Eric Lee / smarc-fsl-linux-kernel

21 May, 2019

1 commit

  • 1ccea77e2   treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 ... Browse Code »

    Based on 2 normalized pattern(s):

    this program is free software you can redistribute it and or modify
    it under the terms of the gnu general public license as published by
    the free software foundation either version 2 of the license or at
    your option any later version this program is distributed in the
    hope that it will be useful but without any warranty without even
    the implied warranty of merchantability or fitness for a particular
    purpose see the gnu general public license for more details you
    should have received a copy of the gnu general public license along
    with this program if not see http www gnu org licenses

    this program is free software you can redistribute it and or modify
    it under the terms of the gnu general public license as published by
    the free software foundation either version 2 of the license or at
    your option any later version this program is distributed in the
    hope that it will be useful but without any warranty without even
    the implied warranty of merchantability or fitness for a particular
    purpose see the gnu general public license for more details [based]
    [from] [clk] [highbank] [c] you should have received a copy of the
    gnu general public license along with this program if not see http
    www gnu org licenses

    extracted by the scancode license scanner the SPDX license identifier

    GPL-2.0-or-later

    has been chosen to replace the boilerplate/reference in 355 file(s).

    Signed-off-by: Thomas Gleixner
    Reviewed-by: Kate Stewart
    Reviewed-by: Jilayne Lovejoy
    Reviewed-by: Steve Winslow
    Reviewed-by: Allison Randal
    Cc: linux-spdx@vger.kernel.org
    Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
    Signed-off-by: Greg Kroah-Hartman

    Thomas Gleixner
     

17 Apr, 2018

2 commits

  • 3b2c77d00   livepatch: Allow to call a custom callback when freeing shadow variables ... Browse Code »

    We might need to do some actions before the shadow variable is freed.
    For example, we might need to remove it from a list or free some data
    that it points to.

    This is already possible now. The user can get the shadow variable
    by klp_shadow_get(), do the necessary actions, and then call
    klp_shadow_free().

    This patch allows to do it a more elegant way. The user could implement
    the needed actions in a callback that is passed to klp_shadow_free()
    as a parameter. The callback usually does reverse operations to
    the constructor callback that can be called by klp_shadow_*alloc().

    It is especially useful for klp_shadow_free_all(). There we need to do
    these extra actions for each found shadow variable with the given ID.

    Note that the memory used by the shadow variable itself is still released
    later by rcu callback. It is needed to protect internal structures that
    keep all shadow variables. But the destructor is called immediately.
    The shadow variable must not be access anyway after klp_shadow_free()
    is called. The user is responsible to protect this any suitable way.

    Be aware that the destructor is called under klp_shadow_lock. It is
    the same as for the contructor in klp_shadow_alloc().

    Signed-off-by: Petr Mladek
    Acked-by: Josh Poimboeuf
    Acked-by: Miroslav Benes
    Signed-off-by: Jiri Kosina

    Petr Mladek
     
  • e91c2518a   livepatch: Initialize shadow variables safely by a custom callback ... Browse Code »

    The existing API allows to pass a sample data to initialize the shadow
    data. It works well when the data are position independent. But it fails
    miserably when we need to set a pointer to the shadow structure itself.

    Unfortunately, we might need to initialize the pointer surprisingly
    often because of struct list_head. It is even worse because the list
    might be hidden in other common structures, for example, struct mutex,
    struct wait_queue_head.

    For example, this was needed to fix races in ALSA sequencer. It required
    to add mutex into struct snd_seq_client. See commit b3defb791b26ea06
    ("ALSA: seq: Make ioctls race-free") and commit d15d662e89fc667b9
    ("ALSA: seq: Fix racy pool initializations")

    This patch makes the API more safe. A custom constructor function and data
    are passed to klp_shadow_*alloc() functions instead of the sample data.

    Note that ctor_data are no longer a template for shadow->data. It might
    point to any data that might be necessary when the constructor is called.

    Also note that the constructor is called under klp_shadow_lock. It is
    an internal spin_lock that synchronizes alloc() vs. get() operations,
    see klp_shadow_get_or_alloc(). On one hand, this adds a risk of ABBA
    deadlocks. On the other hand, it allows to do some operations safely.
    For example, we could add the new structure into an existing list.
    This must be done only once when the structure is allocated.

    Reported-by: Nicolai Stange
    Signed-off-by: Petr Mladek
    Acked-by: Josh Poimboeuf
    Acked-by: Miroslav Benes
    Signed-off-by: Jiri Kosina

    Petr Mladek
     

16 Sep, 2017

1 commit

15 Sep, 2017

1 commit

  • 439e7271d   livepatch: introduce shadow variable API ... Browse Code »

    Add exported API for livepatch modules:

    klp_shadow_get()
    klp_shadow_alloc()
    klp_shadow_get_or_alloc()
    klp_shadow_free()
    klp_shadow_free_all()

    that implement "shadow" variables, which allow callers to associate new
    shadow fields to existing data structures. This is intended to be used
    by livepatch modules seeking to emulate additions to data structure
    definitions.

    See Documentation/livepatch/shadow-vars.txt for a summary of the new
    shadow variable API, including a few common use cases.

    See samples/livepatch/livepatch-shadow-* for example modules that
    demonstrate shadow variables.

    [jkosina@suse.cz: fix __klp_shadow_get_or_alloc() comment as spotted by
    Josh]
    Signed-off-by: Joe Lawrence
    Acked-by: Josh Poimboeuf
    Acked-by: Miroslav Benes
    Signed-off-by: Jiri Kosina

    Joe Lawrence