Re: [PATCH 2/9] ext4: Use pr_fmt and pr_<level>

On Mon, 19 Mar 2012 20:02:54 PDT, Joe Perches said:

On Mon, 2012-03-19 at 22:58 -0400, Ted Ts'o wrote:

[good stuff]

quoted

Of course, the body of the message needs to be standardized too.  But
that's orthogonal to the problem of passing the kernel structure which
identifies the object which the log message is about.  That part is
completely and utterly necessary if you're going to standardize the
*first* part of the printable dmesg log, which contains the structured
information.

All of what you say is true, but you're neglecting
the ability to scrape or notify a particular set of
per subsystem messages that pr_<level> could easily
provide that a bare printk could not.

OK. Say I'm a scraper.  How do I distinguish between:

pr_info("foo");
printk(KERN_INFO "foo");

Oh my. seems that both result in exactly the same thing ending up in the
dmesg buffer, so a scraper can't tell the difference because there isn't any...

pr_<level> isn't currently providing any ability to scrap or notify that can't
be done equally well by a printk.  Now if you fix things so there's actual
advantage to or_<level>, then I'm sure Ted will be willing to listen.