Hi Paul, Peter,
On Mon, Nov 12, 2012 at 11:31:15AM -0600, Peter Tyser wrote:
> Thanks for reporting the issue!
>
> On Fri, 2012-11-09 at 14:19 +0100, Paul Bolle wrote:
> > 0) I can trigger a NULL pointer dereference if I remove the lpc_ich
> > module. This seems to only happen if I remove it for the second time
> > (ie, remove the module, insert it and remove it again). This happens
> > both on i686 and x86_64 (different setups, as inserting the module
> > triggers different messages about the initialization of the MFD cells on
> > these machines). Both machines are running v3.6.6.
>
> I believe this is caused by the fact that non-MFD devices get attached
> to the same parent as the iTCO_wdt driver, which is an MFD. When the
> MFD code attempts unregister the MFD drivers, it oops when the non-MFD
> devices are accessed since they don't have the mfd_cell node.
That's probably correct. I just merged commit
5dc4dda91c86ef82bd53d77e5de50ec095b33e46 into my for-next branch and that one
could fix that issue. Could you guys please give it a go ? This is the actual
patch:
>From 5dc4dda91c86ef82bd53d77e5de50ec095b33e46 Mon Sep 17 00:00:00 2001
From: Charles Keepax <ckee...@opensource.wolfsonmicro.com>
Date: Fri, 9 Nov 2012 16:15:28 +0000
Subject: [PATCH] mfd: Only unregister platform devices allocated by the mfd
core
mfd_remove_devices would iterate over all devices sharing a parent with
an mfd device regardless of whether they were allocated by the mfd core
or not. This especially caused problems when the device structure was
not contained within a platform_device, because to_platform_device is
used on each device pointer.
This patch defines a device_type for mfd devices and checks this is
present from mfd_remove_devices_fn before processing the device.
Signed-off-by: Charles Keepax <ckee...@opensource.wolfsonmicro.com>
Reviewed-by: Mark Brown <broo...@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sa...@linux.intel.com>
---
drivers/mfd/mfd-core.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index f8b7771..7604f4e 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -21,6 +21,10 @@
#include <linux/irqdomain.h>
#include <linux/of.h>
+static struct device_type mfd_dev_type = {
+ .name = "mfd_device",
+};
+
int mfd_cell_enable(struct platform_device *pdev)
{
const struct mfd_cell *cell = mfd_get_cell(pdev);
@@ -91,6 +95,7 @@ static int mfd_add_device(struct device *parent, int id,
goto fail_device;
pdev->dev.parent = parent;
+ pdev->dev.type = &mfd_dev_type;
if (parent->of_node && cell->of_compatible) {
for_each_child_of_node(parent->of_node, np) {
@@ -204,10 +209,16 @@ EXPORT_SYMBOL(mfd_add_devices);
static int mfd_remove_devices_fn(struct device *dev, void *c)
{
- struct platform_device *pdev = to_platform_device(dev);
- const struct mfd_cell *cell = mfd_get_cell(pdev);
+ struct platform_device *pdev;
+ const struct mfd_cell *cell;
atomic_t **usage_count = c;
+ if (dev->type != &mfd_dev_type)
+ return 0;
+
+ pdev = to_platform_device(dev);
+ cell = mfd_get_cell(pdev);
+
/* find the base address of usage_count pointers (for freeing) */
if (!*usage_count || (cell->usage_count < *usage_count))
*usage_count = cell->usage_count;
--
1.7.10.4
--
Intel Open Source Technology Centre
http://oss.intel.com/
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