Messages in this thread | | | Subject | Re: lockdep trace from posix timers | From | Peter Zijlstra <> | Date | Mon, 20 Aug 2012 17:27:16 +0200 |
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On Mon, 2012-08-20 at 17:10 +0200, Peter Zijlstra wrote: > On Mon, 2012-08-20 at 16:59 +0200, Oleg Nesterov wrote: > > On 08/20, Peter Zijlstra wrote: > > > > > > task_work_cancel(struct task_struct *task, task_work_func_t func) > > > { > > > ... > > > + > > > +again: > > > + workp = &task->task_works; > > > + work = *workp; > > > + while (work) { > > > + if (work->func == func) { > > > > But this all can race with task_work_run() if task != current. > > > > This "work" can be freed/reused. And it should only return !NULL > > if twork->func() was not called. > > Ah, because we could be iterating the list after the xchg done by run.
I guess we could steal the entire list and requeue it afterwards and lift TIF_NOTIFY_RESUME along with it.. but I can't say that's pretty.
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