kernel-packages team mailing list archive

[Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>]

Thank you for providing a patch, and making Ubuntu better.

Can you provide some information on the status of the patch with regards
to getting it merged upstream? Has it been sent upstream, what sort of
feedback has it received, is it getting applied to a subsystem
maintainer's tree, etc?

People affected by this bug are probably wondering why the kernel team
doesn't just apply the patch and fix it. The reason is that the kernel
team is reluctant (not opposed) to apply any patch to a stable kernel
that is not from upstream. Applying patches that don't come from
upstream add greatly to the support of the kernel as other upstream
patches may touch the same area as the non-upstream patch and may
prevent them from applying cleanly.

To submit your patch, send your patch with the detailed
description/changelog and your Signoff (ending with Signed-off-by: your
name <email>), to the emails listed from ./scripts/get_maintainer.pl
drivers/SUBSYSTEM-DETAILS (the get_maintainer.pl is from the kernel
sources). Once you have sent the patch upstream and it's accepted,
please drop a note here so that we can cherry-pick/include the patch
into Ubuntu kernel.

** Changed in: linux (Ubuntu)
   Importance: Undecided => Medium

** Changed in: linux (Ubuntu)
       Status: Confirmed => Triaged

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https://bugs.launchpad.net/bugs/1594960

Title:
  On queued_spin_lock function issue.

Status in linux package in Ubuntu:
  Triaged

Bug description:
  On this function stall 100 cycles

  +++ b/include/asm-generic/qspinlock.h
  @@ -102,7 +102,7 @@ static __always_inline void queued_spin_lock(struct qspinlock *lock)
          u32 val;
   
          val = atomic_cmpxchg_acquire(&lock->val, 0, _Q_LOCKED_VAL);
  -       if (likely(val == 0))
  +       if (likely(!val))
                  return;
          queued_spin_lock_slowpath(lock, val);
   }
  With this patch vas reduced on 20 cycles on perf.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: linux-image-4.4.0-24-generic 4.4.0-24.43
  ProcVersionSignature: Ubuntu 4.4.0-24.43-generic 4.4.10
  Uname: Linux 4.4.0-24-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.1
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  asu        3254 F.... pulseaudio
  CurrentDesktop: MATE
  Date: Tue Jun 21 23:16:49 2016
  InstallationDate: Installed on 2016-04-29 (53 days ago)
  InstallationMedia: Ubuntu-Studio 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
  IwConfig:
   lo        no wireless extensions.
   
   enp1s0    no wireless extensions.
  MachineType: Olidata S.p.A. ALABAMA
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-24-generic root=/dev/mapper/192--168--0--108--vg-root ro
  RelatedPackageVersions:
   linux-restricted-modules-4.4.0-24-generic N/A
   linux-backports-modules-4.4.0-24-generic  N/A
   linux-firmware                            1.157
  RfKill:
   
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 07/08/2008
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: S0101
  dmi.board.asset.tag: To Be Filled By O.E.M.
  dmi.board.name: To be filled by O.E.M.
  dmi.board.vendor: To be filled by O.E.M.
  dmi.board.version: To be filled by O.E.M.
  dmi.chassis.asset.tag: To Be Filled By O.E.M.
  dmi.chassis.type: 3
  dmi.chassis.vendor: To Be Filled By O.E.M.
  dmi.chassis.version: To Be Filled By O.E.M.
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrS0101:bd07/08/2008:svnOlidataS.p.A.:pnALABAMA:pvrToBeFilledByO.E.M.:rvnTobefilledbyO.E.M.:rnTobefilledbyO.E.M.:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.E.M.:
  dmi.product.name: ALABAMA
  dmi.product.version: To Be Filled By O.E.M.
  dmi.sys.vendor: Olidata S.p.A.

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