linux-kernel - [PATCH v3 1/2] mcb: remove is_added flag from mcb

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Message-ID: <20230906114901.63174-2-JoseJavier.Rodriguez@duagon.com>
Date:   Wed, 6 Sep 2023 11:49:26 +0000
From:   Rodríguez Barbarin, José Javier 
        <JoseJavier.Rodriguez@...gon.com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jirislaby@...nel.org" <jirislaby@...nel.org>
CC:     "morbidrsa@...il.com" <morbidrsa@...il.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jth@...nel.org" <jth@...nel.org>,
        Sanjuán García, Jorge 
        <Jorge.SanjuanGarcia@...gon.com>,
        Sanjuán García, Jorge 
        <Jorge.SanjuanGarcia@...gon.com>,
        Rodríguez Barbarin, José Javier 
        <JoseJavier.Rodriguez@...gon.com>
Subject: [PATCH v3 1/2] mcb: remove is_added flag from mcb_device struct

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

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")
Signed-off-by: Jorge Sanjuan Garcia <jorge.sanjuangarcia@...gon.com>
Co-developed-by: Jose Javier Rodriguez Barbarin <JoseJavier.Rodriguez@...gon.com>
Signed-off-by: Jose Javier Rodriguez Barbarin <JoseJavier.Rodriguez@...gon.com>
---
 drivers/mcb/mcb-core.c  | 10 +++-------
 drivers/mcb/mcb-parse.c |  2 --
 include/linux/mcb.h     |  1 -
 3 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/mcb/mcb-core.c b/drivers/mcb/mcb-core.c
index 978fdfc19a06..0cac5bead84f 100644
--- 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;
 }
diff --git a/drivers/mcb/mcb-parse.c b/drivers/mcb/mcb-parse.c
index 2aef990f379f..656b6b71c768 100644
--- a/drivers/mcb/mcb-parse.c
+++ b/drivers/mcb/mcb-parse.c
@@ -99,8 +99,6 @@ static int chameleon_parse_gdd(struct mcb_bus *bus,
 	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;
diff --git a/include/linux/mcb.h b/include/linux/mcb.h
index 1e5893138afe..0b971b24a804 100644
--- a/include/linux/mcb.h
+++ b/include/linux/mcb.h
@@ -63,7 +63,6 @@ static inline struct mcb_bus *to_mcb_bus(struct device *dev)
 struct mcb_device {
 	struct device dev;
 	struct mcb_bus *bus;
-	bool is_added;
 	struct mcb_driver *driver;
 	u16 id;
 	int inst;
-- 
2.34.1