linux-kernel - Re: + remove-current-defines-and-uses-of-pr_err-add-pr

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Date:	Wed, 08 Aug 2007 15:21:53 -0700
From:	Joe Perches <joe@...ches.com>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
Cc:	Jean Delvare <khali@...ux-fr.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, mm-commits@...r.kernel.org,
	adaplas@....net, greg@...ah.com, jeff@...zik.org
Subject: Re: + remove-current-defines-and-uses-of-pr_err-add-pr_emerg.patch
	added to -mm tree

On Wed, 2007-08-08 at 23:57 +0200, Jan Engelhardt wrote:
> fs/freevxfs/vxfs_bmap.c:line 169 (near "case VXFS_TYPED_DATA_DEV4")
> 
>                         printk(KERN_INFO "\n\nTYPED_DEV4 detected!\n");
> Seems normal.

The second output log line of the first printk isn't prefixed
with KERN_INFO.  It's output with log_level_unknown.

> So it looks like your regex has some false positives.
> (which nothing can be done about - the 61 must be hand-sorted)

Must have copy/pasted the wrong regex

$ egrep -r "printk[[:space:]]*\([[:space:]]*KERN.*\\\n[A-JL-Za-jl-z[:space:]]" --include=*.[ch] * | wc -l
61

> [My idea is above]

Any sequence of printks can be interleaved.  I don't see
how your suggestion changes that.

> >Maybe an external tool to reassemble complete messages from
> >prefixed {{cookie}} message logs would be fine for awhile.
> >
> >Perhaps something like:
> >
> >cookie = printk_block_start()
> >printk_block[s](cookie)
> >printk_block_end(cookie)?
> >
> >where printk_block emits cookie when multiple cookies
> >are active.
> 
> How is this supposed to work? Are you suggesting that the printk buffer is
> locked?

No, just another identifier placed into logs that allow messages
to be reassembled into something readable when multiple printk_block's
are active.

> Now, if you hold the output of a printk block until it's _end()
> counterpart is executed, the user does not get any output when the
> machine locks up during the for loop.

External tool scans logs.  No blocking or delay in output.

cheers,  Joe

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