From: Brendan Higgins <email@example.com> To: David Gow <firstname.lastname@example.org> Cc: Dan Carpenter <email@example.com>, Shuah Khan <firstname.lastname@example.org>, Andrew Morton <email@example.com>, Kees Cook <firstname.lastname@example.org>, "open list:KERNEL SELFTEST FRAMEWORK" <email@example.com>, KUnit Development <firstname.lastname@example.org>, Linux Kernel Mailing List <email@example.com> Subject: Re: [PATCH linux-kselftest/test v4] lib/list-test: add a test for the 'list' doubly linked list Date: Wed, 23 Oct 2019 14:25:49 -0700 [thread overview] Message-ID: <CAFd5g46BuY02M_QBD3PVFnbsvO7fuuS+ZOBmfFBmmGy3xSMXbQ@mail.gmail.com> (raw) In-Reply-To: <CABVgOSkegmhmeRa=7Qcx3MnX88wLy9qZx97CMhk4NvWb-pgpYQ@mail.gmail.com> On Tue, Oct 22, 2019 at 3:13 PM David Gow <firstname.lastname@example.org> wrote: > > On Sat, Oct 19, 2019 at 1:27 AM Dan Carpenter <email@example.com> wrote: > > > > On Fri, Oct 18, 2019 at 02:55:49PM -0700, David Gow wrote: > > > + list4 = kzalloc(sizeof(*list4), GFP_KERNEL); > > > + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, list4); > > > > Why not just use GFP_KERNEL | GFP_NOFAIL and remove the check? > > I've sent a new version of the patch out (v5) which uses __GFP_NOFAIL instead. > > The idea had been to exercise KUnit's assertion functionality, in the > hope that it'd allow the test to fail (but potentially allow other > tests to still run) in the case of allocation failure. Given that > we're only allocating enough to store ~4 pointers in total, though, > that's probably of little use. > > > kzalloc() can't return error pointers. If this were an IS_ERR_OR_NULL() > > check then it would generate a static checker warning, but static > > checkers don't know about KUNIT_ASSERT_NOT_ERR_OR_NULL() yet so you're > > safe. > > Alas, KUnit doesn't have a KUNIT_ASSERT_NOT_NULL() macro, and I'd > assumed it was not dangerous (even if not ideal) to check for error > pointers, even if kzalloc() can't return them. Maybe it would be good for us (not in this case, just generally speaking) to add a KUNIT_ASSERT_NOT_NULL() and friends? > Perhaps it'd make sense to add a convenient way of checking the > NULL-ness of pointers to KUnit (it's possible with the > KUNIT_ASSERT_PTR_EQ(), but requires a bit of casting to make the type > checker happy) in the future. Once KUnit is properly upstream, it may > be worth teaching the static analysis tools about these functions to > avoid having warnings in these sorts of tests. > > For now, though, (and for this test in particular), I agree with the > suggestion of just using __GFP_NOFAIL. > > Thanks a lot for the comments, > -- David
prev parent reply other threads:[~2019-10-23 21:26 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-10-18 21:55 David Gow 2019-10-19 8:27 ` Dan Carpenter 2019-10-22 22:13 ` David Gow 2019-10-23 21:25 ` Brendan Higgins [this message]
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