On Sun, Feb 10, 2013 at 3:08 AM, Tejun Heo <t...@kernel.org> wrote: > 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?
Cool, I like it, thanks. Hillf > > 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/
