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Date:   Tue, 14 May 2019 15:35:03 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     David Laight <David.Laight@aculab.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
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        Linus Torvalds <torvalds@linux-foundation.org>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
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        Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH] vsprintf: Do not break early boot with probing
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On Tue, 14 May 2019 21:13:06 +0200
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> > > Do we care about the value? "(-E%u)"?  
> >
> > That too could be confusing. What would (-E22) be considered by a user
> > doing an sprintf() on some string. I know that would confuse me, or I
> > would think that it was what the %pX displayed, and wonder why it
> > displayed it that way. Whereas "(fault)" is quite obvious for any %p
> > use case.  
> 
> I would immediately understand there's a missing IS_ERR() check in a
> function that can return  -EINVAL, without having to add a new printk()
> to find out what kind of bogus value has been received, and without
> having to reboot, and trying to reproduce...

Hi Geert,

I have to ask. Has there actually been a case that you used a %pX and
it faulted, and you had to go back to find what the value of the
failure was?

IMO, sprintf() should not be a tool to do this, because then people
will not add their IS_ERR() and just let sprintf() do the job for them.
I don't think that would be wise to allow.

-- Steve