From: Valdis.Kletnieks@vt.edu
Subject: Re: [PATCH 2/9] ext4: Use pr_fmt and pr_<level>
Date: Tue, 20 Mar 2012 01:46:06 -0400
Message-ID: <216818.1332222366@turing-police.cc.vt.edu>
References: <20120319153133.GA2502@thunk.org> <CAJL_dMtC9fnOsY=4uDVJD=-h5u-qW=xjaf64gtDcgnKX2brhPw@mail.gmail.com> <20120319161425.GB2502@thunk.org> <20120319.141402.934377752041508724.davem@davemloft.net> <20120319183126.GA6031@thunk.org> <1332182773.3908.11.camel@joe2Laptop> <20120320010401.GA14363@thunk.org> <1332207202.7847.23.camel@joe2Laptop> <20120320014707.GD14363@thunk.org> <1332208741.7847.46.camel@joe2Laptop> <20120320025835.GE14363@thunk.org>
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Cc: "Ted Ts'o" <tytso@mit.edu>, David Miller <davem@davemloft.net>,
	anca.emanuel@gmail.com, adilger.kernel@dilger.ca,
	linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org
To: Joe Perches <joe@perches.com>
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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]
>
> > 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.


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