From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: Locking in the clk API
Date: Thu, 27 Jan 2011 21:11:51 +0000 [thread overview]
Message-ID: <20110127211151.GC1597@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20110127210729.79eef2c1@lxorguk.ukuu.org.uk>
On Thu, Jan 27, 2011 at 09:07:29PM +0000, Alan Cox wrote:
> > > For internal tree purposes, does .set_termios need to be atomic? Can it
> > > grab mutexes instead of spinlock?
> >
> > I think I already answered that question above where I said "protect
> > against the interrupt handler accessing the port->* stuff".
>
> I'm not sure you answered it correctly however as the locking nowdays is
> a bit different.
>
> Architecturally the termios handling doesn't need a spin lock nor is it
> called under one. In fact it's vital this is the case because of USB.
It needs to protect against the read_status_mask and ignore_status_mask
being read half-way through an update by the interrupt handler, otherwise
you can end up with god-knows-what coming through from each termios
change.
Eg, you could see an effective CREAD flip when the state of CREAD wasn't
actually changed.
next prev parent reply other threads:[~2011-01-27 21:11 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-11 2:16 Locking in the clk API Jeremy Kerr
2011-01-11 3:15 ` Paul Mundt
2011-01-11 4:11 ` Jeremy Kerr
2011-01-11 4:54 ` Paul Mundt
2011-01-20 16:32 ` Ben Dooks
2011-01-20 18:57 ` Russell King - ARM Linux
2011-01-21 3:43 ` Saravana Kannan
2011-01-21 9:31 ` Russell King - ARM Linux
2011-01-11 9:03 ` Sascha Hauer
2011-01-11 9:28 ` Russell King - ARM Linux
2011-01-11 14:34 ` Pavel Machek
2011-01-20 16:29 ` Ben Dooks
2011-01-20 18:56 ` Russell King - ARM Linux
2011-01-20 21:30 ` Nicolas Pitre
2011-01-21 2:06 ` Dima Zavin
2011-01-21 4:12 ` Saravana Kannan
2011-01-21 9:32 ` Russell King - ARM Linux
2011-01-22 1:53 ` Saravana Kannan
2011-01-22 2:24 ` Colin Cross
2011-01-22 2:56 ` Saravana Kannan
2011-01-22 9:15 ` Russell King - ARM Linux
2011-01-24 19:31 ` Saravana Kannan
2011-01-21 21:03 ` Dima Zavin
2011-01-21 21:53 ` Nicolas Pitre
2011-01-21 22:02 ` Russell King - ARM Linux
2011-01-21 22:28 ` Colin Cross
2011-01-21 23:21 ` Benjamin Herrenschmidt
2011-01-21 23:50 ` Nicolas Pitre
2011-01-22 1:35 ` Saravana Kannan
2011-01-22 2:22 ` Colin Cross
2011-01-21 22:29 ` Nicolas Pitre
2011-01-21 23:28 ` Bryan Huntsman
2011-01-11 9:16 ` Russell King - ARM Linux
2011-01-11 9:44 ` Jeremy Kerr
2011-01-11 10:13 ` Paul Mundt
2011-01-11 10:30 ` Jeremy Kerr
2011-01-11 12:18 ` Paul Mundt
2011-01-11 13:52 ` Uwe Kleine-König
2011-01-11 14:35 ` Jeremy Kerr
2011-01-12 3:25 ` Saravana Kannan
2011-01-12 7:40 ` Uwe Kleine-König
2011-01-12 1:54 ` Saravana Kannan
2011-01-12 2:25 ` Paul Mundt
2011-01-20 16:57 ` Ben Dooks
2011-01-20 16:53 ` Ben Dooks
2011-01-20 16:40 ` Ben Dooks
2011-01-11 10:39 ` Uwe Kleine-König
2011-01-11 10:47 ` Russell King - ARM Linux
2011-01-11 10:56 ` Uwe Kleine-König
2011-01-11 11:15 ` Richard Zhao
2011-01-20 17:02 ` Ben Dooks
2011-01-20 19:08 ` Russell King - ARM Linux
2011-01-21 0:09 ` Jassi Brar
2011-01-21 4:47 ` Jassi Brar
2011-01-21 9:39 ` Russell King - ARM Linux
2011-01-21 10:11 ` Jassi Brar
2011-01-22 4:08 ` Richard Zhao
2011-01-22 5:30 ` Jassi Brar
2011-01-21 7:16 ` Saravana Kannan
2011-01-21 9:40 ` Russell King - ARM Linux
2011-01-22 1:47 ` Saravana Kannan
2011-01-27 4:34 ` Saravana Kannan
2011-01-27 8:54 ` Russell King - ARM Linux
2011-01-27 20:30 ` Saravana Kannan
2011-01-27 20:43 ` Russell King - ARM Linux
2011-01-27 21:07 ` Alan Cox
2011-01-27 21:11 ` Russell King - ARM Linux [this message]
2011-01-27 21:15 ` Russell King - ARM Linux
2011-01-28 3:29 ` Saravana Kannan
2011-01-28 3:27 ` Saravana Kannan
2011-01-11 12:11 ` Jassi Brar
2011-01-12 2:56 ` Saravana Kannan
2011-01-12 9:03 ` Russell King - ARM Linux
2011-01-15 14:02 ` Christer Weinigel
2011-01-15 14:53 ` Russell King - ARM Linux
2011-01-15 15:03 ` Uwe Kleine-König
2011-01-15 15:15 ` Russell King - ARM Linux
2011-01-15 16:03 ` Uwe Kleine-König
2011-01-15 16:21 ` Russell King - ARM Linux
2011-01-15 16:31 ` Uwe Kleine-König
2011-01-16 6:59 ` Grant Likely
2011-01-15 17:07 ` Christer Weinigel
2011-01-15 17:20 ` Russell King - ARM Linux
2011-01-15 17:44 ` Christer Weinigel
2011-01-15 20:30 ` Russell King - ARM Linux
2011-01-17 1:19 ` Jeremy Kerr
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