Eric Lee / smarc-ti-linux-kernel

15 Jan, 2014

1 commit

  • 2995fa78e   dm sysfs: fix a module unload race ... Browse Code »

    This reverts commit be35f48610 ("dm: wait until embedded kobject is
    released before destroying a device") and provides an improved fix.

    The kobject release code that calls the completion must be placed in a
    non-module file, otherwise there is a module unload race (if the process
    calling dm_kobject_release is preempted and the DM module unloaded after
    the completion is triggered, but before dm_kobject_release returns).

    To fix this race, this patch moves the completion code to dm-builtin.c
    which is always compiled directly into the kernel if BLK_DEV_DM is
    selected.

    The patch introduces a new dm_kobject_holder structure, its purpose is
    to keep the completion and kobject in one place, so that it can be
    accessed from non-module code without the need to export the layout of
    struct mapped_device to that code.

    Signed-off-by: Mikulas Patocka
    Signed-off-by: Mike Snitzer
    Cc: stable@vger.kernel.org

    Mikulas Patocka
     

08 Jan, 2014

1 commit

  • be35f4861   dm: wait until embedded kobject is released before destroying a device ... Browse Code »

    There may be other parts of the kernel holding a reference on the dm
    kobject. We must wait until all references are dropped before
    deallocating the mapped_device structure.

    The dm_kobject_release method signals that all references are dropped
    via completion. But dm_kobject_release doesn't free the kobject (which
    is embedded in the mapped_device structure).

    This is the sequence of operations:
    * when destroying a DM device, call kobject_put from dm_sysfs_exit
    * wait until all users stop using the kobject, when it happens the
    release method is called
    * the release method signals the completion and should return without
    delay
    * the dm device removal code that waits on the completion continues
    * the dm device removal code drops the dm_mod reference the device had
    * the dm device removal code frees the mapped_device structure that
    contains the kobject

    Using kobject this way should avoid the module unload race that was
    mentioned at the beginning of this thread:
    https://lkml.org/lkml/2014/1/4/83

    Signed-off-by: Mikulas Patocka
    Signed-off-by: Mike Snitzer
    Cc: stable@vger.kernel.org

    Mikulas Patocka
     

08 Mar, 2010

1 commit

  • 52cf25d0a   Driver core: Constify struct sysfs_ops in struct kobj_type ... Browse Code »

    Constify struct sysfs_ops.

    This is part of the ops structure constification
    effort started by Arjan van de Ven et al.

    Benefits of this constification:

    * prevents modification of data that is shared
    (referenced) by many other structure instances
    at runtime

    * detects/prevents accidental (but not intentional)
    modification attempts on archs that enforce
    read-only kernel data at runtime

    * potentially better optimized code as the compiler
    can assume that the const data cannot be changed

    * the compiler/linker move const data into .rodata
    and therefore exclude them from false sharing

    Signed-off-by: Emese Revfy
    Acked-by: David Teigland
    Acked-by: Matt Domsch
    Acked-by: Maciej Sosnowski
    Acked-by: Hans J. Koch
    Acked-by: Pekka Enberg
    Acked-by: Jens Axboe
    Acked-by: Stephen Hemminger
    Signed-off-by: Greg Kroah-Hartman

    Emese Revfy
     

17 Feb, 2010

1 commit

  • 9307f6b19   dm: sysfs revert add empty release function to avoid debug warning ... Browse Code »

    Revert commit d2bb7df8cac647b92f51fb84ae735771e7adbfa7 at Greg's request.

    Author: Milan Broz
    Date: Thu Dec 10 23:51:53 2009 +0000

    dm: sysfs add empty release function to avoid debug warning

    This patch just removes an unnecessary warning:
    kobject: 'dm': does not have a release() function,
    it is broken and must be fixed.

    The kobject is embedded in mapped device struct, so
    code does not need to release memory explicitly here.

    Cc: Greg KH
    Signed-off-by: Alasdair G Kergon

    Alasdair G Kergon
     

11 Dec, 2009

2 commits

22 Jun, 2009

1 commit