linux-kernel - Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers

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Date:	Thu, 05 Aug 2010 12:03:05 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Jason Wessel <jason.wessel@...driver.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	David Airlie <airlied@...ux.ie>,
	David Miller <davem@...emloft.net>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Russell King <linux@....linux.org.uk>,
	Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops
 handlers

On Wed, 2010-08-04 at 07:03 -0500, Jason Wessel wrote:
> The usb serial has the same kind of problem with all sorts of locks.
> I
> had resorted to using a tasklet or workqueue to get the sysrq to
> execute
> just outside the usb serial driver context.  This work never made it
> upstream because it was part of another series, but the reference is:
> http://lkml.org/lkml/2010/3/9/17
> 
> For the standard serial you might be able to get away with dropping
> the
> lock for the sysrq.
> 
> Did you have a particular way to trigger the problem or was it just
> completely random, because I don't know that I have observed this
> behavior with the typical 8250 driver.

Yes, I do actually :-) A 64-way machine and a bunch of processes
flooding the console will do it just fine :-)

Cheers,
Ben.


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