Hi Rafael, If we want the driver core to test driver remove functions, we can enable CONFIG_DEBUG_TEST_DRIVER_REMOVE. This option is just for testing it. So, in most cases, the option is disabled and the if condition is false. So I think we can add an unlikely() to it.
Rafael J. Wysocki <[email protected]> 于2018年11月6日周二 下午10:30写道： > > On Tue, Nov 6, 2018 at 2:47 PM Muchun Song <[email protected]> wrote: > > > > If condition is false in most cases. So, add an unlikely() to the if > > condition, so that the optimizer assumes that the condition is false. > > > > Signed-off-by: Muchun Song <[email protected]> > > Have you measured the practical impact of this patch in any way? > > > --- > > drivers/base/dd.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > > index 169412ee4ae8..8eba453c4e5d 100644 > > --- a/drivers/base/dd.c > > +++ b/drivers/base/dd.c > > @@ -450,7 +450,7 @@ static int really_probe(struct device *dev, struct > > device_driver *drv) > > bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && > > !drv->suppress_bind_attrs; > > > > - if (defer_all_probes) { > > + if (unlikely(defer_all_probes)) { > > /* > > * Value of defer_all_probes can be set only by > > * device_defer_all_probes_enable() which, in turn, will > > call > > @@ -508,7 +508,7 @@ static int really_probe(struct device *dev, struct > > device_driver *drv) > > goto probe_failed; > > } > > > > - if (test_remove) { > > + if (unlikely(test_remove)) { > > test_remove = false; > > > > if (dev->bus->remove) > > -- > > 2.17.1 > >
