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Howlett" , Suren Baghdasaryan , Vlastimil Babka , pedro.falcato@gmail.com, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Oliver Sang , Shuah Khan References: Content-Language: en-US From: Shuah Khan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/16/24 16:06, Lorenzo Stoakes wrote: > On Wed, Oct 16, 2024 at 02:00:27PM -0600, Shuah Khan wrote: >> On 10/16/24 04:20, Lorenzo Stoakes wrote: >>> Add tests to assert that PIDFD_SELF_* correctly refers to the current >>> thread and process. >>> >>> This is only practically meaningful to pidfd_send_signal() and >>> pidfd_getfd(), but also explicitly test that we disallow this feature for >>> setns() where it would make no sense. >>> >>> We cannot reasonably wait on ourself using waitid(P_PIDFD, ...) so while in >>> theory PIDFD_SELF_* would work here, we'd be left blocked if we tried it. >>> >>> We defer testing of mm-specific functionality which uses pidfd, namely >>> process_madvise() and process_mrelease() to mm testing (though note the >>> latter can not be sensibly tested as it would require the testing process >>> to be dying). >>> >>> Signed-off-by: Lorenzo Stoakes >>> --- >>> tools/testing/selftests/pidfd/pidfd.h | 8 + >>> .../selftests/pidfd/pidfd_getfd_test.c | 141 ++++++++++++++++++ >>> .../selftests/pidfd/pidfd_setns_test.c | 11 ++ >>> tools/testing/selftests/pidfd/pidfd_test.c | 76 ++++++++-- >>> 4 files changed, 224 insertions(+), 12 deletions(-) >>> >>> diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h >>> index 88d6830ee004..1640b711889b 100644 >>> --- a/tools/testing/selftests/pidfd/pidfd.h >>> +++ b/tools/testing/selftests/pidfd/pidfd.h >>> @@ -50,6 +50,14 @@ >>> #define PIDFD_NONBLOCK O_NONBLOCK >>> #endif >>> +/* System header file may not have this available. */ >>> +#ifndef PIDFD_SELF_THREAD >>> +#define PIDFD_SELF_THREAD -100 >>> +#endif >>> +#ifndef PIDFD_SELF_THREAD_GROUP >>> +#define PIDFD_SELF_THREAD_GROUP -200 >>> +#endif >>> + >> >> As mentioned in my response to v1 patch: >> >> kselftest has dependency on "make headers" and tests include >> headers from linux/ directory > > Right but that assumes you install the kernel headers on the build system, > which is quite a painful thing to have to do when you are quickly iterating > on a qemu setup. Yes that is exactly what we do. kselftest build depends on headers install. The way it works for qemu is either using vitme-ng or building tests and installing them in your vm.. This is what CIs do. > > This is a use case I use all the time so not at all theoretical. This is what CIs do. Yes - it works for them to build and install headers. You don't have to install them on the build system. You run "make headers" in your repo. You could use O= option for relocatable build. > > Unfortunately this seems broken on my system anyway :( - see below. > >> >> These local make it difficult to maintain these tests in the >> longer term. Somebody has to go clean these up later. > > I don't agree, tests have to be maintained alongside the core code, and if > these values change (seems unlikely) then the tests will fail and can > easily be updated. > > This was the approach already taken in this file with other linux > header-defined values, so we'll also be breaking the precendence. Some of these defines were added a while back. Often these defines need cleaning up. I would rather not see new ones added unless it is absolutely necessary. > >> >> The import will be fine and you can control that with -I flag in >> the makefile. Remove these and try to get including linux/pidfd.h >> working. > > I just tried this and it's not fine :) it immediately broke the build as > pidfd.h imports linux/fcntl.h which conflicts horribly with system headers > on my machine. > > For instance f_owner_ex gets redefined among others and fails the build e..g: > > /usr/include/asm-generic/fcntl.h:155:8: error: redefinition of ‘struct f_owner_ex’ > 155 | struct f_owner_ex { > | ^~~~~~~~~~ > In file included from /usr/include/bits/fcntl.h:61, > from /usr/include/fcntl.h:35, > from pidfd_test.c:6: > /usr/include/bits/fcntl-linux.h:274:8: note: originally defined here > 274 | struct f_owner_ex > | ^~~~~~~~~~ > > It seems only one other test tries to do this as far as I can tell (I only > did a quick grep), so it's not at all standard it seems. > > This issue occurred even when I used make headers_install to create > sanitised user headers and added them to the include path. > > A quick google suggests linux/fcntl.h (imported by this pidfd.h uapi > header) and system fcntl.h is a known thing. Slightly bizarre... > > I tried removing the include and that resulted in > conflicting: > > In file included from /usr/include/fcntl.h:35, > from /usr/include/sys/mount.h:24, > from pidfd.h:17, > from pidfd_test.c:22: > /usr/include/bits/fcntl.h:35:8: error: redefinition of ‘struct flock’ > 35 | struct flock > | ^~~~~ > In file included from /tmp/hdr/include/asm/fcntl.h:1, > from /tmp/hdr/include/linux/fcntl.h:5, > from /tmp/hdr/include/linux/pidfd.h:7, > from pidfd.h:6: > /usr/include/asm-generic/fcntl.h:195:8: note: originally defined here > 195 | struct flock { > | ^~~~~ > > So I don't think I can actually work around this, at least on my system, > and I can't really sensibly submit a patch that I can't run on my own > machine :) > > I may be missing something here. > >> >> Please revise this patch to include the header file and remove >> these local defines. > > I'm a little stuck because of the above, but I _could_ do the following in > the test pidfd.h header.: > > #define _LINUX_FCNTL_H > #include "../../../../include/uapi/linux/pidfd.h" > #undef _LINUX_FCNTL_H > Does this test really need fcntl.h is another question. This is another problem with too many includes. The test built just fine on my system on 6.12-rc3 with +/* #include */ > Which prevents the problematic linux/fcntl.h header from being included and > includes the right header. > > But I'm not sure this is hugely better than what we already have > maintinability-wise? Either way if something changes to break it it'll > break the test build. > If these defines are in a header file - tests include them. Part of test development is figuring out these problems. > Let me know if this is what you want me to do. Otherwise I'm not sure how > to proceed - this header just seems broken at least on my system (arch > linux at 6.11.1). > > An aside: > > The existing code already taken the approach I take (this is partly why I > did it), I think it'd be out of the scope of my series to change that, for > instance in pidfd.h: > > #ifndef PIDFD_NONBLOCK > #define PIDFD_NONBLOCK O_NONBLOCK > #endif > > Alongside a number of other defines. So those will have to stay at least > for now for being out of scope, but obviously if people would prefer to > move the whole thing that can be followed up later. > >> I would like us to explore before giving up and saying these will stay. thanks, -- Shuah