Eric Lee / smarc-fsl-linux-kernel

24 May, 2019

1 commit

  • b4d0d230c   treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 ... Browse Code »

    Based on 1 normalized pattern(s):

    this program is free software you can redistribute it and or modify
    it under the terms of the gnu general public licence as published by
    the free software foundation either version 2 of the licence or at
    your option any later version

    extracted by the scancode license scanner the SPDX license identifier

    GPL-2.0-or-later

    has been chosen to replace the boilerplate/reference in 114 file(s).

    Signed-off-by: Thomas Gleixner
    Reviewed-by: Allison Randal
    Reviewed-by: Kate Stewart
    Cc: linux-spdx@vger.kernel.org
    Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de
    Signed-off-by: Greg Kroah-Hartman

    Thomas Gleixner
     

02 Mar, 2017

3 commits

07 Nov, 2015

1 commit

17 Jul, 2009

3 commits

  • 967cc5371   kernel: is_current_single_threaded: don't use ->mmap_sem ... Browse Code »

    is_current_single_threaded() can safely miss a freshly forked CLONE_VM
    task, but in this case it must not miss its parent. That is why we take
    mm->mmap_sem for writing to make sure a thread/task with the same ->mm
    can't pass exit_mm() and disappear.

    However we can avoid ->mmap_sem and rely on rcu/barriers:

    - if we do not see the exiting parent on thread/process list
    we see the result of list_del_rcu(), in this case we must
    also see the result of list_add_rcu() which does wmb().

    - if we do see the parent but its ->mm == NULL, we need rmb()
    to make sure we can't miss the child.

    Signed-off-by: Oleg Nesterov
    Acked-by: David Howells
    Signed-off-by: James Morris

    Oleg Nesterov
     
  • 5bb459bb4   kernel: rename is_single_threaded(task) to current_is_single_threaded(void) ... Browse Code »

    - is_single_threaded(task) is not safe unless task == current,
    we can't use task->signal or task->mm.

    - it doesn't make sense unless task == current, the task can
    fork right after the check.

    Rename it to current_is_single_threaded() and kill the argument.

    Signed-off-by: Oleg Nesterov
    Acked-by: David Howells
    Signed-off-by: James Morris

    Oleg Nesterov
     
  • d2e3ee9b2   kernel: fix is_single_threaded ... Browse Code »

    - Fix the comment, is_single_threaded(p) actually means that nobody shares
    ->mm with p.

    I think this helper should be renamed, and it should not have arguments.
    With or without this patch it must not be used unless p == current,
    otherwise we can't safely use p->signal or p->mm.

    - "if (atomic_read(&p->signal->count) != 1)" is not right when we have a
    zombie group leader, use signal->live instead.

    - Add PF_KTHREAD check to skip kernel threads which may borrow p->mm,
    otherwise we can return the wrong "false".

    - Use for_each_process() instead of do_each_thread(), all threads must use
    the same ->mm.

    - Use down_write(mm->mmap_sem) + rcu_read_lock() instead of tasklist_lock
    to iterate over the process list. If there is another CLONE_VM process
    it can't pass exit_mm() which takes the same mm->mmap_sem. We can miss
    a freshly forked CLONE_VM task, but this doesn't matter because we must
    see its parent and return false.

    Signed-off-by: Oleg Nesterov
    Cc: David Howells
    Cc: James Morris
    Cc: Roland McGrath
    Cc: Stephen Smalley
    Signed-off-by: Andrew Morton
    Signed-off-by: James Morris

    Oleg Nesterov
     

14 Nov, 2008

1 commit