[PATCH] cxacru: Create sysfs attributes in atm_start instead of bind

[Simon Arlott <simon@fire.lp0.eu>]

Since usbatm doesn't set the usb_interface driver data until after calling bind 
and heavy_init, it would be NULL when the sysfs attributes are read. Reading the 
MAC address from atm_dev before atm_dev exists would have been be possible too.

Calling create_device_file in atm_start will avoid this problem, and the data 
is useless until the first status poll runs. However, it must be ready before a 
status poll does a printk on line status change otherwise userspace could react 
before the files exist.

For completeness I've moved remove_device_file to atm_stop so it's not called in 
unbind when it's not needed. There's no point starting ADSL if atm_start could 
still fail either.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Duncan Sands <duncan.sands@math.u-psud.fr>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
This bug find is from the "waiting for my toast to toast" category.

> #undef CXACRU_DEVICE_REVOVE_FILE
Oops.

drivers/usb/atm/cxacru.c |   45 +++++++++++++++++++++++++--------------------
1 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/drivers/usb/atm/cxacru.c b/drivers/usb/atm/cxacru.c
index 0b12ace..4ecb4c7 100644
--- a/drivers/usb/atm/cxacru.c
+++ b/drivers/usb/atm/cxacru.c
@@ -618,10 +618,22 @@ static int cxacru_card_status(struct cxacru_data *instance)
	return 0;
}

+static void cxacru_remove_device_files(struct usbatm_data *usbatm_instance,
+		struct atm_dev *atm_dev)
+{
+	struct usb_interface *intf = usbatm_instance->usb_intf;
+
+	#define CXACRU_DEVICE_REMOVE_FILE(_name) \
+		device_remove_file(&intf->dev, &dev_attr_##_name);
+	CXACRU_ALL_FILES(REMOVE);
+	#undef CXACRU_DEVICE_REMOVE_FILE
+}
+
static int cxacru_atm_start(struct usbatm_data *usbatm_instance,
		struct atm_dev *atm_dev)
{
	struct cxacru_data *instance = usbatm_instance->driver_data;
+	struct usb_interface *intf = usbatm_instance->usb_intf;
	/*
	struct atm_dev *atm_dev = usbatm_instance->atm_dev;
	*/
@@ -638,6 +650,13 @@ static int cxacru_atm_start(struct usbatm_data *usbatm_instance,
		return ret;
	}

+	#define CXACRU_DEVICE_CREATE_FILE(_name) \
+		ret = device_create_file(&intf->dev, &dev_attr_##_name); \
+		if (unlikely(ret)) \
+			goto fail_sysfs;
+	CXACRU_ALL_FILES(CREATE);
+	#undef CXACRU_DEVICE_CREATE_FILE
+
	/* start ADSL */
	mutex_lock(&instance->adsl_state_serialize);
	ret = cxacru_cm(instance, CM_REQUEST_CHIP_ADSL_LINE_START, NULL, 0, NULL, 0);
@@ -669,6 +688,11 @@ static int cxacru_atm_start(struct usbatm_data *usbatm_instance,
	if (start_polling)
		cxacru_poll_status(&instance->poll_work.work);
	return 0;
+
+fail_sysfs:
+	usb_err(usbatm_instance, "cxacru_atm_start: device_create_file failed (%d)\n", ret);
+	cxacru_remove_device_files(usbatm_instance, atm_dev);
+	return ret;
}

static void cxacru_poll_status(struct work_struct *work)
@@ -1054,13 +1078,6 @@ static int cxacru_bind(struct usbatm_data *usbatm_instance,
		goto fail;
	}

-	#define CXACRU_DEVICE_CREATE_FILE(_name) \
-		ret = device_create_file(&intf->dev, &dev_attr_##_name); \
-		if (unlikely(ret)) \
-			goto fail_sysfs;
-	CXACRU_ALL_FILES(CREATE);
-	#undef CXACRU_DEVICE_CREATE_FILE
-
	usb_fill_int_urb(instance->rcv_urb,
			usb_dev, usb_rcvintpipe(usb_dev, CXACRU_EP_CMD),
			instance->rcv_buf, PAGE_SIZE,
@@ -1081,14 +1098,6 @@ static int cxacru_bind(struct usbatm_data *usbatm_instance,

	return 0;

- fail_sysfs:
-	dbg("cxacru_bind: device_create_file failed (%d)\n", ret);
-
-	#define CXACRU_DEVICE_REMOVE_FILE(_name) \
-		device_remove_file(&intf->dev, &dev_attr_##_name);
-	CXACRU_ALL_FILES(REMOVE);
-	#undef CXACRU_DEVICE_REVOVE_FILE
-
 fail:
	free_page((unsigned long) instance->snd_buf);
	free_page((unsigned long) instance->rcv_buf);
@@ -1135,11 +1144,6 @@ static void cxacru_unbind(struct usbatm_data *usbatm_instance,
	free_page((unsigned long) instance->snd_buf);
	free_page((unsigned long) instance->rcv_buf);

-	#define CXACRU_DEVICE_REMOVE_FILE(_name) \
-		device_remove_file(&intf->dev, &dev_attr_##_name);
-	CXACRU_ALL_FILES(REMOVE);
-	#undef CXACRU_DEVICE_REVOVE_FILE
-
	kfree(instance);

	usbatm_instance->driver_data = NULL;
@@ -1220,6 +1224,7 @@ static struct usbatm_driver cxacru_driver = {
	.heavy_init	= cxacru_heavy_init,
	.unbind		= cxacru_unbind,
	.atm_start	= cxacru_atm_start,
+	.atm_stop	= cxacru_remove_device_files,
	.bulk_in	= CXACRU_EP_DATA,
	.bulk_out	= CXACRU_EP_DATA,
	.rx_padding	= 3,
--
1.5.0.1

--
Simon Arlott
-
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