Skip to content

L
linux
An error occurred fetching the project authors.
Switch branch/tag
  1. 02 Sep, 2013 1 commit
    • Linus Torvalds's avatar
      lockref: implement lockless reference count updates using cmpxchg() · bc08b449
      Linus Torvalds authored 
      Instead of taking the spinlock, the lockless versions atomically check
that the lock is not taken, and do the reference count update using a
cmpxchg() loop.  This is semantically identical to doing the reference
count update protected by the lock, but avoids the "wait for lock"
contention that you get when accesses to the reference count are
contended.

Note that a "lockref" is absolutely _not_ equivalent to an atomic_t.
Even when the lockref reference counts are updated atomically with
cmpxchg, the fact that they also verify the state of the spinlock means
that the lockless updates can never happen while somebody else holds the
spinlock.

So while "lockref_put_or_lock()" looks a lot like just another name for
"atomic_dec_and_lock()", and both optimize to lockless updates, they are
fundamentally different: the decrement done by atomic_dec_and_lock() is
truly independent of any lock (as long as it doesn't decrement to zero),
so a locked region can still see the count change.

The lockref structure, in contrast, really is a *locked* reference
count.  If you hold the spinlock, the reference count will be stable and
you can modify the reference count without using atomics, because even
the lockless updates will see and respect the state of the lock.

In order to enable the cmpxchg lockless code, the architecture needs to
do three things:

 (1) Make sure that the "arch_spinlock_t" and an "unsigned int" can fit
     in an aligned u64, and have a "cmpxchg()" implementation that works
     on such a u64 data type.

 (2) define a helper function to test for a spinlock being unlocked
     ("arch_spin_value_unlocked()")

 (3) select the "ARCH_USE_CMPXCHG_LOCKREF" config variable in its
     Kconfig file.

This enables it for x86-64 (but not 32-bit, we'd need to make sure
cmpxchg() turns into the proper cmpxchg8b in order to enable it for
32-bit mode).
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bc08b449
  3. 24 Jul, 2013 1 commit
  5. 09 Jul, 2013 2 commits
    • Chanho Min's avatar
      lib: add lz4 compressor module · c72ac7a1
      Chanho Min authored 
      This patchset is for supporting LZ4 compression and the crypto API using
it.

As shown below, the size of data is a little bit bigger but compressing
speed is faster under the enabled unaligned memory access.  We can use
lz4 de/compression through crypto API as well.  Also, It will be useful
for another potential user of lz4 compression.

lz4 Compression Benchmark:
Compiler: ARM gcc 4.6.4
ARMv7, 1 GHz based board
   Kernel: linux 3.4
   Uncompressed data Size: 101 MB
         Compressed Size  compression Speed
   LZO   72.1MB		  32.1MB/s, 33.0MB/s(UA)
   LZ4   75.1MB		  30.4MB/s, 35.9MB/s(UA)
   LZ4HC 59.8MB		   2.4MB/s,  2.5MB/s(UA)
- UA: Unaligned memory Access support
- Latest patch set for LZO applied

This patch:

Add support for LZ4 compression in the Linux Kernel.  LZ4 Compression APIs
for kernel are based on LZ4 implementation by Yann Collet and were changed
for kernel coding style.

LZ4 homepage : http://fastcompression.blogspot.com/p/lz4.html
LZ4 source repository : http://code.google.com/p/lz4/
svn revision : r90

Two APIs are added:

lz4_compress() support basic lz4 compression whereas lz4hc_compress()
support high compression or CPU performance get lower but compression
ratio get higher.  Also, we require the pre-allocated working memory with
the defined size and destination buffer must be allocated with the size of
lz4_compressbound.

[akpm@linux-foundation.org: make lz4_compresshcctx() static]
Signed-off-by: default avatarChanho Min <chanho.min@lge.com>
Cc: "Darrick J. Wong" <djwong@us.ibm.com>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Herbert Xu <herbert@gondor.hengli.com.au>
Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Kyungsik Lee <kyungsik.lee@lge.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c72ac7a1
    • Kyungsik Lee's avatar
      lib: add support for LZ4-compressed kernel · e76e1fdf
      Kyungsik Lee authored 
      Add support for extracting LZ4-compressed kernel images, as well as
LZ4-compressed ramdisk images in the kernel boot process.
Signed-off-by: default avatarKyungsik Lee <kyungsik.lee@lge.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      e76e1fdf
  7. 28 Jun, 2013 1 commit
    • Geert Uytterhoeven's avatar
      lib: Move fonts from drivers/video/console/ to lib/fonts/ · ee89bd6b
      Geert Uytterhoeven authored 
      Several drivers need font support independent of CONFIG_VT, cfr. commit
9cbce8d7e1dae0744ca4f68d62aa7de18196b6f4, "console/font: Refactor font
support code selection logic").
Hence move the fonts and their support logic from drivers/video/console/ to
its own library directory lib/fonts/.
This also allows to limit processing of drivers/video/console/Makefile to
CONFIG_VT=y again.

[Kevin Hilman <khilman@linaro.org>: Update arch/arm/boot/compressed/Makefile]
Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
      ee89bd6b
  9. 05 Jun, 2013 1 commit
  11. 20 May, 2013 1 commit
  13. 15 Apr, 2013 1 commit
  15. 17 Jan, 2013 1 commit
  17. 18 Dec, 2012 1 commit
  19. 08 Oct, 2012 1 commit
    • David Howells's avatar
      X.509: Implement simple static OID registry · a77ad6ea
      David Howells authored 
      Implement a simple static OID registry that allows the mapping of an encoded
OID to an enum value for ease of use.

The OID registry index enum appears in the:

	linux/oid_registry.h

header file.  A script generates the registry from lines in the header file
that look like:

	<sp*>OID_foo,<sp*>/*<sp*>1.2.3.4<sp*>*/

The actual OID is taken to be represented by the numbers with interpolated
dots in the comment.

All other lines in the header are ignored.

The registry is queries by calling:

	OID look_up_oid(const void *data, size_t datasize);

This returns a number from the registry enum representing the OID if found or
OID__NR if not.
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
      a77ad6ea
  21. 31 Jul, 2012 1 commit
  23. 23 Jul, 2012 1 commit
    • David Daney's avatar
      of/lib: Allow scripts/dtc/libfdt to be used from kernel code · ab253839
      David Daney authored 
      libfdt is part of the device tree support in scripts/dtc/libfdt.  For
some platforms that use the Device Tree, we want to be able to edit
the flattened device tree form.

We don't want to burden kernel builds that do not require it, so we
gate compilation of libfdt files with CONFIG_LIBFDT.  So if it is
needed, you need to do this in your Kconfig:

	select LIBFDT

And in the Makefile of the code using libfdt something like:

ccflags-y := -I$(src)/../../../scripts/dtc/libfdt
Signed-off-by: default avatarDavid Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: linux-kernel@vger.kernel.org
Acked-by: default avatarRob Herring <rob.herring@calxeda.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
      ab253839
  25. 26 May, 2012 2 commits
  27. 24 May, 2012 1 commit
  29. 02 May, 2012 1 commit
  31. 20 Apr, 2012 1 commit
    • Wolfram Sang's avatar
      lib: add support for stmp-style devices · 4ccf4bea
      Wolfram Sang authored 
      MX23/28 use IP cores which follow a register layout I have first seen on
STMP3xxx SoCs. In this layout, every register actually has four u32:

 1.) to store a value directly
 2.) a SET register where every 1-bit sets the corresponding bit,
     others are unaffected
 3.) same with a CLR register
 4.) same with a TOG (toggle) register

Also, the 2 MSBs in register 0 are always the same and can be used to reset
the IP core.

All this is strictly speaking not mach-specific (but IP core specific) and,
thus, doesn't need to be in mach-mxs/include. At least mx6 also uses IP cores
following this stmp-style. So:

Introduce a stmp-style device, put the code and defines for that in a public
place (lib/), and let drivers for stmp-style devices select that code.
To avoid regressions and ease reviewing, the actual code is simply copied from
mach-mxs. It definately wants updates, but those need a seperate patch series.

Voila, mach dependency gone, reusable code introduced. Note that I didn't
remove the duplicated code from mach-mxs yet, first the drivers have to be
converted.
Signed-off-by: default avatarWolfram Sang <w.sang@pengutronix.de>
Acked-by: default avatarShawn Guo <shawn.guo@linaro.org>
Acked-by: default avatarDong Aisheng <dong.aisheng@linaro.org>
      4ccf4bea
  33. 29 Mar, 2012 1 commit
  35. 24 Mar, 2012 1 commit
    • Richard Weinberger's avatar
      Introduce CONFIG_GENERIC_IO · 087fafd1
      Richard Weinberger authored 
      There are situations where CONFIG_HAS_IOMEM is too restrictive.
For example CONFIG_MTD_NAND_NANDSIM depends on CONFIG_HAS_IOMEM
but it works perfectly fine if an architecture without io memory
just includes asm-generic/io.h or implements everything defined in it.
UML is such a corner case.
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
      087fafd1
  37. 23 Mar, 2012 3 commits
  39. 01 Feb, 2012 1 commit
  41. 31 Jan, 2012 1 commit
  43. 17 Jan, 2012 4 commits
  45. 29 Nov, 2011 1 commit
    • Tom Herbert's avatar
      dql: Dynamic queue limits · 75957ba3
      Tom Herbert authored 
      Implementation of dynamic queue limits (dql).  This is a libary which
allows a queue limit to be dynamically managed.  The goal of dql is
to set the queue limit, number of objects to the queue, to be minimized
without allowing the queue to be starved.

dql would be used with a queue which has these properties:

1) Objects are queued up to some limit which can be expressed as a
   count of objects.
2) Periodically a completion process executes which retires consumed
   objects.
3) Starvation occurs when limit has been reached, all queued data has
   actually been consumed but completion processing has not yet run,
   so queuing new data is blocked.
4) Minimizing the amount of queued data is desirable.

A canonical example of such a queue would be a NIC HW transmit queue.

The queue limit is dynamic, it will increase or decrease over time
depending on the workload.  The queue limit is recalculated each time
completion processing is done.  Increases occur when the queue is
starved and can exponentially increase over successive intervals.
Decreases occur when more data is being maintained in the queue than
needed to prevent starvation.  The number of extra objects, or "slack",
is measured over successive intervals, and to avoid hysteresis the
limit is only reduced by the miminum slack seen over a configurable
time period.

dql API provides routines to manage the queue:
- dql_init is called to intialize the dql structure
- dql_reset is called to reset dynamic values
- dql_queued called when objects are being enqueued
- dql_avail returns availability in the queue
- dql_completed is called when objects have be consumed in the queue

Configuration consists of:
- max_limit, maximum limit
- min_limit, minimum limit
- slack_hold_time, time to measure instances of slack before reducing
  queue limit
Signed-off-by: default avatarTom Herbert <therbert@google.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      75957ba3
  47. 28 Nov, 2011 1 commit
  49. 24 Nov, 2011 1 commit
  51. 21 Nov, 2011 1 commit
    • Dmitry Kasatkin's avatar
      digsig: build dependency fix · de353533
      Dmitry Kasatkin authored 
      Fix build errors by adding Kconfig dependency on KEYS.
CRYPTO dependency removed.

  CC      security/integrity/digsig.o
security/integrity/digsig.c: In function ?integrity_digsig_verify?:
security/integrity/digsig.c:38:4: error: implicit declaration of function ?request_key?
security/integrity/digsig.c:38:17: error: ?key_type_keyring? undeclared (first use in this function)
security/integrity/digsig.c:38:17: note: each undeclared identifier is reported only once for each function it appears in
make[2]: *** [security/integrity/digsig.o] Error 1
Reported-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
      de353533
  53. 09 Nov, 2011 3 commits
    • Dmitry Kasatkin's avatar
      crypto: digital signature verification support · 051dbb91
      Dmitry Kasatkin authored 
      This patch implements RSA digital signature verification using GnuPG library.

The format of the signature and the public key is defined by their respective
headers. The signature header contains version information, algorithm,
and keyid, which was used to generate the signature.
The key header contains version and algorythim type.
The payload of the signature and the key are multi-precision integers.

The signing and key management utilities evm-utils provide functionality
to generate signatures and load keys into the kernel keyring.
When the key is added to the kernel keyring, the keyid defines the name
of the key.
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Acked-by: default avatarMimi Zohar <zohar@us.ibm.com>
      051dbb91
    • Dmitry Kasatkin's avatar
      crypto: GnuPG based MPI lib - additional sources (part 4) · 7e8dec91
      Dmitry Kasatkin authored 
      Adds the multi-precision-integer maths library which was originally taken
from GnuPG and ported to the kernel by (among others) David Howells.
This version is taken from Fedora kernel 2.6.32-71.14.1.el6.
The difference is that checkpatch reported errors and warnings have been fixed.

This library is used to implemenet RSA digital signature verification
used in IMA/EVM integrity protection subsystem.

Due to patch size limitation, the patch is divided into 4 parts.

This code is unnecessary for RSA digital signature verification,
but for completeness it is included here and can be compiled,
if CONFIG_MPILIB_EXTRA is enabled.
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      7e8dec91
    • Dmitry Kasatkin's avatar
      crypto: GnuPG based MPI lib - make files (part 3) · d9c46b18
      Dmitry Kasatkin authored 
      Adds the multi-precision-integer maths library which was originally taken
from GnuPG and ported to the kernel by (among others) David Howells.
This version is taken from Fedora kernel 2.6.32-71.14.1.el6.
The difference is that checkpatch reported errors and warnings have been fixed.

This library is used to implemenet RSA digital signature verification
used in IMA/EVM integrity protection subsystem.

Due to patch size limitation, the patch is divided into 4 parts.
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      d9c46b18
  55. 29 Oct, 2011 3 commits
  57. 04 Oct, 2011 1 commit
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7