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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1280973564.1902.166.camel@pasglop \
--to=benh@kernel.crashing.org \
--cc=airlied@linux.ie \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=davem@davemloft.net \
--cc=dmitry.torokhov@gmail.com \
--cc=fenghua.yu@intel.com \
--cc=gregkh@suse.de \
--cc=jason.wessel@windriver.com \
--cc=linux-input@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@arm.linux.org.uk \
--cc=schwidefsky@de.ibm.com \
--cc=tony.luck@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.