On Tue 23-10-18 12:30:44, Joel Fernandes wrote: > On Tue, Oct 23, 2018 at 11:13:36AM -0600, Shuah Khan wrote: > > On 10/23/2018 11:05 AM, Michal Hocko wrote: > > > On Tue 23-10-18 08:26:40, Matthew Wilcox wrote: > > >> On Tue, Oct 23, 2018 at 09:02:56AM -0600, Shuah Khan wrote: > > > [...] > > >>> The way it can be handled is by adding a test module under lib. test_kmod, > > >>> test_sysctl, test_user_copy etc. > > >> > > >> The problem is that said module can only invoke functions which are > > >> exported using EXPORT_SYMBOL. And there's a cost to exporting them, > > >> which I don't think we're willing to pay, purely to get test coverage. > > > > > > Yes, I think we do not want to export internal functionality which might > > > be still interesting for the testing coverage. Maybe we want something > > > like EXPORT_SYMBOL_KSELFTEST which would allow to link within the > > > kselftest machinery but it wouldn't allow the same for general modules > > > and will not give any API promisses. > > > > > > > I like this proposal. I think we will open up lot of test opportunities with > > this approach. > > > > Maybe we can use this stress test as a pilot and see where it takes us. > > I am a bit worried that such an EXPORT_SYMBOL_KSELFTEST mechanism can be abused by > out-of-tree module writers to call internal functionality. > > How would you prevent that? There is no way to prevent non-exported symbols abuse by 3rd party AFAIK. EXPORT_SYMBOL_* is not there to prohibid abuse. It is a mere signal of what is, well, an exported API. -- Michal Hocko SUSE Labs
