From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
David Airlie <airlied@linux.ie>,
David Miller <davem@davemloft.net>,
Fenghua Yu <fenghua.yu@intel.com>,
Greg Kroah-Hartman <gregkh@suse.de>,
Jason Wessel <jason.wessel@windriver.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Russell King <linux@arm.linux.org.uk>,
Tony Luck <tony.luck@intel.com>
Subject: Re: [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers
Date: Thu, 05 Aug 2010 11:59:24 +1000 [thread overview]
Message-ID: <1280973564.1902.166.camel@pasglop> (raw)
In-Reply-To: <20100804100926.3f24f5e5@lxorguk.ukuu.org.uk>
On Wed, 2010-08-04 at 10:09 +0100, Alan Cox wrote:
>
> 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)
Right. That's nasty. I think we need somewhat to break the loop when
that happens as if we were getting a new interrupt to some extent.
And that's a lot of drivers to fix.
> > 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.
Interesting idea. That does mean that multiple sysrq in one interrupt
will be coalesced but I don't see that as an issue.
> Otherwise it'll be a huge amount of work to even build test all those
> consoles.
Right. Better to have a way where we can fix them one at a time. I'll
look into it. Thanks.
Cheers,
Ben.
next prev parent reply other threads:[~2010-08-05 2:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-04 7:58 [PATCH 0/3] SysRq: do not pass tty argument around Dmitry Torokhov
2010-08-04 7:59 ` [PATCH 1/3] Input: sysrq - drop tty argument from sysrq ops handlers Dmitry Torokhov
2010-08-04 8:33 ` Benjamin Herrenschmidt
2010-08-04 9:09 ` Alan Cox
2010-08-05 1:59 ` Benjamin Herrenschmidt [this message]
2010-08-04 12:03 ` Jason Wessel
2010-08-05 2:03 ` Benjamin Herrenschmidt
2010-08-04 7:59 ` [PATCH 2/3] Input: sysrq - drop tty argument form handle_sysrq() Dmitry Torokhov
2010-08-04 11:25 ` Jason Wessel
2010-08-04 7:59 ` [PATCH 3/3] USB: drop tty argument from usb_serial_handle_sysrq_char() Dmitry Torokhov
2010-08-04 11:25 ` Jason Wessel
2010-08-04 9:11 ` [PATCH 0/3] SysRq: do not pass tty argument around Alan Cox
2010-08-04 19:44 ` Greg KH
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