1. 23 7月, 2013 2 次提交
  2. 20 7月, 2013 2 次提交
  3. 19 7月, 2013 1 次提交
    • E
      vlan: mask vlan prio bits · d4b812de
      Eric Dumazet 提交于
      In commit 48cc32d3
      ("vlan: don't deliver frames for unknown vlans to protocols")
      Florian made sure we set pkt_type to PACKET_OTHERHOST
      if the vlan id is set and we could find a vlan device for this
      particular id.
      
      But we also have a problem if prio bits are set.
      
      Steinar reported an issue on a router receiving IPv6 frames with a
      vlan tag of 4000 (id 0, prio 2), and tunneled into a sit device,
      because skb->vlan_tci is set.
      
      Forwarded frame is completely corrupted : We can see (8100:4000)
      being inserted in the middle of IPv6 source address :
      
      16:48:00.780413 IP6 2001:16d8:8100:4000:ee1c:0:9d9:bc87 >
      9f94:4d95:2001:67c:29f4::: ICMP6, unknown icmp6 type (0), length 64
             0x0000:  0000 0029 8000 c7c3 7103 0001 a0ae e651
             0x0010:  0000 0000 ccce 0b00 0000 0000 1011 1213
             0x0020:  1415 1617 1819 1a1b 1c1d 1e1f 2021 2223
             0x0030:  2425 2627 2829 2a2b 2c2d 2e2f 3031 3233
      
      It seems we are not really ready to properly cope with this right now.
      
      We can probably do better in future kernels :
      vlan_get_ingress_priority() should be a netdev property instead of
      a per vlan_dev one.
      
      For stable kernels, lets clear vlan_tci to fix the bugs.
      Reported-by: NSteinar H. Gunderson <sesse@google.com>
      Signed-off-by: NEric Dumazet <edumazet@google.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      d4b812de
  4. 18 7月, 2013 2 次提交
    • R
      ACPI / video / i915: No ACPI backlight if firmware expects Windows 8 · 8c5bd7ad
      Rafael J. Wysocki 提交于
      According to Matthew Garrett, "Windows 8 leaves backlight control up
      to individual graphics drivers rather than making ACPI calls itself.
      There's plenty of evidence to suggest that the Intel driver for
      Windows [8] doesn't use the ACPI interface, including the fact that
      it's broken on a bunch of machines when the OS claims to support
      Windows 8.  The simplest thing to do appears to be to disable the
      ACPI backlight interface on these systems".
      
      There's a problem with that approach, however, because simply
      avoiding to register the ACPI backlight interface if the firmware
      calls _OSI for Windows 8 may not work in the following situations:
       (1) The ACPI backlight interface actually works on the given system
           and the i915 driver is not loaded (e.g. another graphics driver
           is used).
       (2) The ACPI backlight interface doesn't work on the given system,
           but there is a vendor platform driver that will register its
           own, equally broken, backlight interface if not prevented from
           doing so by the ACPI subsystem.
      Therefore we need to allow the ACPI backlight interface to be
      registered until the i915 driver is loaded which then will unregister
      it if the firmware has called _OSI for Windows 8 (or will register
      the ACPI video driver without backlight support if not already
      present).
      
      For this reason, introduce an alternative function for registering
      ACPI video, acpi_video_register_with_quirks(), that will check
      whether or not the ACPI video driver has already been registered
      and whether or not the backlight Windows 8 quirk has to be applied.
      If the quirk has to be applied, it will block the ACPI backlight
      support and either unregister the backlight interface if the ACPI
      video driver has already been registered, or register the ACPI
      video driver without the backlight interface otherwise.  Make
      the i915 driver use acpi_video_register_with_quirks() instead of
      acpi_video_register() in i915_driver_load().
      
      This change is based on earlier patches from Matthew Garrett,
      Chun-Yi Lee and Seth Forshee and includes a fix from Aaron Lu's.
      
      References: https://bugzilla.kernel.org/show_bug.cgi?id=51231Tested-by: NAaron Lu <aaron.lu@intel.com>
      Tested-by: NIgor Gnatenko <i.gnatenko.brain@gmail.com>
      Tested-by: NYves-Alexis Perez <corsac@debian.org>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      Reviewed-by: NAaron Lu <aaron.lu@intel.com>
      Acked-by: NMatthew Garrett <matthew.garrett@nebula.com>
      8c5bd7ad
    • A
      ACPICA: expose OSI version · 242b2287
      Aaron Lu 提交于
      Expose acpi_gbl_osi_data so that code outside of ACPICA can check
      the value of the last successfull _OSI call.  The definitions for
      OSI versions are moved to actypes.h so that other components can
      access them too.
      
      Based on a patch from Matthew Garrett which in turn was based on
      an earlier patch from Seth Forshee.
      
      [rjw: Changelog]
      Signed-off-by: NAaron Lu <aaron.lu@intel.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      242b2287
  5. 17 7月, 2013 10 次提交
  6. 15 7月, 2013 2 次提交
  7. 14 7月, 2013 1 次提交
  8. 13 7月, 2013 4 次提交
  9. 12 7月, 2013 2 次提交
  10. 11 7月, 2013 6 次提交
    • M
      mm: remove free_area_cache · 98d1e64f
      Michel Lespinasse 提交于
      Since all architectures have been converted to use vm_unmapped_area(),
      there is no remaining use for the free_area_cache.
      Signed-off-by: NMichel Lespinasse <walken@google.com>
      Acked-by: NRik van Riel <riel@redhat.com>
      Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
      Cc: "Luck, Tony" <tony.luck@intel.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: David Howells <dhowells@redhat.com>
      Cc: Helge Deller <deller@gmx.de>
      Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
      Cc: Matt Turner <mattst88@gmail.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Richard Henderson <rth@twiddle.net>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      98d1e64f
    • S
      zbud: add to mm/ · 4e2e2770
      Seth Jennings 提交于
      zbud is an special purpose allocator for storing compressed pages.  It
      is designed to store up to two compressed pages per physical page.
      While this design limits storage density, it has simple and
      deterministic reclaim properties that make it preferable to a higher
      density approach when reclaim will be used.
      
      zbud works by storing compressed pages, or "zpages", together in pairs
      in a single memory page called a "zbud page".  The first buddy is "left
      justifed" at the beginning of the zbud page, and the last buddy is
      "right justified" at the end of the zbud page.  The benefit is that if
      either buddy is freed, the freed buddy space, coalesced with whatever
      slack space that existed between the buddies, results in the largest
      possible free region within the zbud page.
      
      zbud also provides an attractive lower bound on density.  The ratio of
      zpages to zbud pages can not be less than 1.  This ensures that zbud can
      never "do harm" by using more pages to store zpages than the
      uncompressed zpages would have used on their own.
      
      This implementation is a rewrite of the zbud allocator internally used
      by zcache in the driver/staging tree.  The rewrite was necessary to
      remove some of the zcache specific elements that were ingrained
      throughout and provide a generic allocation interface that can later be
      used by zsmalloc and others.
      
      This patch adds zbud to mm/ for later use by zswap.
      Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
      Acked-by: NRik van Riel <riel@redhat.com>
      Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
      Cc: Nitin Gupta <ngupta@vflare.org>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
      Cc: Robert Jennings <rcj@linux.vnet.ibm.com>
      Cc: Jenifer Hopper <jhopper@us.ibm.com>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Johannes Weiner <jweiner@redhat.com>
      Cc: Larry Woodman <lwoodman@redhat.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Dave Hansen <dave@sr71.net>
      Cc: Joe Perches <joe@perches.com>
      Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
      Cc: Cody P Schafer <cody@linux.vnet.ibm.com>
      Cc: Hugh Dickens <hughd@google.com>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Bob Liu <bob.liu@oracle.com>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4e2e2770
    • E
      net: rename busy poll socket op and globals · 64b0dc51
      Eliezer Tamir 提交于
      Rename LL_SO to BUSY_POLL_SO
      Rename sysctl_net_ll_{read,poll} to sysctl_busy_{read,poll}
      Fix up users of these variables.
      Fix documentation for sysctl.
      
      a patch for the socket.7  man page will follow separately,
      because of limitations of my mail setup.
      Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      64b0dc51
    • E
      net: rename ll methods to busy-poll · 8b80cda5
      Eliezer Tamir 提交于
      Rename ndo_ll_poll to ndo_busy_poll.
      Rename sk_mark_ll to sk_mark_napi_id.
      Rename skb_mark_ll to skb_mark_napi_id.
      Correct all useres of these functions.
      Update comments and defines  in include/net/busy_poll.h
      Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      8b80cda5
    • E
      net: rename include/net/ll_poll.h to include/net/busy_poll.h · 076bb0c8
      Eliezer Tamir 提交于
      Rename the file and correct all the places where it is included.
      Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      076bb0c8
    • M
      dm: optimize use SRCU and RCU · 83d5e5b0
      Mikulas Patocka 提交于
      This patch removes "io_lock" and "map_lock" in struct mapped_device and
      "holders" in struct dm_table and replaces these mechanisms with
      sleepable-rcu.
      
      Previously, the code would call "dm_get_live_table" and "dm_table_put" to
      get and release table. Now, the code is changed to call "dm_get_live_table"
      and "dm_put_live_table". dm_get_live_table locks sleepable-rcu and
      dm_put_live_table unlocks it.
      
      dm_get_live_table_fast/dm_put_live_table_fast can be used instead of
      dm_get_live_table/dm_put_live_table. These *_fast functions use
      non-sleepable RCU, so the caller must not block between them.
      
      If the code changes active or inactive dm table, it must call
      dm_sync_table before destroying the old table.
      Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
      Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
      Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      83d5e5b0
  11. 10 7月, 2013 8 次提交
    • S
      NFS: Make nfs_attribute_cache_expired() non-static · 43f291cd
      Scott Mayhew 提交于
      NFS: Make nfs_attribute_cache_expired() non-static so we can call it from
      nfs_readdir().
      Signed-off-by: NScott Mayhew <smayhew@redhat.com>
      Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      43f291cd
    • M
      virtio: support unlocked queue poll · cc229884
      Michael S. Tsirkin 提交于
      This adds a way to check ring empty state after enable_cb outside any
      locks. Will be used by virtio_net.
      
      Note: there's room for more optimization: caller is likely to have a
      memory barrier already, which means we might be able to get rid of a
      barrier here.  Deferring this optimization until we do some
      benchmarking.
      Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      cc229884
    • E
      net/fs: change busy poll time accounting · 76b1e9b9
      Eliezer Tamir 提交于
      Suggested by Linus:
      Changed time accounting for busy-poll:
      - Make it microsecond based.
      - Use unsigned longs.
      - Revert back to use time_after instead of time_in_range.
      Reorder poll/select busy loop conditions:
      - Clear busy_flag after one time we can't busy-poll.
      - Only init busy_end if we actually are going to busy-poll.
      Added one more missing need_resched() test.
      Signed-off-by: NEliezer Tamir <eliezer.tamir@linux.intel.com>
      Signed-off-by: NDavid S. Miller <davem@davemloft.net>
      76b1e9b9
    • J
      libceph: fix invalid unsigned->signed conversion for timespec encoding · 8b8cf891
      Josh Durgin 提交于
      __kernel_time_t is a long, which cannot hold a U32_MAX on 32-bit
      architectures.  Just drop this check as it has limited value.
      
      This fixes a crash like:
      
      [  957.905812] kernel BUG at /srv/autobuild-ceph/gitbuilder.git/build/include/linux/ceph/decode.h:164!
      [  957.914849] Internal error: Oops - BUG: 0 [#1] SMP ARM
      [  957.919978] Modules linked in: rbd libceph libcrc32c ipmi_devintf ipmi_si ipmi_msghandler nfsd nfs_acl auth_rpcgss nfs fscache lockd sunrpc
      [  957.932547] CPU: 1    Tainted: G        W     (3.9.0-ceph-19bb6a83-highbank #1)
      [  957.939881] PC is at ceph_osdc_build_request+0x8c/0x4f8 [libceph]
      [  957.945967] LR is at 0xec520904
      [  957.949103] pc : [<bf13e76c>]    lr : [<ec520904>]    psr: 20000153
      [  957.949103] sp : ec753df8  ip : 00000001  fp : ec53e100
      [  957.960571] r10: ebef25c0  r9 : ec5fa400  r8 : ecbcc000
      [  957.965788] r7 : 00000000  r6 : 00000000  r5 : ffffffff  r4 : 00000020
      [  957.972307] r3 : 51cc8143  r2 : ec520900  r1 : ec753e58  r0 : ec520908
      [  957.978827] Flags: nzCv  IRQs on  FIQs off  Mode SVC_32  ISA ARM  Segment user
      [  957.986039] Control: 10c5387d  Table: 2c59c04a  DAC: 00000015
      [  957.991777] Process rbd (pid: 2138, stack limit = 0xec752238)
      [  957.997514] Stack: (0xec753df8 to 0xec754000)
      [  958.001864] 3de0:                                                       00000001 00000001
      [  958.010032] 3e00: 00000001 bf139744 ecbcc000 ec55a0a0 00000024 00000000 ebef25c0 fffffffe
      [  958.018204] 3e20: ffffffff 00000000 00000000 00000001 ec5fa400 ebef25c0 ec53e100 bf166b68
      [  958.026377] 3e40: 00000000 0000220f fffffffe ffffffff ec753e58 bf13ff24 51cc8143 05b25ed2
      [  958.034548] 3e60: 00000001 00000000 00000000 bf1688d4 00000001 00000000 00000000 00000000
      [  958.042720] 3e80: 00000001 00000060 ec5fa400 ed53d200 ed439600 ed439300 00000001 00000060
      [  958.050888] 3ea0: ec5fa400 ed53d200 00000000 bf16a320 00000000 ec53e100 00000040 ec753eb8
      [  958.059059] 3ec0: ec51df00 ed53d7c0 ed53d200 ed53d7c0 00000000 ed53d7c0 ec5fa400 bf16ed70
      [  958.067230] 3ee0: 00000000 00000060 00000002 ed53d200 00000000 bf16acf4 ed53d7c0 ec752000
      [  958.075402] 3f00: ed980e50 e954f5d8 00000000 00000060 ed53d240 ed53d258 ec753f80 c04f44a8
      [  958.083574] 3f20: edb7910c ec664700 01ade920 c02e4c44 00000060 c016b3dc ec51de40 01adfb84
      [  958.091745] 3f40: 00000060 ec752000 ec753f80 ec752000 00000060 c0108444 00000007 ec51de48
      [  958.099914] 3f60: ed0eb8c0 00000000 00000000 ec51de40 01adfb84 00000001 00000060 c0108858
      [  958.108085] 3f80: 00000000 00000000 51cc8143 00000060 01adfb84 00000007 00000004 c000dd68
      [  958.116257] 3fa0: 00000000 c000dbc0 00000060 01adfb84 00000007 01adfb84 00000060 01adfb80
      [  958.124429] 3fc0: 00000060 01adfb84 00000007 00000004 beded1a8 00000000 01adf2f0 01ade920
      [  958.132599] 3fe0: 00000000 beded180 b6811324 b6811334 800f0010 00000007 2e7f5821 2e7f5c21
      [  958.140815] [<bf13e76c>] (ceph_osdc_build_request+0x8c/0x4f8 [libceph]) from [<bf166b68>] (rbd_osd_req_format_write+0x50/0x7c [rbd])
      [  958.152739] [<bf166b68>] (rbd_osd_req_format_write+0x50/0x7c [rbd]) from [<bf1688d4>] (rbd_dev_header_watch_sync+0xe0/0x204 [rbd])
      [  958.164486] [<bf1688d4>] (rbd_dev_header_watch_sync+0xe0/0x204 [rbd]) from [<bf16a320>] (rbd_dev_image_probe+0x23c/0x850 [rbd])
      [  958.175967] [<bf16a320>] (rbd_dev_image_probe+0x23c/0x850 [rbd]) from [<bf16acf4>] (rbd_add+0x3c0/0x918 [rbd])
      [  958.185975] [<bf16acf4>] (rbd_add+0x3c0/0x918 [rbd]) from [<c02e4c44>] (bus_attr_store+0x20/0x2c)
      [  958.194850] [<c02e4c44>] (bus_attr_store+0x20/0x2c) from [<c016b3dc>] (sysfs_write_file+0x168/0x198)
      [  958.203984] [<c016b3dc>] (sysfs_write_file+0x168/0x198) from [<c0108444>] (vfs_write+0x9c/0x170)
      [  958.212768] [<c0108444>] (vfs_write+0x9c/0x170) from [<c0108858>] (sys_write+0x3c/0x70)
      [  958.220768] [<c0108858>] (sys_write+0x3c/0x70) from [<c000dbc0>] (ret_fast_syscall+0x0/0x30)
      [  958.229199] Code: e59d1058 e5913000 e3530000 ba000114 (e7f001f2)
      
      CC: stable@vger.kernel.org  # 3.4+
      Signed-off-by: NJosh Durgin <josh.durgin@inktank.com>
      Reviewed-by: NSage Weil <sage@inktank.com>
      8b8cf891
    • A
      lib/scatterlist: introduce sg_pcopy_from_buffer() and sg_pcopy_to_buffer() · df642cea
      Akinobu Mita 提交于
      The only difference between sg_pcopy_{from,to}_buffer() and
      sg_copy_{from,to}_buffer() is an additional argument that specifies the
      number of bytes to skip the SG list before copying.
      Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
      Cc: "David S. Miller" <davem@davemloft.net>
      Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
      Cc: Douglas Gilbert <dgilbert@interlog.com>
      Cc: Herbert Xu <herbert@gondor.apana.org.au>
      Cc: Horia Geanta <horia.geanta@freescale.com>
      Cc: Imre Deak <imre.deak@intel.com>
      Acked-by: NTejun Heo <tj@kernel.org>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      df642cea
    • C
      lib: add lz4 compressor module · c72ac7a1
      Chanho Min 提交于
      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: NChanho 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: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      c72ac7a1
    • K
      lib: add support for LZ4-compressed kernel · e76e1fdf
      Kyungsik Lee 提交于
      Add support for extracting LZ4-compressed kernel images, as well as
      LZ4-compressed ramdisk images in the kernel boot process.
      Signed-off-by: NKyungsik 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: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      e76e1fdf
    • K
      decompressor: add LZ4 decompressor module · cffb78b0
      Kyungsik Lee 提交于
      Add support for LZ4 decompression in the Linux Kernel.  LZ4 Decompression
      APIs for kernel are based on LZ4 implementation by Yann Collet.
      
      Benchmark Results(PATCH v3)
      Compiler: Linaro ARM gcc 4.6.2
      
      1. ARMv7, 1.5GHz based board
         Kernel: linux 3.4
         Uncompressed Kernel Size: 14MB
              Compressed Size  Decompression Speed
         LZO  6.7MB            20.1MB/s, 25.2MB/s(UA)
         LZ4  7.3MB            29.1MB/s, 45.6MB/s(UA)
      
      2. ARMv7, 1.7GHz based board
         Kernel: linux 3.7
         Uncompressed Kernel Size: 14MB
              Compressed Size  Decompression Speed
         LZO  6.0MB            34.1MB/s, 52.2MB/s(UA)
         LZ4  6.5MB            86.7MB/s
      - UA: Unaligned memory Access support
      - Latest patch set for LZO applied
      
      This patch set is for adding support for LZ4-compressed Kernel.  LZ4 is a
      very fast lossless compression algorithm and it also features an extremely
      fast decoder [1].
      
      But we have five of decompressors already and one question which does
      arise, however, is that of where do we stop adding new ones?  This issue
      had been discussed and came to the conclusion [2].
      
      Russell King said that we should have:
      
       - one decompressor which is the fastest
       - one decompressor for the highest compression ratio
       - one popular decompressor (eg conventional gzip)
      
      If we have a replacement one for one of these, then it should do exactly
      that: replace it.
      
      The benchmark shows that an 8% increase in image size vs a 66% increase
      in decompression speed compared to LZO(which has been known as the
      fastest decompressor in the Kernel).  Therefore the "fast but may not be
      small" compression title has clearly been taken by LZ4 [3].
      
      [1] http://code.google.com/p/lz4/
      [2] http://thread.gmane.org/gmane.linux.kbuild.devel/9157
      [3] http://thread.gmane.org/gmane.linux.kbuild.devel/9347
      
      LZ4 homepage: http://fastcompression.blogspot.com/p/lz4.html
      LZ4 source repository: http://code.google.com/p/lz4/Signed-off-by: NKyungsik Lee <kyungsik.lee@lge.com>
      Signed-off-by: NYann Collet <yann.collet.73@gmail.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>
      Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cffb78b0