lkml.org 
[lkml]   [2007]   [Jun]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [BUG] ptraced process waiting on syscall may return kernel internal errnos
    On 06/15, Rafael J. Wysocki wrote:
    >
    > +static void freeze_task(struct task_struct *p)
    > +{
    > if (!freezing(p)) {
    > rmb();
    > if (!frozen(p)) {
    > set_freeze_flag(p);
    > - if (p->state == TASK_STOPPED)
    > - force_sig_specific(SIGSTOP, p);
    > - spin_lock_irqsave(&p->sighand->siglock, flags);
    > - signal_wake_up(p, p->state == TASK_STOPPED);
    > - spin_unlock_irqrestore(&p->sighand->siglock, flags);
    > + task_lock(p);
    > + /* We don't want to send signals to kernel threads */
    > + if (p->mm && !(p->flags & PF_BORROWED_MM)) {
    > + task_unlock(p);
    > + send_fake_signal(p);
    > + } else {
    > + task_unlock(p);
    > + wake_up_state(p, TASK_INTERRUPTIBLE);
    > + }

    I don't think this is enough. Note that recalc_sigpending() checks freezing().
    So a kernel thread still can get TIF_SIGPENDING if it does recalc_sigpending().

    > --- linux-2.6.22-rc4-mm2.orig/include/linux/wait.h 2007-06-15 01:05:33.000000000 +0200
    > +++ linux-2.6.22-rc4-mm2/include/linux/wait.h 2007-06-15 01:05:41.000000000 +0200
    > @@ -240,7 +240,7 @@ do { \
    > prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
    > if (condition) \
    > break; \
    > - if (!signal_pending(current)) { \
    > + if (!signal_pending(current) && !freezing(current)) { \
    > schedule(); \
    > continue; \
    > } \

    Personally, I think we should not modify wait_event_interruptible() and friends.
    If a kernel thread wants to be frozen, it should take care about freezing()
    itself.


    OK, I guess I was too paranoid and you were right, it is better to ignore this
    minor problem for now.

    Oleg.

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-06-15 13:33    [W:0.022 / U:33.148 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site