Eric Lee / smarc-fsl-linux-kernel

24 May, 2015

1 commit

  • a9f6a19b5   power_supply: Use wrappers to avoid races when registering power supply ... Browse Code »

    Use wrappers over get_property() and set_property() internally in power
    supply and for sysfs interface. The wrappers provide safe access if
    power supply is not yet registered or t is being destroyed.

    In case of syfs the theoretical race could happen between ending of
    driver's probe and parallel sysfs access:
    some_driver_probe() userspace
    ==================================== ===========================
    drv->psy = power_supply_register()
    device_add()
    sysfs entries are created
    atomic_inc(&psy->use_cnt);
    store on sysfs attributes
    drv->set_property()
    dereference of drv->psy
    drv->psy = returned psy;

    For leds the race could happen between power supply being destroyed and
    ongoing power_supply_changed_work().

    Signed-off-by: Krzysztof Kozlowski
    Signed-off-by: Sebastian Reichel

    Krzysztof Kozlowski
     

14 Mar, 2015

1 commit

  • 297d716f6   power_supply: Change ownership from driver to core ... Browse Code »

    Change the ownership of power_supply structure from each driver
    implementing the class to the power supply core.

    The patch changes power_supply_register() function thus all drivers
    implementing power supply class are adjusted.

    Each driver provides the implementation of power supply. However it
    should not be the owner of power supply class instance because it is
    exposed by core to other subsystems with power_supply_get_by_name().
    These other subsystems have no knowledge when the driver will unregister
    the power supply. This leads to several issues when driver is unbound -
    mostly because user of power supply accesses freed memory.

    Instead let the core own the instance of struct 'power_supply'. Other
    users of this power supply will still access valid memory because it
    will be freed when device reference count reaches 0. Currently this
    means "it will leak" but power_supply_put() call in next patches will
    solve it.

    This solves invalid memory references in following race condition
    scenario:

    Thread 1: charger manager
    Thread 2: power supply driver, used by charger manager

    THREAD 1 (charger manager) THREAD 2 (power supply driver)
    ========================== ==============================
    psy = power_supply_get_by_name()
    Driver unbind, .remove
    power_supply_unregister()
    Device fully removed
    psy->get_property()

    The 'get_property' call is executed in invalid context because the driver was
    unbound and struct 'power_supply' memory was freed.

    This could be observed easily with charger manager driver (here compiled
    with max17040 fuel gauge):

    $ cat /sys/devices/virtual/power_supply/cm-battery/capacity &
    $ echo "1-0036" > /sys/bus/i2c/drivers/max17040/unbind
    [ 55.725123] Unable to handle kernel NULL pointer dereference at virtual address 00000000
    [ 55.732584] pgd = d98d4000
    [ 55.734060] [00000000] *pgd=5afa2831, *pte=00000000, *ppte=00000000
    [ 55.740318] Internal error: Oops: 80000007 [#1] PREEMPT SMP ARM
    [ 55.746210] Modules linked in:
    [ 55.749259] CPU: 1 PID: 2936 Comm: cat Tainted: G W 3.19.0-rc1-next-20141226-00048-gf79f475f3c44-dirty #1496
    [ 55.760190] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
    [ 55.766270] task: d9b76f00 ti: daf54000 task.ti: daf54000
    [ 55.771647] PC is at 0x0
    [ 55.774182] LR is at charger_get_property+0x2f4/0x36c
    [ 55.779201] pc : [] lr : [] psr: 60000013
    [ 55.779201] sp : daf55e90 ip : 00000003 fp : 00000000
    [ 55.790657] r10: 00000000 r9 : c06e2878 r8 : d9b26c68
    [ 55.795865] r7 : dad81610 r6 : daec7410 r5 : daf55ebc r4 : 00000000
    [ 55.802367] r3 : 00000000 r2 : daf55ebc r1 : 0000002a r0 : d9b26c68
    [ 55.808879] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
    [ 55.815994] Control: 10c5387d Table: 598d406a DAC: 00000015
    [ 55.821723] Process cat (pid: 2936, stack limit = 0xdaf54210)
    [ 55.827451] Stack: (0xdaf55e90 to 0xdaf56000)
    [ 55.831795] 5e80: 60000013 c01459c4 0000002a c06f8ef8
    [ 55.839956] 5ea0: db651000 c06f8ef8 daebac00 c04cb668 daebac08 c0346864 00000000 c01459c4
    [ 55.848115] 5ec0: d99eaa80 c06f8ef8 00000fff 00001000 db651000 c027f25c c027f240 d99eaa80
    [ 55.856274] 5ee0: d9a06c00 c0146218 daf55f18 00001000 d99eaa80 db4c18c0 00000001 00000001
    [ 55.864468] 5f00: daf55f80 c0144c78 c0144c54 c0107f90 00015000 d99eaab0 00000000 00000000
    [ 55.872603] 5f20: 000051c7 00000000 db4c18c0 c04a9370 00015000 00001000 daf55f80 00001000
    [ 55.880763] 5f40: daf54000 00015000 00000000 c00e53dc db4c18c0 c00e548c 0000000d 00008124
    [ 55.888937] 5f60: 00000001 00000000 00000000 db4c18c0 db4c18c0 00001000 00015000 c00e5550
    [ 55.897099] 5f80: 00000000 00000000 00001000 00001000 00015000 00000003 00000003 c000f364
    [ 55.905239] 5fa0: 00000000 c000f1a0 00001000 00015000 00000003 00015000 00001000 0001333c
    [ 55.913399] 5fc0: 00001000 00015000 00000003 00000003 00000002 00000000 00000000 00000000
    [ 55.921560] 5fe0: 7fffe000 be999850 0000a225 b6f3c19c 60000010 00000003 00000000 00000000
    [ 55.929744] [] (charger_get_property) from [] (power_supply_show_property+0x48/0x20c)
    [ 55.939286] [] (power_supply_show_property) from [] (dev_attr_show+0x1c/0x48)
    [ 55.948130] [] (dev_attr_show) from [] (sysfs_kf_seq_show+0x84/0x104)
    [ 55.956298] [] (sysfs_kf_seq_show) from [] (kernfs_seq_show+0x24/0x28)
    [ 55.964536] [] (kernfs_seq_show) from [] (seq_read+0x1b0/0x484)
    [ 55.972172] [] (seq_read) from [] (__vfs_read+0x18/0x4c)
    [ 55.979188] [] (__vfs_read) from [] (vfs_read+0x7c/0x100)
    [ 55.986304] [] (vfs_read) from [] (SyS_read+0x40/0x8c)
    [ 55.993164] [] (SyS_read) from [] (ret_fast_syscall+0x0/0x48)
    [ 56.000626] Code: bad PC value
    [ 56.011652] ---[ end trace 7b64343fbdae8ef1 ]---

    Signed-off-by: Krzysztof Kozlowski
    Reviewed-by: Bartlomiej Zolnierkiewicz

    [for the nvec part]
    Reviewed-by: Marc Dietrich

    [for compal-laptop.c]
    Acked-by: Darren Hart

    [for the mfd part]
    Acked-by: Lee Jones

    [for the hid part]
    Acked-by: Jiri Kosina

    [for the acpi part]
    Acked-by: Rafael J. Wysocki

    Signed-off-by: Sebastian Reichel

    Krzysztof Kozlowski
     

16 Sep, 2014

1 commit

  • 464069cae   power-supply: Avoid unnecessary 'goto' statements ... Browse Code »

    Using 'goto' statements for freeing resources on failures is a good choice as it
    makes code very clean, and reduces the chances of human errors.

    Though in most cases compiler may take care of this. But adding unnecessary
    'goto' statements wouldn't make anything better. Code becomes less readable
    actually.

    Signed-off-by: Viresh Kumar
    Signed-off-by: Sebastian Reichel

    Viresh Kumar
     

12 Mar, 2012

1 commit

  • 51990e825   device.h: cleanup users outside of linux/include (C files) ... Browse Code »

    For files that are actively using linux/device.h, make sure
    that they call it out. This will allow us to clean up some
    of the implicit uses of linux/device.h within include/*
    without introducing build regressions.

    Yes, this was created by "cheating" -- i.e. the headers were
    cleaned up, and then the fallout was found and fixed, and then
    the two commits were reordered. This ensures we don't introduce
    build regressions into the git history.

    Signed-off-by: Paul Gortmaker

    Paul Gortmaker
     

31 Jan, 2011

1 commit

30 Mar, 2010

1 commit

  • 5a0e3ad6a   include cleanup: Update gfp.h and slab.h includes to prepare for breaking implic… ... Browse Code »

    …it slab.h inclusion from percpu.h

    percpu.h is included by sched.h and module.h and thus ends up being
    included when building most .c files. percpu.h includes slab.h which
    in turn includes gfp.h making everything defined by the two files
    universally available and complicating inclusion dependencies.

    percpu.h -> slab.h dependency is about to be removed. Prepare for
    this change by updating users of gfp and slab facilities include those
    headers directly instead of assuming availability. As this conversion
    needs to touch large number of source files, the following script is
    used as the basis of conversion.

    http://userweb.kernel.org/~tj/misc/slabh-sweep.py

    The script does the followings.

    * Scan files for gfp and slab usages and update includes such that
    only the necessary includes are there. ie. if only gfp is used,
    gfp.h, if slab is used, slab.h.

    * When the script inserts a new include, it looks at the include
    blocks and try to put the new include such that its order conforms
    to its surrounding. It's put in the include block which contains
    core kernel includes, in the same order that the rest are ordered -
    alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
    doesn't seem to be any matching order.

    * If the script can't find a place to put a new include (mostly
    because the file doesn't have fitting include block), it prints out
    an error message indicating which .h file needs to be added to the
    file.

    The conversion was done in the following steps.

    1. The initial automatic conversion of all .c files updated slightly
    over 4000 files, deleting around 700 includes and adding ~480 gfp.h
    and ~3000 slab.h inclusions. The script emitted errors for ~400
    files.

    2. Each error was manually checked. Some didn't need the inclusion,
    some needed manual addition while adding it to implementation .h or
    embedding .c file was more appropriate for others. This step added
    inclusions to around 150 files.

    3. The script was run again and the output was compared to the edits
    from #2 to make sure no file was left behind.

    4. Several build tests were done and a couple of problems were fixed.
    e.g. lib/decompress_*.c used malloc/free() wrappers around slab
    APIs requiring slab.h to be added manually.

    5. The script was run on all .h files but without automatically
    editing them as sprinkling gfp.h and slab.h inclusions around .h
    files could easily lead to inclusion dependency hell. Most gfp.h
    inclusion directives were ignored as stuff from gfp.h was usually
    wildly available and often used in preprocessor macros. Each
    slab.h inclusion directive was examined and added manually as
    necessary.

    6. percpu.h was updated not to include slab.h.

    7. Build test were done on the following configurations and failures
    were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
    distributed build env didn't work with gcov compiles) and a few
    more options had to be turned off depending on archs to make things
    build (like ipr on powerpc/64 which failed due to missing writeq).

    * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
    * powerpc and powerpc64 SMP allmodconfig
    * sparc and sparc64 SMP allmodconfig
    * ia64 SMP allmodconfig
    * s390 SMP allmodconfig
    * alpha SMP allmodconfig
    * um on x86_64 SMP allmodconfig

    8. percpu.h modifications were reverted so that it could be applied as
    a separate patch and serve as bisection point.

    Given the fact that I had only a couple of failures from tests on step
    6, I'm fairly confident about the coverage of this conversion patch.
    If there is a breakage, it's likely to be something in one of the arch
    headers which should be easily discoverable easily on most builds of
    the specific arch.

    Signed-off-by: Tejun Heo <tj@kernel.org>
    Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

    Tejun Heo
     

29 Apr, 2008

1 commit

02 Feb, 2008

2 commits

16 Jul, 2007

1 commit

10 Jul, 2007

1 commit

  • 4a11b59d8   [BATTERY] Universal power supply class (was: battery class) ... Browse Code »

    This class is result of "external power" and "battery" classes merge,
    as suggested by David Woodhouse. He also implemented uevent support.

    Here how userspace seeing it now:

    # ls /sys/class/power\ supply/
    ac main-battery usb

    # cat /sys/class/power\ supply/ac/type
    AC

    # cat /sys/class/power\ supply/usb/type
    USB

    # cat /sys/class/power\ supply/main-battery/type
    Battery

    # cat /sys/class/power\ supply/ac/online
    1

    # cat /sys/class/power\ supply/usb/online
    0

    # cat /sys/class/power\ supply/main-battery/status
    Charging

    # cat /sys/class/leds/h5400\:red-left/trigger
    none h5400-radio timer hwtimer ac-online usb-online
    main-battery-charging-or-full [main-battery-charging]
    main-battery-full

    Signed-off-by: Anton Vorontsov
    Signed-off-by: David Woodhouse
    Signed-off-by: Andrew Morton

    Anton Vorontsov