* [PATCH] cbus-tahvo: Add tahvo_write_reg locking
@ 2011-11-05 16:19 Michael Büsch
2011-11-07 6:10 ` Felipe Balbi
0 siblings, 1 reply; 4+ messages in thread
From: Michael Büsch @ 2011-11-05 16:19 UTC (permalink / raw)
To: Tony Lindgren; +Cc: Felipe Balbi, linux-omap
tahvo_write_reg() needs to take the mutex to avoid a race
condition with tahvo_set_clear_reg_bits:
tahvo_set_clear_reg_bits(): | tahvo_write_reg():
__tahvo_read_reg() |
| __tahvo_write_reg() <-- race here
__tahvo_write_reg() |
Signed-off-by: Michael Buesch <m@bues.ch>
---
Index: linux-3.1/drivers/cbus/tahvo.c
===================================================================
--- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119 +0100
+++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100
@@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil
{
struct tahvo *tahvo = dev_get_drvdata(child->parent);
+ mutex_lock(&tahvo->mutex);
__tahvo_write_reg(tahvo, reg, val);
+ mutex_unlock(&tahvo->mutex);
}
EXPORT_SYMBOL(tahvo_write_reg);
--
Greetings, Michael.
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] cbus-tahvo: Add tahvo_write_reg locking
2011-11-05 16:19 [PATCH] cbus-tahvo: Add tahvo_write_reg locking Michael Büsch
@ 2011-11-07 6:10 ` Felipe Balbi
2011-11-07 9:18 ` Michael Büsch
0 siblings, 1 reply; 4+ messages in thread
From: Felipe Balbi @ 2011-11-07 6:10 UTC (permalink / raw)
To: Michael Büsch; +Cc: Tony Lindgren, Felipe Balbi, linux-omap
[-- Attachment #1: Type: text/plain, Size: 1100 bytes --]
Hi,
On Sat, Nov 05, 2011 at 05:19:54PM +0100, Michael Büsch wrote:
> tahvo_write_reg() needs to take the mutex to avoid a race
> condition with tahvo_set_clear_reg_bits:
>
> tahvo_set_clear_reg_bits(): | tahvo_write_reg():
> __tahvo_read_reg() |
> | __tahvo_write_reg() <-- race here
> __tahvo_write_reg() |
>
> Signed-off-by: Michael Buesch <m@bues.ch>
>
> ---
>
> Index: linux-3.1/drivers/cbus/tahvo.c
> ===================================================================
> --- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119 +0100
> +++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100
> @@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil
> {
> struct tahvo *tahvo = dev_get_drvdata(child->parent);
>
> + mutex_lock(&tahvo->mutex);
> __tahvo_write_reg(tahvo, reg, val);
> + mutex_unlock(&tahvo->mutex);
yeah, my bad. The same should be done with tahvo_read_reg(). Care to
resend this patch adding the change to tahvo_read_reg() too...
--
balbi
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] cbus-tahvo: Add tahvo_write_reg locking
2011-11-07 6:10 ` Felipe Balbi
@ 2011-11-07 9:18 ` Michael Büsch
2011-11-07 9:27 ` Felipe Balbi
0 siblings, 1 reply; 4+ messages in thread
From: Michael Büsch @ 2011-11-07 9:18 UTC (permalink / raw)
To: balbi; +Cc: Tony Lindgren, linux-omap
On Mon, 7 Nov 2011 08:10:45 +0200
Felipe Balbi <balbi@ti.com> wrote:
> Hi,
>
> On Sat, Nov 05, 2011 at 05:19:54PM +0100, Michael Büsch wrote:
> > tahvo_write_reg() needs to take the mutex to avoid a race
> > condition with tahvo_set_clear_reg_bits:
> >
> > tahvo_set_clear_reg_bits(): | tahvo_write_reg():
> > __tahvo_read_reg() |
> > | __tahvo_write_reg() <-- race here
> > __tahvo_write_reg() |
> >
> > Signed-off-by: Michael Buesch <m@bues.ch>
> >
> > ---
> >
> > Index: linux-3.1/drivers/cbus/tahvo.c
> > ===================================================================
> > --- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119 +0100
> > +++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100
> > @@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil
> > {
> > struct tahvo *tahvo = dev_get_drvdata(child->parent);
> >
> > + mutex_lock(&tahvo->mutex);
> > __tahvo_write_reg(tahvo, reg, val);
> > + mutex_unlock(&tahvo->mutex);
>
> yeah, my bad. The same should be done with tahvo_read_reg(). Care to
> resend this patch adding the change to tahvo_read_reg() too...
I think tahvo_read_reg is fine without a lock.
read vs write is already atomic due to the cbus lock.
it's the same situation as for retu. where we also don't need the lock in retu_read_reg.
--
Greetings, Michael.
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] cbus-tahvo: Add tahvo_write_reg locking
2011-11-07 9:18 ` Michael Büsch
@ 2011-11-07 9:27 ` Felipe Balbi
0 siblings, 0 replies; 4+ messages in thread
From: Felipe Balbi @ 2011-11-07 9:27 UTC (permalink / raw)
To: Michael Büsch; +Cc: balbi, Tony Lindgren, linux-omap
[-- Attachment #1: Type: text/plain, Size: 1557 bytes --]
Hi,
On Mon, Nov 07, 2011 at 09:18:36AM +0000, Michael Büsch wrote:
> > On Sat, Nov 05, 2011 at 05:19:54PM +0100, Michael Büsch wrote:
> > > tahvo_write_reg() needs to take the mutex to avoid a race
> > > condition with tahvo_set_clear_reg_bits:
> > >
> > > tahvo_set_clear_reg_bits(): | tahvo_write_reg():
> > > __tahvo_read_reg() |
> > > | __tahvo_write_reg() <-- race here
> > > __tahvo_write_reg() |
> > >
> > > Signed-off-by: Michael Buesch <m@bues.ch>
> > >
> > > ---
> > >
> > > Index: linux-3.1/drivers/cbus/tahvo.c
> > > ===================================================================
> > > --- linux-3.1.orig/drivers/cbus/tahvo.c 2011-11-05 17:03:39.598846119 +0100
> > > +++ linux-3.1/drivers/cbus/tahvo.c 2011-11-05 17:04:36.274768324 +0100
> > > @@ -104,7 +104,9 @@ void tahvo_write_reg(struct device *chil
> > > {
> > > struct tahvo *tahvo = dev_get_drvdata(child->parent);
> > >
> > > + mutex_lock(&tahvo->mutex);
> > > __tahvo_write_reg(tahvo, reg, val);
> > > + mutex_unlock(&tahvo->mutex);
> >
> > yeah, my bad. The same should be done with tahvo_read_reg(). Care to
> > resend this patch adding the change to tahvo_read_reg() too...
>
> I think tahvo_read_reg is fine without a lock.
> read vs write is already atomic due to the cbus lock.
>
> it's the same situation as for retu. where we also don't need the lock
> in retu_read_reg.
ok then, makes sense.
FWIW:
Acked-by: Felipe Balbi <balbi@ti.com>
--
balbi
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-11-07 9:27 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-11-05 16:19 [PATCH] cbus-tahvo: Add tahvo_write_reg locking Michael Büsch
2011-11-07 6:10 ` Felipe Balbi
2011-11-07 9:18 ` Michael Büsch
2011-11-07 9:27 ` Felipe Balbi
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox