On Tue, 10 Dec 2013 16:46:12 +0100 Borislav Petkov <[email protected]> wrote:
> On Tue, Dec 10, 2013 at 04:42:14PM +0100, Petr Mladek wrote: > > We would like to use text_poke_bp in ftrace. It might be called also during > > boot when there is only one CPU and we do not need to sync the others. > > > > The check is must to have because there are also disabled interrupts during > > the boot. Then the call would cause a deadlock, see the warning in > > "smp_call_function_many", kernel/smp.c:371. > > > > The change is inspired by the code in arch/x86/kernel/ftrace.c. > > > > Signed-off-by: Petr Mladek <[email protected]> > > Reviewed-by: Masami Hiramatsu <[email protected]> > > --- > > arch/x86/kernel/alternative.c | 17 ++++++++++++++--- > > 1 file changed, 14 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c > > index eabed9326d2a..6436beec7b0c 100644 > > --- a/arch/x86/kernel/alternative.c > > +++ b/arch/x86/kernel/alternative.c > > @@ -599,6 +599,17 @@ static void do_sync_core(void *info) > > sync_core(); > > } > > > > +static void run_sync(void) > > Can we call this sync_cores()? > > It is what it does. :) That can be changed in a later patch if needed. It's a static function so the visibility is limited. Not to mention, it was just moved from ftrace.c which calls it run_sync(). We need to keep the same name for the move to not confuse the history of where it came from. -- Steve > > > +{ > > + /* > > + * We do not need to sync other cores during boot when there is only one > > + * CPU enabled. In fact, we must not because there are also disabled > > + * interrupts. The call would fail because of a potential deadlock. > > + */ > > + if (num_online_cpus() != 1) > > + on_each_cpu(do_sync_core, NULL, 1); > > +} > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
