On Mon 2019-05-13 12:13:20, Andy Shevchenko wrote: > On Mon, May 13, 2019 at 08:52:41AM +0000, David Laight wrote: > > From: christophe leroy > > > Sent: 10 May 2019 18:35 > > > Le 10/05/2019 à 18:24, Steven Rostedt a écrit : > > > > On Fri, 10 May 2019 10:42:13 +0200 > > > > Petr Mladek <pmladek@xxxxxxxx> wrote: > > > > >> - 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. > > > > 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
