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  1. 03 Feb, 2013 1 commit
  3. 31 Jan, 2013 1 commit
  5. 27 Jan, 2013 1 commit
    • Frederic Weisbecker's avatar
      cputime: Avoid multiplication overflow on utime scaling · 62188451
      Frederic Weisbecker authored 
      We scale stime, utime values based on rtime (sum_exec_runtime
converted to jiffies). During scaling we multiple rtime * utime,
which seems to be fine, since both values are converted to u64,
but it's not.

Let assume HZ is 1000 - 1ms tick. Process consist of 64 threads,
run for 1 day, threads utilize 100% cpu on user space. Machine
has 64 cpus.

Process rtime = utime will be 64 * 24 * 60 * 60 * 1000 jiffies,
which is 0x149970000. Multiplication rtime * utime result is
0x1a855771100000000, which can not be covered in 64 bits.

Result of overflow is stall of utime values visible in user
space (prev_utime in kernel), even if application still consume
lot of CPU time.

A solution to solve this is to perform the multiplication on
stime instead of utime. It's easy to grow the utime value fast
with a CPU bound thread in userspace for example. Now we assume
that doing so with stime is much harder. In most cases a task
shouldn't ever spend much time in kernel space as it tends to
sleep waiting for jobs completion when they take long to
achieve. IO is the typical example of that.

Hence scaling the cputime by performing the multiplication on
stime instead of utime should considerably reduce the chances of
an overflow on most workloads.

This is largely inspired by a patch from Stanislaw Gruszka:
http://lkml.kernel.org/r/20130107113144.GA7544@redhat.comInspired-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Reported-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Acked-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1359217182-25184-1-git-send-email-fweisbec@gmail.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      62188451
  7. 25 Jan, 2013 1 commit
    • Ying Xue's avatar
      sched/rt: Avoid updating RT entry timeout twice within one tick period · 57d2aa00
      Ying Xue authored 
      The issue below was found in 2.6.34-rt rather than mainline rt
kernel, but the issue still exists upstream as well.

So please let me describe how it was noticed on 2.6.34-rt:

On this version, each softirq has its own thread, it means there
is at least one RT FIFO task per cpu. The priority of these
tasks is set to 49 by default. If user launches an RT FIFO task
with priority lower than 49 of softirq RT tasks, it's possible
there are two RT FIFO tasks enqueued one cpu runqueue at one
moment. By current strategy of balancing RT tasks, when it comes
to RT tasks, we really need to put them off to a CPU that they
can run on as soon as possible. Even if it means a bit of cache
line flushing, we want RT tasks to be run with the least latency.

When the user RT FIFO task which just launched before is
running, the sched timer tick of the current cpu happens. In this
tick period, the timeout value of the user RT task will be
updated once. Subsequently, we try to wake up one softirq RT
task on its local cpu. As the priority of current user RT task
is lower than the softirq RT task, the current task will be
preempted by the higher priority softirq RT task. Before
preemption, we check to see if current can readily move to a
different cpu. If so, we will reschedule to allow the RT push logic
to try to move current somewhere else. Whenever the woken
softirq RT task runs, it first tries to migrate the user FIFO RT
task over to a cpu that is running a task of lesser priority. If
migration is done, it will send a reschedule request to the found
cpu by IPI interrupt. Once the target cpu responds the IPI
interrupt, it will pick the migrated user RT task to preempt its
current task. When the user RT task is running on the new cpu,
the sched timer tick of the cpu fires. So it will tick the user
RT task again. This also means the RT task timeout value will be
updated again. As the migration may be done in one tick period,
it means the user RT task timeout value will be updated twice
within one tick.

If we set a limit on the amount of cpu time for the user RT task
by setrlimit(RLIMIT_RTTIME), the SIGXCPU signal should be posted
upon reaching the soft limit.

But exactly when the SIGXCPU signal should be sent depends on the
RT task timeout value. In fact the timeout mechanism of sending
the SIGXCPU signal assumes the RT task timeout is increased once
every tick.

However, currently the timeout value may be added twice per
tick. So it results in the SIGXCPU signal being sent earlier
than expected.

To solve this issue, we prevent the timeout value from increasing
twice within one tick time by remembering the jiffies value of
last updating the timeout. As long as the RT task's jiffies is
different with the global jiffies value, we allow its timeout to
be updated.
Signed-off-by: default avatarYing Xue <ying.xue@windriver.com>
Signed-off-by: default avatarFan Du <fan.du@windriver.com>
Reviewed-by: default avatarYong Zhang <yong.zhang0@gmail.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1342508623-2887-1-git-send-email-ying.xue@windriver.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      57d2aa00
  9. 24 Jan, 2013 7 commits
  11. 23 Jan, 2013 10 commits
    • Greg Kroah-Hartman's avatar
      MAINTAINERS: Someone needs to watch over the serial drivers · 5e30bbb7
      Greg Kroah-Hartman authored 
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      5e30bbb7
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k · 248152b6
      Linus Torvalds authored 
      Pull m68k fixes from Geert Uytterhoeven:
 "The asm-generic changeset has been ack'ed by Arnd."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k: Wire up finit_module
  asm-generic/dma-mapping-broken.h: Provide dma_alloc_attrs()/dma_free_attrs()
  m68k: Provide dma_alloc_attrs()/dma_free_attrs()
      248152b6
    • Linus Torvalds's avatar
      Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64 · c1b84144
      Linus Torvalds authored 
      Pull arm64 fixes from Catalin Marinas:
 - ELF coredump fix (more registers dumped than what user space expects)
 - SUBARCH name generation (s/aarch64/arm64/)

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64:
  arm64: makefile: fix uname munging when setting ARCH on native machine
  arm64: elf: fix core dumping to match what glibc expects
      c1b84144
    • Alan Stern's avatar
      USB: EHCI: fix build error in ehci-mxc · dba63b2f
      Alan Stern authored 
      This patch (as1643b) fixes a build error in ehci-hcd when compiling for
ARM with allmodconfig:

drivers/usb/host/ehci-hcd.c:1285:0: warning: "PLATFORM_DRIVER" redefined [enabled by default]
drivers/usb/host/ehci-hcd.c:1255:0: note: this is the location of the previous definition
drivers/usb/host/ehci-mxc.c:280:31: warning: 'ehci_mxc_driver' defined but not used [-Wunused-variable]
drivers/usb/host/ehci-hcd.c:1285:0: warning: "PLATFORM_DRIVER" redefined [enabled by default]
drivers/usb/host/ehci-hcd.c:1255:0: note: this is the location of the previous definition

The fix is to convert ehci-mxc over to the new "ehci-hcd is a library"
scheme so that it can coexist peacefully with the ehci-platform
driver.  As part of the conversion the ehci_mxc_priv data structure,
which was allocated dynamically, is now placed where it belongs: in
the private area at the end of struct ehci_hcd.
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Tested-by: default avatarShawn Guo <shawn.guo@linaro.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      dba63b2f
    • Linus Torvalds's avatar
      Merge tag 'sound-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound · db233669
      Linus Torvalds authored 
      Pull sound fixes from Takashi Iwai:
 "Only a few small HD-audio fixes:
   - Addition of new Conexant codec IDs
   - Two one-liners to add fixups for Realtek codecs
   - A last-minute regression fix for auto-mute with power-saving mode
     (regressed since 3.8-rc1)"

* tag 'sound-3.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - Fix inconsistent pin states after resume
  ALSA: hda - Add Conexant CX20755/20756/20757 codec IDs
  ALSA: hda - Add fixup for Acer AO725 laptop
  ALSA: hda - Fix mute led for another HP machine
      db233669
    • Alan Cox's avatar
      MAINTAINERS: remove me · 6d26b3a1
      Alan Cox authored 
      Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      6d26b3a1
    • Takashi Iwai's avatar
      ALSA: hda - Fix inconsistent pin states after resume · 31614bb8
      Takashi Iwai authored 
      The commit [26a6cb6c: ALSA: hda - Implement a poll loop for jacks as a
module parameter] introduced the polling jack detection code, but it
also moved the call of snd_hda_jack_set_dirty_all() in the resume path
after resume/init ops call.  This caused a regression when the jack
state has been changed during power-down (e.g. in the power save
mode).  Since the driver doesn't probe the new jack state but keeps
using the cached value due to no dirty flag, the pin state remains
also as if the jack is still plugged.

The fix is simply moving snd_hda_jack_set_dirty_all() to the original
position.
Reported-by: default avatarManolo Díaz <diaz.manolo@gmail.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
      31614bb8
    • Luciano Coelho's avatar
      Revert "drivers/misc/ti-st: remove gpio handling" · a7e2ca17
      Luciano Coelho authored 
      This reverts commit eccf2979.

The reason is that it broke TI WiLink shared transport on Panda.
Also, callback functions should not be added to board files anymore,
so revert to implementing the power functions in the driver itself.

Additionally, changed a variable name ('status' to 'err') so that this
revert compiles properly.

Cc: stable <stable@vger.kernel.org> [3.7]
Acked-by: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarLuciano Coelho <coelho@ti.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      a7e2ca17
    • Linus Torvalds's avatar
      Merge tag '3.8-pci-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci · 1d854908
      Linus Torvalds authored 
      Pull PCI updates from Bjorn Helgaas:
 "The most important is a fix for a pciehp deadlock that occurs when
  unplugging a Thunderbolt adapter.  We also applied the same fix to
  shpchp, removed CONFIG_EXPERIMENTAL dependencies, fixed a
  pcie_aspm=force problem, and fixed a refcount leak.

  Details:

   - Hotplug
      PCI: pciehp: Use per-slot workqueues to avoid deadlock
      PCI: shpchp: Make shpchp_wq non-ordered
      PCI: shpchp: Handle push button event asynchronously
      PCI: shpchp: Use per-slot workqueues to avoid deadlock

   - Power management
      PCI: Allow pcie_aspm=force even when FADT indicates it is unsupported

   - Misc
      PCI/AER: pci_get_domain_bus_and_slot() call missing required pci_dev_put()
      PCI: remove depends on CONFIG_EXPERIMENTAL"

* tag '3.8-pci-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: remove depends on CONFIG_EXPERIMENTAL
  PCI: Allow pcie_aspm=force even when FADT indicates it is unsupported
  PCI: shpchp: Use per-slot workqueues to avoid deadlock
  PCI: shpchp: Handle push button event asynchronously
  PCI: shpchp: Make shpchp_wq non-ordered
  PCI/AER: pci_get_domain_bus_and_slot() call missing required pci_dev_put()
  PCI: pciehp: Use per-slot workqueues to avoid deadlock
      1d854908
    • Tejun Heo's avatar
      async: fix __lowest_in_progress() · f56c3196
      Tejun Heo authored 
      Commit 083b804c ("async: use workqueue for worker pool") made it
possible that async jobs are moved from pending to running out-of-order.
While pending async jobs will be queued and dispatched for execution in
the same order, nothing guarantees they'll enter "1) move self to the
running queue" of async_run_entry_fn() in the same order.

Before the conversion, async implemented its own worker pool.  An async
worker, upon being woken up, fetches the first item from the pending
list, which kept the executing lists sorted.  The conversion to
workqueue was done by adding work_struct to each async_entry and async
just schedules the work item.  The queueing and dispatching of such work
items are still in order but now each worker thread is associated with a
specific async_entry and moves that specific async_entry to the
executing list.  So, depending on which worker reaches that point
earlier, which is non-deterministic, we may end up moving an async_entry
with larger cookie before one with smaller one.

This broke __lowest_in_progress().  running->domain may not be properly
sorted and is not guaranteed to contain lower cookies than pending list
when not empty.  Fix it by ensuring sort-inserting to the running list
and always looking at both pending and running when trying to determine
the lowest cookie.

Over time, the async synchronization implementation became quite messy.
We better restructure it such that each async_entry is linked to two
lists - one global and one per domain - and not move it when execution
starts.  There's no reason to distinguish pending and running.  They
behave the same for synchronization purposes.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f56c3196
  13. 22 Jan, 2013 19 commits
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