmalloc(8)/kfree = 112 cycles
kmalloc(16)/kfree = 103 cycles
kmalloc(32)/kfree = 103 cycles
kmalloc(64)/kfree = 103 cycles
kmalloc(128)/kfree = 112 cycles
kmalloc(256)/kfree = 111 cycles
kmalloc(512)/kfree = 111 cycles
kmalloc(1024)/kfree = 111 cycles
kmalloc(2048)/kfree = 121 cycles
kmalloc(4096)/kfree = 650 cycles
kmalloc(8192)/kfree = 1042 cycles
kmalloc(16384)/kfree = 1149 cycles
Tested-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Measurements on a AMD64 2.0 GHz dual-core

In this test, we seem to remove 10 cycles from the kmalloc fast path.
On small allocations, it gives a 14% performance increase. kfree fast
path also seems to have a 10 cycles improvement.

1. Kmalloc: Repeatedly allocate then free test

* cmpxchg_local slub
kmalloc(8) = 63 cycles      kfree = 126 cycles
kmalloc(16) = 66 cycles     kfree = 129 cycles
kmalloc(32) = 76 cycles     kfree = 138 cycles
kmalloc(64) = 100 cycles    kfree = 288 cycles
kmalloc(128) = 128 cycles   kfree = 309 cycles
kmalloc(256) = 170 cycles   kfree = 315 cycles
kmalloc(512) = 221 cycles   kfree = 357 cycles
kmalloc(1024) = 324 cycles  kfree = 393 cycles
kmalloc(2048) = 354 cycles  kfree = 440 cycles
kmalloc(4096) = 394 cycles  kfree = 330 cycles
kmalloc(8192) = 523 cycles  kfree = 481 cycles
kmalloc(16384) = 643 cycles kfree = 649 cycles

* Base
kmalloc(8) = 74 cycles      kfree = 113 cycles
kmalloc(16) = 76 cycles     kfree = 116 cycles
kmalloc(32) = 85 cycles     kfree = 133 cycles
kmalloc(64) = 111 cycles    kfree = 279 cycles
kmalloc(128) = 138 cycles   kfree = 294 cycles
kmalloc(256) = 181 cycles   kfree = 304 cycles
kmalloc(512) = 237 cycles   kfree = 327 cycles
kmalloc(1024) = 340 cycles  kfree = 379 cycles
kmalloc(2048) = 378 cycles  kfree = 433 cycles
kmalloc(4096) = 399 cycles  kfree = 329 cycles
kmalloc(8192) = 528 cycles  kfree = 624 cycles
kmalloc(16384) = 651 cycles kfree = 737 cycles

2. Kmalloc: alloc/free test

* cmpxchg_local slub
kmalloc(8)/kfree = 96 cycles
kmalloc(16)/kfree = 97 cycles
kmalloc(32)/kfree = 97 cycles
kmalloc(64)/kfree = 97 cycles
kmalloc(128)/kfree = 97 cycles
kmalloc(256)/kfree = 105 cycles
kmalloc(512)/kfree = 108 cycles
kmalloc(1024)/kfree = 105 cycles
kmalloc(2048)/kfree = 107 cycles
kmalloc(4096)/kfree = 390 cycles
kmalloc(8192)/kfree = 626 cycles
kmalloc(16384)/kfree = 662 cycles

* Base
kmalloc(8)/kfree = 116 cycles
kmalloc(16)/kfree = 116 cycles
kmalloc(32)/kfree = 116 cycles
kmalloc(64)/kfree = 116 cycles
kmalloc(128)/kfree = 116 cycles
kmalloc(256)/kfree = 126 cycles
kmalloc(512)/kfree = 126 cycles
kmalloc(1024)/kfree = 126 cycles
kmalloc(2048)/kfree = 126 cycles
kmalloc(4096)/kfree = 384 cycles
kmalloc(8192)/kfree = 749 cycles
kmalloc(16384)/kfree = 786 cycles
Tested-by: NChristoph Lameter <clameter@sgi.com>
I can confirm Mathieus' measurement now:

Athlon64:

regular NUMA/discontig

1. Kmalloc: Repeatedly allocate then free test
10000 times kmalloc(8) -> 79 cycles kfree -> 92 cycles
10000 times kmalloc(16) -> 79 cycles kfree -> 93 cycles
10000 times kmalloc(32) -> 88 cycles kfree -> 95 cycles
10000 times kmalloc(64) -> 124 cycles kfree -> 132 cycles
10000 times kmalloc(128) -> 157 cycles kfree -> 247 cycles
10000 times kmalloc(256) -> 200 cycles kfree -> 257 cycles
10000 times kmalloc(512) -> 250 cycles kfree -> 277 cycles
10000 times kmalloc(1024) -> 337 cycles kfree -> 314 cycles
10000 times kmalloc(2048) -> 365 cycles kfree -> 330 cycles
10000 times kmalloc(4096) -> 352 cycles kfree -> 240 cycles
10000 times kmalloc(8192) -> 456 cycles kfree -> 340 cycles
10000 times kmalloc(16384) -> 646 cycles kfree -> 471 cycles
2. Kmalloc: alloc/free test
10000 times kmalloc(8)/kfree -> 124 cycles
10000 times kmalloc(16)/kfree -> 124 cycles
10000 times kmalloc(32)/kfree -> 124 cycles
10000 times kmalloc(64)/kfree -> 124 cycles
10000 times kmalloc(128)/kfree -> 124 cycles
10000 times kmalloc(256)/kfree -> 132 cycles
10000 times kmalloc(512)/kfree -> 132 cycles
10000 times kmalloc(1024)/kfree -> 132 cycles
10000 times kmalloc(2048)/kfree -> 132 cycles
10000 times kmalloc(4096)/kfree -> 319 cycles
10000 times kmalloc(8192)/kfree -> 486 cycles
10000 times kmalloc(16384)/kfree -> 539 cycles

cmpxchg_local NUMA/discontig

1. Kmalloc: Repeatedly allocate then free test
10000 times kmalloc(8) -> 55 cycles kfree -> 90 cycles
10000 times kmalloc(16) -> 55 cycles kfree -> 92 cycles
10000 times kmalloc(32) -> 70 cycles kfree -> 91 cycles
10000 times kmalloc(64) -> 100 cycles kfree -> 141 cycles
10000 times kmalloc(128) -> 128 cycles kfree -> 233 cycles
10000 times kmalloc(256) -> 172 cycles kfree -> 251 cycles
10000 times kmalloc(512) -> 225 cycles kfree -> 275 cycles
10000 times kmalloc(1024) -> 325 cycles kfree -> 311 cycles
10000 times kmalloc(2048) -> 346 cycles kfree -> 330 cycles
10000 times kmalloc(4096) -> 351 cycles kfree -> 238 cycles
10000 times kmalloc(8192) -> 450 cycles kfree -> 342 cycles
10000 times kmalloc(16384) -> 630 cycles kfree -> 546 cycles
2. Kmalloc: alloc/free test
10000 times kmalloc(8)/kfree -> 81 cycles
10000 times kmalloc(16)/kfree -> 81 cycles
10000 times kmalloc(32)/kfree -> 81 cycles
10000 times kmalloc(64)/kfree -> 81 cycles
10000 times kmalloc(128)/kfree -> 81 cycles
10000 times kmalloc(256)/kfree -> 91 cycles
10000 times kmalloc(512)/kfree -> 90 cycles
10000 times kmalloc(1024)/kfree -> 91 cycles
10000 times kmalloc(2048)/kfree -> 90 cycles
10000 times kmalloc(4096)/kfree -> 318 cycles
10000 times kmalloc(8192)/kfree -> 483 cycles
10000 times kmalloc(16384)/kfree -> 536 cycles

Changelog:
- Ran though checkpatch.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct user.u_ar0 is defined to contain a pointer offset on all
architectures in which it is defined (all architectures which define an
a.out format except SPARC.) However, it has a pointer type in the headers,
which is pointless -- <asm/user.h> is not exported to userspace, and it
just makes the code messy.

Redefine the field as "unsigned long" (which is the same size as a pointer
on all Linux architectures) and change the setting code to user offsetof()
instead of hand-coded arithmetic.

Cc: Linux Arch Mailing List <linux-arch@vger.kernel.org>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Cc: Håvard Skinnemoen <hskinnemoen@atmel.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ralf Baechle <ralf@linux-mips.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>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Do not export asm/page.h during make headers_install.  This removes PAGE_SIZE
from userspace headers.
Signed-off-by: NKirill A. Shutemov <k.shutemov@gmail.com>
Reviewed-by: NDavid Woodhouse <dwmw2@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Do not export asm/elf.h during make headers_install.
Signed-off-by: NKirill A. Shutemov <k.shutemov@gmail.com>
Reviewed-by: NDavid Woodhouse <dwmw2@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

asm/elf.h, asm/page.h and asm/user.h don't export to userspace now, so we can
drop #ifdef __KERNEL__ for them.

[k.shutemov@gmail.com: remove #ifdef __KERNEL_]
Signed-off-by: NKirill A. Shutemov <k.shutemov@gmail.com>
Reviewed-by: NDavid Woodhouse <dwmw2@infradead.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NKirill A. Shutemov <k.shutemov@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Do not export asm/user.h and linux/user.h during make headers_install.
Signed-off-by: NKirill A. Shutemov <k.shutemov@gmail.com>
Reviewed-by: NDavid Woodhouse <dwmw2@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the old iget() call and the read_inode() superblock operation it uses
as these are really obsolete, and the use of read_inode() does not produce
proper error handling (no distinction between ENOMEM and EIO when marking an
inode bad).

Furthermore, this removes the temptation to use iget() to find an inode by
number in a filesystem from code outside that filesystem.

iget_locked() should be used instead.  A new function is added in an earlier
patch (iget_failed) that is to be called to mark an inode as bad, unlock it
and release it should the get routine fail.  Mark iget() and read_inode() as
being obsolete and remove references to them from the documentation.

Typically a filesystem will be modified such that the read_inode function
becomes an internal iget function, for example the following:

	void thingyfs_read_inode(struct inode *inode)
	{
		...
	}

would be changed into something like:

	struct inode *thingyfs_iget(struct super_block *sp, unsigned long ino)
	{
		struct inode *inode;
		int ret;

		inode = iget_locked(sb, ino);
		if (!inode)
			return ERR_PTR(-ENOMEM);
		if (!(inode->i_state & I_NEW))
			return inode;

		...
		unlock_new_inode(inode);
		return inode;
	error:
		iget_failed(inode);
		return ERR_PTR(ret);
	}

and then thingyfs_iget() would be called rather than iget(), for example:

	ret = -EINVAL;
	inode = iget(sb, ino);
	if (!inode || is_bad_inode(inode))
		goto error;

becomes:

	inode = thingyfs_iget(sb, ino);
	if (IS_ERR(inode)) {
		ret = PTR_ERR(inode);
		goto error;
	}

Note that is_bad_inode() does not need to be called.  The error returned by
thingyfs_iget() should render it unnecessary.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stop the QNX4 filesystem from using iget() and read_inode().  Replace
qnx4_read_inode() with qnx4_iget(), and call that instead of iget().
qnx4_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

qnx4_fill_super() returns any error incurred when getting the root inode
instead of EINVAL.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Cc: Anders Larsen <al@alarsen.net>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stop the EXT4 filesystem from using iget() and read_inode().  Replace
ext4_read_inode() with ext4_iget(), and call that instead of iget().
ext4_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

ext4_fill_super() returns any error incurred when getting the root inode
instead of EINVAL.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stop the EXT3 filesystem from using iget() and read_inode().  Replace
ext3_read_inode() with ext3_iget(), and call that instead of iget().
ext3_iget() then uses iget_locked() directly and returns a proper error code
instead of an inode in the event of an error.

ext3_fill_super() returns any error incurred when getting the root inode
instead of EINVAL.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: N"Theodore Ts'o" <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stop the EFS filesystem from using iget() and read_inode().  Replace
efs_read_inode() with efs_iget(), and call that instead of iget().  efs_iget()
then uses iget_locked() directly and returns a proper error code instead of an
inode in the event of an error.

efs_fill_super() returns any error incurred when getting the root inode
instead of EACCES.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce a function to register failure in an inode construction path.  This
includes marking the inode under construction as bad, unlocking it and
releasing it.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add an ERR_CAST() function to complement ERR_PTR and co.  for the purposes
of casting an error entyped as one pointer type to an error of another
pointer type whilst making it explicit as to what is going on.

This provides a replacement for the ERR_PTR(PTR_ERR(p)) construct.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For readability, all the calls to vmcoreinfo_append_str() are changed to macros
having a prefix "VMCOREINFO_".

This discussion is the following:
http://www.ussg.iu.edu/hypermail/linux/kernel/0709.3/0584.htmlSigned-off-by: NKen'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: NSimon Horman <horms@verge.net.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It is better that the existing offsetof() is used for VMCOREINFO_OFFSET().

This discussion is the following:
http://www.ussg.iu.edu/hypermail/linux/kernel/0709.3/0584.htmlSigned-off-by: NKen'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: NSimon Horman <horms@verge.net.au>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>