Eric Lee / smarc-fsl-linux-kernel

04 Oct, 2006

1 commit

  • b4dfdbb3c   [PATCH] cpufreq: make the transition_notifier chain use SRCU ... Browse Code »

    This patch (as762) changes the cpufreq_transition_notifier_list from a
    blocking_notifier_head to an srcu_notifier_head. This will prevent errors
    caused attempting to call down_read() to access the notifier chain at a
    time when interrupts must remain disabled, during system suspend.

    It's not clear to me whether this is really necessary; perhaps the chain
    could be made into an atomic_notifier. However a couple of the callout
    routines do use blocking operations, so this approach seems safer.

    The head of the notifier chain needs to be initialized before use; this is
    done by an __init routine at core_initcall time. If this turns out not to
    be a good choice, it can easily be changed.

    Signed-off-by: Alan Stern
    Cc: "Paul E. McKenney"
    Cc: Jesse Brandeburg
    Cc: Dave Jones
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alan Stern
     

27 Sep, 2006

1 commit

12 Aug, 2006

1 commit

01 Aug, 2006

3 commits

  • ea7149702   [CPUFREQ] [2/2] demand load governor modules. ... Browse Code »

    Demand-load cpufreq governor modules if needed.

    Signed-off-by: Jeremy Fitzhardinge
    Signed-off-by: Dave Jones

    Jeremy Fitzhardinge
     
  • 3bcb09a35   [CPUFREQ] [1/2] add __find_governor helper and clean up some error handling. ... Browse Code »

    Adds a __find_governor() helper function to look up a governor by
    name. Also restructures some error handling to conform to the
    "single-exit" model which is generally preferred for kernel code.

    Signed-off-by: Jeremy Fitzhardinge
    Signed-off-by: Dave Jones

    Jeremy Fitzhardinge
     
  • 9c9a43ed2   [CPUFREQ] return error when failing to set minfreq ... Browse Code »

    I just stumbled on this bug/feature, this is how to reproduce it:

    # echo 450000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
    # echo 450000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
    # echo powersave > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
    # cpufreq-info -p
    450000 450000 powersave
    # echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq ; echo $?
    0
    # cpufreq-info -p
    450000 450000 powersave

    Here it is. The kernel refuses to set a min_freq higher than the
    max_freq but it allows a max_freq lower than min_freq (lowering min_freq
    also).

    This behaviour is pretty straightforward (but undocumented) and it
    doesn't return an error altough failing to accomplish the requested
    action (set min_freq).
    The problem (IMO) is basically that userspace is not allowed to set a
    full policy atomically while the kernel always does that thus it must
    enforce an ordering on operations.

    The attached patch returns -EINVAL if trying to increase frequencies
    starting from scaling_min_freq and documents the correct ordering of writes.

    Signed-off-by: Mattia Dongili
    Signed-off-by: Dominik Brodowski
    Signed-off-by: Dave Jones

    --

    Mattia Dongili
     

26 Jul, 2006

1 commit

  • 153d7f3fc   [PATCH] Reorganize the cpufreq cpu hotplug locking to not be totally bizare ... Browse Code »

    The patch below moves the cpu hotplugging higher up in the cpufreq
    layering; this is needed to avoid recursive taking of the cpu hotplug
    lock and to otherwise detangle the mess.

    The new rules are:
    1. you must do lock_cpu_hotplug() around the following functions:
    __cpufreq_driver_target
    __cpufreq_governor (for CPUFREQ_GOV_LIMITS operation only)
    __cpufreq_set_policy
    2. governer methods (.governer) must NOT take the lock_cpu_hotplug()
    lock in any way; they are called with the lock taken already
    3. if your governer spawns a thread that does things, like calling
    __cpufreq_driver_target, your thread must honor rule #1.
    4. the policy lock and other cpufreq internal locks nest within
    the lock_cpu_hotplug() lock.

    I'm not entirely happy about how the __cpufreq_governor rule ended up
    (conditional locking rule depending on the argument) but basically all
    callers pass this as a constant so it's not too horrible.

    The patch also removes the cpufreq_governor() function since during the
    locking audit it turned out to be entirely unused (so no need to fix it)

    The patch works on my testbox, but it could use more testing
    (otoh... it can't be much worse than the current code)

    Signed-off-by: Arjan van de Ven
    Signed-off-by: Linus Torvalds

    Arjan van de Ven
     

08 Jul, 2006

1 commit

  • a496e25df   [PATCH] Fix cpufreq vs hotplug lockdep recursion. ... Browse Code »

    [ There's some not quite baked bits in cpufreq-git right now
    so sending this on as a patch instead ]

    On Thu, 2006-07-06 at 07:58 -0700, Tom London wrote:

    > After installing .2356 I get this each time I boot:
    > =======================================================
    > [ INFO: possible circular locking dependency detected ]
    > -------------------------------------------------------
    > S06cpuspeed/1620 is trying to acquire lock:
    > (dbs_mutex){--..}, at: [] mutex_lock+0x21/0x24
    >
    > but task is already holding lock:
    > (cpucontrol){--..}, at: [] mutex_lock+0x21/0x24
    >
    > which lock already depends on the new lock.
    >

    make sure the cpu hotplug recursive mutex (yuck) is taken early in the
    cpufreq codepaths to avoid a AB-BA deadlock.

    Signed-off-by: Arjan van de Ven
    Signed-off-by: Dave Jones
    Signed-off-by: Linus Torvalds

    Dave Jones
     

01 Jul, 2006

1 commit

28 Jun, 2006

3 commits

  • 74b85f379   [PATCH] cpu hotplug: make cpu_notifier related notifier blocks __cpuinit only ... Browse Code »

    Make notifier_blocks associated with cpu_notifier as __cpuinitdata.

    __cpuinitdata makes sure that the data is init time only unless
    CONFIG_HOTPLUG_CPU is defined.

    Signed-off-by: Chandra Seetharaman
    Cc: Ashok Raj
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Chandra Seetharaman
     
  • 65edc68c3   [PATCH] cpu hotplug: make [un]register_cpu_notifier init time only ... Browse Code »

    CPUs come online only at init time (unless CONFIG_HOTPLUG_CPU is defined).
    So, cpu_notifier functionality need to be available only at init time.

    This patch makes register_cpu_notifier() available only at init time, unless
    CONFIG_HOTPLUG_CPU is defined.

    This patch exports register_cpu_notifier() and unregister_cpu_notifier() only
    if CONFIG_HOTPLUG_CPU is defined.

    Signed-off-by: Chandra Seetharaman
    Cc: Ashok Raj
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Chandra Seetharaman
     
  • 9c7b216d2   [PATCH] cpu hotplug: revert init patch submitted for 2.6.17 ... Browse Code »

    In 2.6.17, there was a problem with cpu_notifiers and XFS. I provided a
    band-aid solution to solve that problem. In the process, i undid all the
    changes you both were making to ensure that these notifiers were available
    only at init time (unless CONFIG_HOTPLUG_CPU is defined).

    We deferred the real fix to 2.6.18. Here is a set of patches that fixes the
    XFS problem cleanly and makes the cpu notifiers available only at init time
    (unless CONFIG_HOTPLUG_CPU is defined).

    If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run
    time.

    This patch reverts the notifier_call changes made in 2.6.17

    Signed-off-by: Chandra Seetharaman
    Cc: Ashok Raj
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Chandra Seetharaman
     

05 Jun, 2006

1 commit

26 Apr, 2006

1 commit

19 Apr, 2006

2 commits

  • 7b14dedd1   [CPUFREQ] drivers/cpufreq/cpufreq.c: static functions mustn't be exported ... Browse Code »

    This patch removes the EXPORT_SYMBOL_GPL of the static function cpufreq_parse_governor().

    Signed-off-by: Adrian Bunk
    Signed-off-by: Dave Jones

    Adrian Bunk
     
  • 7970e08bf   [CPUFREQ] If max_freq got reduced (e.g. by _PPC) a write to sysfs scaling_govern… ... Browse Code »

    …or let cpufreq core stuck at low max_freq for ever

    The previous patch had bugs (locking and refcount).

    This one could also be related to the latest DELL reports.
    But they only slip into this if a user prog (e.g. powersave daemon does when
    AC got (un) plugged due to a scheme change) echos something to
    /sys/../cpufreq/scaling_governor
    while the frequencies got limited by BIOS.

    This one works:

    Subject: Max freq stucks at low freq if reduced by _PPC and sysfs gov access

    The problem is reproducable by(if machine is limiting freqs via BIOS):
    - Unplugging AC -> max freq gets limited
    - echo ${governor} >/sys/.../cpufreq/scaling_governor (policy->user_data.max
    gets overridden with policy->max and will never come up again.)

    This patch exchanged the cpufreq_set_policy call to __cpufreq_set_policy and
    duplicated it's functionality but did not override user_data.max.
    The same happens with overridding min/max values. If freqs are limited and
    you override the min freq value, the max freq global value will also get
    stuck to the limited freq, even if BIOS allows all freqs again.
    Last scenario does only happen if BIOS does not reduce the frequency
    to the lowest value (should never happen, just for correctness...)

    drivers/cpufreq/cpufreq.c | 17 +++++++++++++++--
    1 files changed, 15 insertions(+), 2 deletions(-)

    Signed-off-by: Thomas Renninger <trenn@suse.de>
    Signed-off-by: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>
    Signed-off-by: Dave Jones <davej@redhat.com>

    Thomas Renninger
     

29 Mar, 2006

2 commits

28 Mar, 2006

1 commit

  • e041c6834   [PATCH] Notifier chain update: API changes ... Browse Code »

    The kernel's implementation of notifier chains is unsafe. There is no
    protection against entries being added to or removed from a chain while the
    chain is in use. The issues were discussed in this thread:

    http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2

    We noticed that notifier chains in the kernel fall into two basic usage
    classes:

    "Blocking" chains are always called from a process context
    and the callout routines are allowed to sleep;

    "Atomic" chains can be called from an atomic context and
    the callout routines are not allowed to sleep.

    We decided to codify this distinction and make it part of the API. Therefore
    this set of patches introduces three new, parallel APIs: one for blocking
    notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
    really just the old API under a new name). New kinds of data structures are
    used for the heads of the chains, and new routines are defined for
    registration, unregistration, and calling a chain. The three APIs are
    explained in include/linux/notifier.h and their implementation is in
    kernel/sys.c.

    With atomic and blocking chains, the implementation guarantees that the chain
    links will not be corrupted and that chain callers will not get messed up by
    entries being added or removed. For raw chains the implementation provides no
    guarantees at all; users of this API must provide their own protections. (The
    idea was that situations may come up where the assumptions of the atomic and
    blocking APIs are not appropriate, so it should be possible for users to
    handle these things in their own way.)

    There are some limitations, which should not be too hard to live with. For
    atomic/blocking chains, registration and unregistration must always be done in
    a process context since the chain is protected by a mutex/rwsem. Also, a
    callout routine for a non-raw chain must not try to register or unregister
    entries on its own chain. (This did happen in a couple of places and the code
    had to be changed to avoid it.)

    Since atomic chains may be called from within an NMI handler, they cannot use
    spinlocks for synchronization. Instead we use RCU. The overhead falls almost
    entirely in the unregister routine, which is okay since unregistration is much
    less frequent that calling a chain.

    Here is the list of chains that we adjusted and their classifications. None
    of them use the raw API, so for the moment it is only a placeholder.

    ATOMIC CHAINS
    -------------
    arch/i386/kernel/traps.c: i386die_chain
    arch/ia64/kernel/traps.c: ia64die_chain
    arch/powerpc/kernel/traps.c: powerpc_die_chain
    arch/sparc64/kernel/traps.c: sparc64die_chain
    arch/x86_64/kernel/traps.c: die_chain
    drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list
    kernel/panic.c: panic_notifier_list
    kernel/profile.c: task_free_notifier
    net/bluetooth/hci_core.c: hci_notifier
    net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain
    net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain
    net/ipv6/addrconf.c: inet6addr_chain
    net/netfilter/nf_conntrack_core.c: nf_conntrack_chain
    net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain
    net/netlink/af_netlink.c: netlink_chain

    BLOCKING CHAINS
    ---------------
    arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain
    arch/s390/kernel/process.c: idle_chain
    arch/x86_64/kernel/process.c idle_notifier
    drivers/base/memory.c: memory_chain
    drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list
    drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list
    drivers/macintosh/adb.c: adb_client_list
    drivers/macintosh/via-pmu.c sleep_notifier_list
    drivers/macintosh/via-pmu68k.c sleep_notifier_list
    drivers/macintosh/windfarm_core.c wf_client_list
    drivers/usb/core/notify.c usb_notifier_list
    drivers/video/fbmem.c fb_notifier_list
    kernel/cpu.c cpu_chain
    kernel/module.c module_notify_list
    kernel/profile.c munmap_notifier
    kernel/profile.c task_exit_notifier
    kernel/sys.c reboot_notifier_list
    net/core/dev.c netdev_chain
    net/decnet/dn_dev.c: dnaddr_chain
    net/ipv4/devinet.c: inetaddr_chain

    It's possible that some of these classifications are wrong. If they are,
    please let us know or submit a patch to fix them. Note that any chain that
    gets called very frequently should be atomic, because the rwsem read-locking
    used for blocking chains is very likely to incur cache misses on SMP systems.
    (However, if the chain's callout routines may sleep then the chain cannot be
    atomic.)

    The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
    material written by Keith Owens and suggestions from Paul McKenney and Andrew
    Morton.

    [jes@sgi.com: restructure the notifier chain initialization macros]
    Signed-off-by: Alan Stern
    Signed-off-by: Chandra Seetharaman
    Signed-off-by: Jes Sorensen
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Alan Stern
     

05 Mar, 2006

1 commit

  • 8ff69732d   [CPUFREQ] Fix handling for CPU hotplug ... Browse Code »

    This patch adds proper logic to cpufreq driver in order to handle
    CPU Hotplug.

    When CPUs go on/offline, the affected CPUs data, cpufreq_policy->cpus,
    is not updated properly. This causes sysfs directories and symlinks to
    be in an incorrect state after few CPU on/offlines.

    Signed-off-by: Jacob Shin
    Signed-off-by: Dave Jones

    Dave Jones
     

28 Feb, 2006

1 commit

03 Feb, 2006

2 commits

01 Feb, 2006

1 commit

27 Jan, 2006

1 commit

  • 0961dd0d2   [CPUFREQ] _PPC frequency change issues ... Browse Code »

    BIOS might change frequency behind our back when BIOS changes allowed
    frequencies via _PPC. In this case cpufreq core got out of sync.
    Ask driver for current freq and notify governors about a change

    Signed-off-by: Thomas Renninger
    Signed-off-by: Venkatesh Pallipadi
    Signed-off-by: Dave Jones

    Thomas Renninger
     

19 Jan, 2006

3 commits

15 Jan, 2006

1 commit

07 Dec, 2005

1 commit

  • 95235ca2c   [CPUFREQ] CPU frequency display in /proc/cpuinfo ... Browse Code »

    What is the value shown in "cpu MHz" of /proc/cpuinfo when CPUs are capable of
    changing frequency?

    Today the answer is: It depends.
    On i386:
    SMP kernel - It is always the boot frequency
    UP kernel - Scales with the frequency change and shows that was last set.

    On x86_64:
    There is one single variable cpu_khz that gets written by all the CPUs. So,
    the frequency set by last CPU will be seen on /proc/cpuinfo of all the
    CPUs in the system. What you see also depends on whether you have constant_tsc
    capable CPU or not.

    On ia64:
    It is always boot time frequency of a particular CPU that gets displayed.

    The patch below changes this to:
    Show the last known frequency of the particular CPU, when cpufreq is present. If
    cpu doesnot support changing of frequency through cpufreq, then boot frequency
    will be shown. The patch affects i386, x86_64 and ia64 architectures.

    Signed-off-by: Venkatesh Pallipadi
    Signed-off-by: Dave Jones

    Venkatesh Pallipadi
     

29 Nov, 2005

1 commit

  • a9d9baa1e   [PATCH] clean up lock_cpu_hotplug() in cpufreq ... Browse Code »

    There are some callers in cpufreq hotplug notify path that the lowest
    function calls lock_cpu_hotplug(). The lock is already held during
    cpu_up() and cpu_down() calls when the notify calls are broadcast to
    registered clients.

    Ideally if possible, we could disable_preempt() at the highest caller and
    make sure we dont sleep in the path down in cpufreq->driver_target() calls
    but the calls are so intertwined and cumbersome to cleanup.

    Hence we consistently use lock_cpu_hotplug() and unlock_cpu_hotplug() in
    all places.

    - Removed export of cpucontrol semaphore and made it static.
    - removed explicit uses of up/down with lock_cpu_hotplug()
    so we can keep track of the the callers in same thread context and
    just keep refcounts without calling a down() that causes a deadlock.
    - Removed current_in_hotplug() uses
    - Removed PF_HOTPLUG_CPU in sched.h introduced for the current_in_hotplug()
    temporary workaround.

    Tested with insmod of cpufreq_stat.ko, and logical online/offline
    to make sure we dont have any hang situations.

    Signed-off-by: Ashok Raj
    Cc: Zwane Mwaikambo
    Cc: Shaohua Li
    Cc: "Siddha, Suresh B"
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ashok Raj
     

23 Nov, 2005

1 commit

09 Nov, 2005

1 commit

  • 90d45d17f   [PATCH] cpu hotplug: fix locking in cpufreq drivers ... Browse Code »

    When calling target drivers to set frequency, we take cpucontrol lock.
    When we modified the code to accomodate CPU hotplug, there was an attempt
    to take a double lock of cpucontrol leading to a deadlock. Since the
    current thread context is already holding the cpucontrol lock, we dont need
    to make another attempt to acquire it.

    Now we leave a trace in current->flags indicating current thread already is
    under cpucontrol lock held, so we dont attempt to do this another time.

    Thanks to Andrew Morton for the beating:-)

    From: Brice Goglin

    Build fix

    (akpm: this patch is still unpleasant. Ashok continues to look for a cleaner
    solution, doesn't he? ;))

    Signed-off-by: Ashok Raj
    Signed-off-by: Brice Goglin
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ashok Raj
     

08 Nov, 2005

1 commit

31 Oct, 2005

2 commits

  • c32b6b8e5   [PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers ... Browse Code »

    cpufreq entries in sysfs should only be populated when CPU is online state.
    When we either boot with maxcpus=x and then boot the other cpus by echoing
    to sysfs online file, these entries should be created and destroyed when
    CPU_DEAD is notified. Same treatement as cache entries under sysfs.

    We place the processor in the lowest frequency, so hw managed P-State
    transitions can still work on the other threads to save power.

    Primary goal was to just make these directories appear/disapper dynamically.

    There is one in this patch i had to do, which i really dont like myself but
    probably best if someone handling the cpufreq infrastructure could give
    this code right treatment if this is not acceptable. I guess its probably
    good for the first cut.

    - Converting lock_cpu_hotplug()/unlock_cpu_hotplug() to disable/enable preempt.
    The locking was smack in the middle of the notification path, when the
    hotplug is already holding the lock. I tried another solution to avoid this
    so avoid taking locks if we know we are from notification path. The solution
    was getting very ugly and i decided this was probably good for this iteration
    until someone who understands cpufreq could do a better job than me.

    (akpm: export cpucontrol to GPL modules: drivers/cpufreq/cpufreq_stats.c now
    does lock_cpu_hotplug())

    Signed-off-by: Ashok Raj
    Signed-off-by: Venkatesh Pallipadi
    Cc: Dave Jones
    Cc: Zwane Mwaikambo
    Cc: Greg KH
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ashok Raj
     
  • d434fca73   [PATCH] Remove cpu_sys_devices in cpufreq subsystem. ... Browse Code »

    cpu_sys_devices is redundant with the new API get_cpu_sysdev(). So nuking
    this usage since its not needed.

    Signed-off-by: Ashok Raj
    Signed-off-by: Venkatesh Pallipadi
    Cc: Dave Jones
    Cc: Zwane Mwaikambo
    Cc: Greg KH
    Signed-off-by: Andrew Morton
    Signed-off-by: Linus Torvalds

    Ashok Raj
     

21 Oct, 2005

1 commit

01 Sep, 2005

1 commit

29 Jul, 2005

1 commit

08 Jul, 2005

1 commit