linux-kernel - On "ratelimit: Use per ratelimit context locking"

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Date:	Sun, 20 Dec 2009 12:39:39 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Ingo Molnar <mingo@...e.hu>
CC:	linux-kernel@...r.kernel.org, Jay Fenlason <fenlason@...hat.com>
Subject: On "ratelimit: Use per ratelimit context locking"

Hi Ingo,

in pre 2.6.33-rc1 commit 979f693d you wrote: "I'd like to use
printk_ratelimit() in atomic context, but that's not possible right now
due to the spinlock usage this commit introduced more than a year ago:
717115e: printk ratelimiting rewrite".¹,²

By not possible, do you mean it would be an outright bug to call
printk_ratelimit in atomic context prior to 979f693d, or merely a
performance issue?  If the former, under which circumstances would the
bug hit?

I'm asking because one of my commits actually introduced a
printk_ratelimit use in an interrupt handler shortly before 2.6.32 was
released.  In my testing, it didn't occur to me that there might be a
problem.

¹http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=979f693def9084a452846365dfde5dcb28366333
²http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=717115e1a5856b57af0f71e1df7149108294fc10
-- 
Stefan Richter
-=====-==--= ==-- =-=--
http://arcgraph.de/sr/
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