linux-kernel - Re: [PATCH 4/4] test_printf: test printf family at runtime

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Date:	Wed, 30 Sep 2015 09:38:06 +0300
From:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:	Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 4/4] test_printf: test printf family at runtime

On Mon, 2015-09-28 at 22:55 +0200, Rasmus Villemoes wrote:
> On Mon, Sep 28 2015, Andy Shevchenko <
> andriy.shevchenko@...ux.intel.com> wrote:
> 
> > On Fri, 2015-09-25 at 19:41 +0200, Rasmus Villemoes wrote:
> > > This adds a simple module for testing the kernel's printf
> > > facilities. Previously, some %p extensions have caused a wrong 
> > > return
> > > value in case the entire output didn't fit and/or been unusable 
> > > in
> > > kasprintf(). This should help catch such issues. Also, it should 
> > > help
> > > ensure that changes to the formatting algorithms don't break 
> > > anything.
> > > 
> > > I'm not sure if we have a struct dentry or struct file lying 
> > > around 
> > > at
> > > boot time or if we can fake one, but most %p extensions should be
> > > testable, as should the ordinary number and string formatting.
> > > 
> > > The nature of vararg functions means we can't use a more 
> > > conventional
> > > table-driven approach.
> > > 
> > > For now, this is mostly a skeleton; contributions are very
> > > welcome. Some tests are/will be slightly annoying to write, since 
> > > the
> > > expected output depends on stuff like CONFIG_*, sizeof(long), 
> > > runtime
> > > values etc.
> > 
> > Few comments below.


> > > +#define test(expect, fmt, ...)				
> > > \
> > > +	__test(expect, strlen(expect), fmt, ##__VA_ARGS__)
> > 
> > Would be __test_m[em] / __test_s[tr] to distinguish them by name?
> 
> Erh, no. The 'mem' version will only be used in a very few cases, and 
> I
> really want the simple name "test" for the common case.

> > > +static void __init
> > > +test_basic(void)
> > > +{
> > > +	test("", "");
> > > +	test("100%", "100%%");
> > > +	test("xxx%yyy", "xxx%cyyy", '%');
> > > +	__test("xxx\0yyy", 7, "xxx%cyyy", '\0');
> > 
> > And such pieces will be look better
> > 
> > __test_str("xxx%yyy", "xxx%cyyy", '%');
> > __test_mem("xxx\0yyy", 7, "xxx%cyyy", '\0');
> 
> I don't agree. 

It's still better to distinguish what function does by names
test vs. __test confuses me.

But whatever, this is a test suite, not an actual code anyway.

> >Maybe commentary delimiter here and above where you have double
> >empty
> >line.
> 
> And say what? I can avoid double empty lines if they bother you.

So, what was the reason to add them in the first place?

> > > +
> > > +MODULE_AUTHOR("Rasmus Villemoes <linux@...musvillemoes.dk>");
> > > +MODULE_LICENSE("GPL");
> > 
> > GPL or ?..
> 
> Honestly, I don't really care. Would you like BSD/GPL or what? I just
> copied from the majority of MODULE_LICENSE() instances.

You are the author, your choice. I'm okay with any applicable type.

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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