Hello, Hillf. On Fri, Feb 08, 2013 at 11:39:56AM +0800, Hillf Danton wrote: > The comment just above cpu_stop_signal_done() says it is uncertain that > the input @done is valid, and the works enqueued through the function > stop_one_cpu_nowait() do carry no done, thus we have to check if it is > valid when updating work result.
How about something like the following? In cpu_stopper_thread(), @work->done may be NULL if the cpu stop work is queued from stop_one_cpu_nowait(); however, cpu_stopper_thread() updates @done->ret without checking whether @done exists or not when the work function fails. While this can lead to oops, the only current user of stop_one_cpu_nowait() - active_load_balance_cpu_stop() - always returns 0 and thus there's no in-kernel user which triggers this bug. Fix it by checking whether @done exists before updating @done->ret. > Signed-off-by: Hillf Danton <dhi...@gmail.com> > --- > > --- a/kernel/stop_machine.c Thu Feb 7 20:03:10 2013 > +++ b/kernel/stop_machine.c Fri Feb 8 11:07:40 2013 > @@ -279,7 +279,7 @@ repeat: > preempt_disable(); > > ret = fn(arg); > - if (ret) > + if (ret && done != NULL) It's a nitpick and probalby is just a preference but I've never liked != NULL or != 0. Can we just do if (ret && done)? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
