linux-kernel - [PATCH, revert] ACPI / scan: Revert scan handler check in acpi_bus

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Date:	Sat, 08 Jun 2013 02:55:07 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Tony Luck <tony.luck@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: [PATCH, revert] ACPI / scan: Revert scan handler check in acpi_bus_match()

On Friday, June 07, 2013 03:23:44 PM Tony Luck wrote:
> On Fri, Jun 7, 2013 at 5:51 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > Aaron Lu (1):
> >       ACPI / scan: do not match drivers against objects having scan handlers
> 
> This patch showed up in linux-next tag next-20130605 and appears to be the
> cause of a boot failure on my ia64 HP rx2600 system.  It panics with
> the message:
> 
> Kernel panic - not syncing: Unable to find SBA IOMMU: Try a generic or
> DIG kernel
> 
> Reverting this from next-20130605 fixes my problem and I can boot again.
> 
> So please don't pull.

Sorry about this.

I don't think we will find out what's wrong here before -rc5, so please apply
the appended revert.

Rafael


---
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Subject: ACPI / scan: Revert scan handler check in acpi_bus_match()

Commit 9f29ab1 (ACPI / scan: do not match drivers against objects
having scan handlers) introduced a boot regression on Tony's
ia64 HP rx2600.  Tony says:

  "It panics with the message:

   Kernel panic - not syncing: Unable to find SBA IOMMU: Try a generic or DIG kernel

   [...] my problem comes from arch/ia64/hp/common/sba_iommu.c
   where the code in sba_init() says:

        acpi_bus_register_driver(&acpi_sba_ioc_driver);
        if (!ioc_list) {

   but because of this change we never managed to call ioc_init()
   so ioc_list doesn't get set up, and we die."

Revert commit 9f29ab1 to avoid this breakage and we'll fix the
problem it attempted to address later.

Reported-by: Tony Luck <tony.luck@...il.com>
Cc: 3.9+ <stable@...r.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/acpi/scan.c |    4 ----
 1 file changed, 4 deletions(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -857,10 +857,6 @@ static int acpi_bus_match(struct device
 	struct acpi_device *acpi_dev = to_acpi_device(dev);
 	struct acpi_driver *acpi_drv = to_acpi_driver(drv);
 
-	/* Skip ACPI device objects with scan handlers attached. */
-	if (acpi_dev->handler)
-		return 0;
-
 	return acpi_dev->flags.match_driver
 		&& !acpi_match_device_ids(acpi_dev, acpi_drv->ids);
 }

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