[PATCH 6.1 098/131] mcb: remove is_added flag from mcb_device struct

Greg Kroah-Hartman
2023-10-16T09:04:48Z

From: Jorge Sanjuan Garcia <jorge.sanjuangarcia@duagon.com>

commit 0f28ada1fbf0054557cddcdb93ad17f767105208 upstream.

When calling mcb_bus_add_devices(), both mcb devices and the mcb
bus will attempt to attach a device to a driver because they share
the same bus_type. This causes an issue when trying to cast the
container of the device to mcb_device struct using to_mcb_device(),
leading to a wrong cast when the mcb_bus is added. A crash occurs
when freing the ida resources as the bus numbering of mcb_bus gets
confused with the is_added flag on the mcb_device struct.

The only reason for this cast was to keep an is_added flag on the
mcb_device struct that does not seem necessary. The function
device_attach() handles already bound devices and the mcb subsystem
does nothing special with this is_added flag so remove it completely.

Fixes: 18d288198099 ("mcb: Correctly initialize the bus's device")
Cc: stable <stable@kernel.org>
Signed-off-by: Jorge Sanjuan Garcia <jorge.sanjuangarcia@duagon.com>
Co-developed-by: Jose Javier Rodriguez Barbarin <JoseJavier.Rodriguez@duagon.com>
Signed-off-by: Jose Javier Rodriguez Barbarin <JoseJavier.Rodriguez@duagon.com>
Link: https://lore.kernel.org/r/20230906114901.63174-2-JoseJavier.Rodriguez@duagon.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/mcb/mcb-core.c | 10 +++-------
drivers/mcb/mcb-parse.c | 2 --
include/linux/mcb.h | 1 -
3 files changed, 3 insertions(+), 10 deletions(-)

--- a/drivers/mcb/mcb-core.c
+++ b/drivers/mcb/mcb-core.c
@@ -387,17 +387,13 @@ EXPORT_SYMBOL_NS_GPL(mcb_free_dev, MCB);

static int __mcb_bus_add_devices(struct device *dev, void *data)
{
- struct mcb_device *mdev = to_mcb_device(dev);
int retval;

- if (mdev->is_added)
- return 0;
-
retval = device_attach(dev);
- if (retval < 0)
+ if (retval < 0) {
dev_err(dev, "Error adding device (%d)\n", retval);
-
- mdev->is_added = true;
+ return retval;
+ }

return 0;
}
--- a/drivers/mcb/mcb-parse.c
+++ b/drivers/mcb/mcb-parse.c
@@ -99,8 +99,6 @@ static int chameleon_parse_gdd(struct mc
mdev->mem.end = mdev->mem.start + size - 1;
mdev->mem.flags = IORESOURCE_MEM;

- mdev->is_added = false;
-
ret = mcb_device_register(bus, mdev);
if (ret < 0)
goto err;
--- a/include/linux/mcb.h
+++ b/include/linux/mcb.h
@@ -63,7 +63,6 @@ static inline struct mcb_bus *to_mcb_bus
struct mcb_device {
struct device dev;
struct mcb_bus *bus;
- bool is_added;
struct mcb_driver *driver;
u16 id;
int inst;