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

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Date:	Wed, 4 Aug 2010 10:09:26 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
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>,
	Jason Wessel <jason.wessel@...driver.com>,
	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

> I have a patch to drop the lock in serial_core.h, I'll post that
> tomorrow hopefully, just checking if there's any objection there ? The

Fundamentally - no. However the impact it has on a lot of the drivers
will be significant and you'll be submitting a huge patch pile to fix up
all the locking assumptions (for one it means port->tty might change
across any call that ends up in sysrq)

> serial drivers might need to be audited a bit to make sure they cope
> with the lock being dropped and re-acquired around the sysrq call.

Architecturally I think it would make more sense to add a new sysrq
helper which merely sets a flag, and check that flag at the end of the IRQ
when dropping the lock anyway.

Otherwise it'll be a huge amount of work to even build test all those
consoles.

Alan
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