On Mon 2019-05-13 12:13:20, Andy Shevchenko wrote:
On Mon, May 13, 2019 at 08:52:41AM +0000, David Laight wrote:
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From: christophe leroy
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Sent: 10 May 2019 18:35
Le 10/05/2019 à 18:24, Steven Rostedt a écrit :
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On Fri, 10 May 2019 10:42:13 +0200
Petr Mladek [off-list ref] wrote:
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- if (probe_kernel_address(ptr, byte))
+ if ((unsigned long)ptr < PAGE_SIZE || IS_ERR_VALUE(ptr))
return "(efault)";
"efault" looks a bit like a spellling mistake for "default".
It's a special, thus it's in parenthesis, though somebody can be
misguided.
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Usually, < PAGE_SIZE means NULL pointer dereference (via the member of a
struct)
Maybe the caller should pass in a short buffer so that you can return
"(err-%d)"
or "(null+%#x)" ?
There are many vsprintf() users. I am afraid that nobody would want
to define extra buffers for error messages. It must fit into
the one for the formatted string.
In both cases it should be limited to the size of pointer (8 or 16
characters). Something like "(e:%4d)" would work for error codes.
I am afraid that we could get 10 different proposals from a huge
enough group of people. I wanted to start with something simple
(source code). I know that (efault) might be confused with
"default" but it is still just one string to grep.
The "(null)" is good enough by itself and already an established
practice..
(efault) made more sense with the probe_kernel_read() that
checked wide range of addresses. Well, I still think that
it makes sense to distinguish a pure NULL. And it still
used also for IS_ERR_VALUE().
Best Regards,
Petr