On Fri, Feb 15, 2008 at 10:52:51AM -0500, Alan Stern wrote: > On Fri, 15 Feb 2008, Yi Yang wrote: > > > This patch adds kobject_put to balance refcount. I noticed Greg suggests > > it will fix a power-off issue to remove kobject_get statement block, but i > > think that isn't the best way because those code block has existed very long > > and it is helpful because the successive statements are invoking relevant > > data. > > Are you referring to this section of code (before the region affected > by your patch)? > > if (!kobject_get(&data->kobj)) { > spin_unlock_irqrestore(&cpufreq_driver_lock, flags); > cpufreq_debug_enable_ratelimit(); > unlock_policy_rwsem_write(cpu); > return -EFAULT; > } > > Greg is correct that the kobject_get() here is useless and should be > removed. kobject_get() never returns NULL unless its argument is NULL. > Since &data->kobj can never be NULL, the "if" test will never fail. > Hence there's no point in making the test at all. > > The fact that a section of code has existed for a long time doesn't > mean that it is right. :-) > > Furthermore, there's no reason to do the kobject_get(). Holding 2 > references to a kobject is no better than holding just 1 reference. > Assuming you know that the kobject is still registered, then you also > know that there is already a reference to it. So you have no reason to > take an additional reference. There's the additional problem that this second reference count is never dropped, causing a bug :) thanks, greg k-h _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm