On Sat 2020-02-22 00:52:27, Rasmus Villemoes wrote:

On 21/02/2020 14.05, Petr Mladek wrote:

quoted

On Thu 2020-02-20 16:02:48, Ilya Dryomov wrote:

quoted

quoted

I would like to see it in 5.6, so that it is backported to 5.4 and 5.5.

Sorry to be that guy, but yes, I'm against changing the behavior of
vsnprintf() without at least some test(s) added to the test suite - the
lack of machine-checked documentation in the form of tests is what led
to that regression in the first place.

I would not call this regression. It was intentional. The change in
5.2 unified the behavior for the other %p? modifiers. I simply did
not care about plain %p because it was already crippled by the hashing.

I am fine with the proposed change. But the more I think about it
the less I want to rush it in for 5.6. The proposed patch changes
the behavior again:

Value           Output v5.1       Output v5.2      Proposal

NULL                       (null) 00000000<.hash.> 0000000000000000
fffffffffffffffe 00000000<.hash.> 00000000<.hash.> fffffffffffffffe
ffffffff12345678 00000000<.hash.> 00000000<.hash.> 00000000<.hash.>

I do not want to change this in rc phase. I would really like to wait
for 5.7.

But I agree that there's no point adding another helper function and
muddying the test suite even more (especially as the name error_pointer
is too close to the name errptr() I chose a few months back for the %pe).

So how about

- remove the now stale test_hashed("%p", NULL); from null_pointer()
- add tests of "%p", NULL and "%p", ERR_PTR(-123) to plain()

and we save testing the "%px" case for when we figure out a good name
for a helper for that (explicit_pointer? pointer_as_hex?)

In this, case I would prefer to fix the tests properly first. There
have been only few commits in lib/test_printf.c since 5.2. And they
should not conflict with the changes proposed at
https://lkml.kernel.org/r/20200220125707.hbcox3xgevpezq4l@pathway.suse.cz
So it should be easy to backport as well.

If you want, I could sent the cleanup patch properly for review.

Best Regards,
Petr