linux-kernel - Re: [PATCH] libata: Register for dock events when the drive is inside a dock station

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Message-ID: <20080228233610.GA3808@homac>
Date:	Fri, 29 Feb 2008 00:36:11 +0100
From:	Holger Macht <hmacht@...e.de>
To:	Tejun Heo <htejun@...il.com>, Jeff Garzik <jeff@...zik.org>,
	linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
	Kristen Carlson Accardi <kristen.c.accardi@...el.com>
Subject: Re: [PATCH] libata: Register for dock events when the drive is
	inside a dock station

On Thu 28. Feb - 19:32:43, Holger Macht wrote:
> On Thu 28. Feb - 16:58:17, Holger Macht wrote:
> > On Thu 28. Feb - 22:05:53, Tejun Heo wrote:
> > > Holger Macht wrote:
> > > > On Thu 28. Feb - 18:35:06, Tejun Heo wrote:
> > > >> Holger Macht wrote:
> > > >>> The hotplug handler is only called if the device is actually inside the
> > > >>> dock station. If it is not, nothing will happen. I hope that I got your
> > > >>> question right?
> > > >> Yes, right.
> > > >>
> > > >>> However, if this would be helpful, it would be easy to add something like
> > > >>> a am_I_on_dock_station?(...) function to the dock driver.
> > > >> Hmm.. as long as the event is only delivered when the device is actually
> > > >> connected behind dock, I think it's okay.
> > > > 
> > > > The dock driver also export a is_dock_device(acpi_handle) function, which
> > > > could be used to make more fine-grained decisions, but it shouldn't be
> > > > needed here.
> > > > 
> > > >> Does the attached patch fix the previous undock problem?  It now
> > > >> explicitly tells libata EH to detach the notified devices on
> > > >> EJECT_REQUEST and wait for EH to complete such that control is returned
> > > >> to ACPI after all notified devices are actually detached.
> > > > 
> > > > No it does not. Apparently, it freezes faster (from 1 second down to
> > > > immediately). Before, it just froze when someone (in this case HAL) tried
> > > > to access the device. The "echo 1 > undock" call does not even return, so
> > > > it might have introduced another problem.
> > > 
> > > The code should be in generally right direction.  Can you be persuaded
> > > into tracking down what's going on?
> > 
> > I had a quick glance with adding some printk's. Now I got a different
> > behaviour once. System did not freeze, but were certainly confused. The
> > last thing which got printed to messages was exactly before
> > spin_lock_irqsave(ap->lock, flags); at the beginning of ata_acpi_handle_hotplug(...)
> > 
> > The printk immediately after this call didn't come through anymore (with
> > being able to use the system for a short time afterwards).
> 
> Ok, it seems that there is something broken somewhere else in
> 2.6.25.rc3. Not sure at all if it's your patch freezing the machine. I'll
> give 2.6.24.3 a try...

So once again...

After applying your patch, I got the OOPS seen in attachment
'oops-undock-1'. After changing the following, which is hopefully
correct...

--- ../orig/linux-2.6.24.3/drivers/ata/libata-acpi.c	2008-02-29 00:31:44.000000000 +0100
+++ drivers/ata/libata-acpi.c	2008-02-29 00:32:26.000000000 +0100
@@ -123,7 +123,7 @@
 {
 	char event_string[12];
 	char *envp[] = { event_string, NULL };
-	struct ata_eh_info *ehi = &ap->link.eh_info;
+	struct ata_eh_info *ehi;
 	struct kobject *kobj = NULL;
 	int wait = 0;
 	unsigned long flags;
@@ -131,6 +131,8 @@
 	if (!ap)
 		ap = dev->link->ap;
 
+	ehi = &ap->link.eh_info;
+
 	spin_lock_irqsave(ap->lock, flags);
 
 	switch (event) {


...I got both an oops when docking (attachments oops-dock) and when undocking
(attachment oops-undock2).

Regards,
	Holger

View attachment "oops-undock-1" of type "text/plain" (2637 bytes)

View attachment "oops-dock" of type "text/plain" (4443 bytes)

View attachment "oops-undock-2" of type "text/plain" (7517 bytes)