Messages in this thread | | | Date | Wed, 20 Apr 2022 15:17:31 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/5] sched,ptrace: Fix ptrace_check_attach() vs PREEMPT_RT |
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On Mon, Apr 18, 2022 at 07:01:05PM +0200, Oleg Nesterov wrote:
> diff --git a/include/linux/sched/jobctl.h b/include/linux/sched/jobctl.h > index ec8b312f7506..1b5a57048e13 100644 > --- a/include/linux/sched/jobctl.h > +++ b/include/linux/sched/jobctl.h > @@ -22,7 +22,8 @@ struct task_struct; > > #define JOBCTL_STOPPED_BIT 24 > #define JOBCTL_TRACED_BIT 25 > +#define JOBCTL_TRACED_XXX_BIT 25
26, also we must come up with a better name than tripple-x. In my head it's started to be called TRACED_OLEG, but that can't be right either ;-)
Does something like:
#define JOBCTL_TRACED_BIT 25 #define JOBCTL_TRACED_QUIESCE_BIT 26
work?
> diff --git a/kernel/signal.c b/kernel/signal.c > index 0aea3f0a8002..c7a89904cc4a 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -2182,6 +2182,13 @@ static void do_notify_parent_cldstop(struct task_struct *tsk, > spin_unlock_irqrestore(&sighand->siglock, flags); > } > > +static void clear_traced_xxx(void) > +{ > + spin_lock_irq(¤t->sighand->siglock); > + current->jobctl &= ~JOBCTL_TRACED_XXX; > + spin_unlock_irq(¤t->sighand->siglock); > +} > + > /* > * This must be called with current->sighand->siglock held. > * > @@ -2220,7 +2227,7 @@ static int ptrace_stop(int exit_code, int why, int clear_code, > * schedule() will not sleep if there is a pending signal that > * can awaken the task. > */ > - current->jobctl |= JOBCTL_TRACED; > + current->jobctl |= JOBCTL_TRACED | JOBCTL_TRACED_XXX; > set_special_state(TASK_TRACED); > > /* > @@ -2282,6 +2289,8 @@ static int ptrace_stop(int exit_code, int why, int clear_code, > if (gstop_done && ptrace_reparented(current)) > do_notify_parent_cldstop(current, false, why); > > + clear_traced_xxx(); > + wake_up_state(current->parent, TASK_KILLABLE); > /* > * Don't want to allow preemption here, because > * sys_ptrace() needs this task to be inactive. > @@ -2297,8 +2306,12 @@ static int ptrace_stop(int exit_code, int why, int clear_code, > } else { > /* > * By the time we got the lock, our tracer went away. > - * Don't drop the lock yet, another tracer may come. > - * > + * Don't drop the lock yet, another tracer may come, > + * tasklist protects us from ptrace_freeze_traced(). > + */ > + __set_current_state(TASK_RUNNING); > + clear_traced_xxx(); > + /* > * If @gstop_done, the ptracer went away between group stop > * completion and here. During detach, it would have set > * JOBCTL_STOP_PENDING on us and we'll re-enter
This is that same else clause again; perhaps make signal_wake_up_state() also clear TRACED_XXX instead?
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