lkml.org 
[lkml]   [2009]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[tip:sched/urgent] sched: Make wakeup side and atomic variants of completion API irq safe
    Commit-ID:  7539a3b3d1f892dd97eaf094134d7de55c13befe
    Gitweb: http://git.kernel.org/tip/7539a3b3d1f892dd97eaf094134d7de55c13befe
    Author: Rafael J. Wysocki <rjw@sisk.pl>
    AuthorDate: Sun, 13 Dec 2009 00:07:30 +0100
    Committer: Ingo Molnar <mingo@elte.hu>
    CommitDate: Sun, 13 Dec 2009 08:12:46 +0100

    sched: Make wakeup side and atomic variants of completion API irq safe

    Alan Stern noticed that all the wakeup side (and atomic) variants of the
    completion APIs should be irq safe, but the newly introduced
    completion_done() and try_wait_for_completion() aren't. The use of the
    irq unsafe variants in IRQ contexts can cause crashes/hangs.

    Fix the problem by making them use spin_lock_irqsave() and
    spin_lock_irqrestore().

    Reported-by: Alan Stern <stern@rowland.harvard.edu>
    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Zhang Rui <rui.zhang@intel.com>
    Cc: pm list <linux-pm@lists.linux-foundation.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: David Chinner <david@fromorbit.com>
    Cc: Lachlan McIlroy <lachlan@sgi.com>
    LKML-Reference: <200912130007.30541.rjw@sisk.pl>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    ---
    kernel/sched.c | 10 ++++++----
    1 files changed, 6 insertions(+), 4 deletions(-)

    diff --git a/kernel/sched.c b/kernel/sched.c
    index ff39cad..8b3532f 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -5908,14 +5908,15 @@ EXPORT_SYMBOL(wait_for_completion_killable);
    */
    bool try_wait_for_completion(struct completion *x)
    {
    + unsigned long flags;
    int ret = 1;

    - spin_lock_irq(&x->wait.lock);
    + spin_lock_irqsave(&x->wait.lock, flags);
    if (!x->done)
    ret = 0;
    else
    x->done--;
    - spin_unlock_irq(&x->wait.lock);
    + spin_unlock_irqrestore(&x->wait.lock, flags);
    return ret;
    }
    EXPORT_SYMBOL(try_wait_for_completion);
    @@ -5930,12 +5931,13 @@ EXPORT_SYMBOL(try_wait_for_completion);
    */
    bool completion_done(struct completion *x)
    {
    + unsigned long flags;
    int ret = 1;

    - spin_lock_irq(&x->wait.lock);
    + spin_lock_irqsave(&x->wait.lock, flags);
    if (!x->done)
    ret = 0;
    - spin_unlock_irq(&x->wait.lock);
    + spin_unlock_irqrestore(&x->wait.lock, flags);
    return ret;
    }
    EXPORT_SYMBOL(completion_done);

    \
     
     \ /
      Last update: 2009-12-13 08:41    [W:5.579 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site