2016-03-18 08:30:41

by Vishal Thanki

Subject: [PATCH v3] rt2x00usb: Use usb anchor to manage URB

With current driver, it is observed that a URB is not
completed while the USB disconnect is initiated. Due to
that, the URB completion hanlder is trying to access
the resource which was freed as a part of USB disconnect.
Managing the URBs with anchor will make sure that all
the URBs are handled gracefully before device gets
disconnected.

Signed-off-by: Vishal Thanki <[email protected]>
---
drivers/net/wireless/ralink/rt2x00/rt2x00.h | 3 +++
drivers/net/wireless/ralink/rt2x00/rt2x00usb.c | 23 +++++++++++++++++++++--
2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00.h b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
index 3282ddb..9426c75 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00.h
@@ -38,6 +38,7 @@
#include <linux/kfifo.h>
#include <linux/hrtimer.h>
#include <linux/average.h>
+#include <linux/usb.h>

#include <net/mac80211.h>

@@ -1001,6 +1002,8 @@ struct rt2x00_dev {

/* Extra TX headroom required for alignment purposes. */
unsigned int extra_tx_headroom;
+
+ struct usb_anchor *anchor;
};

struct rt2x00_bar_list_entry {
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
index 7627af6..bba1430 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00usb.c
@@ -171,8 +171,11 @@ static void rt2x00usb_register_read_async_cb(struct urb *urb)
{
struct rt2x00_async_read_data *rd = urb->context;
if (rd->callback(rd->rt2x00dev, urb->status, le32_to_cpu(rd->reg))) {
- if (usb_submit_urb(urb, GFP_ATOMIC) < 0)
+ usb_anchor_urb(urb, rd->rt2x00dev->anchor);
+ if (usb_submit_urb(urb, GFP_ATOMIC) < 0) {
+ usb_unanchor_urb(urb);
kfree(rd);
+ }
} else
kfree(rd);
}
@@ -206,8 +209,11 @@ void rt2x00usb_register_read_async(struct rt2x00_dev *rt2x00dev,
usb_fill_control_urb(urb, usb_dev, usb_rcvctrlpipe(usb_dev, 0),
(unsigned char *)(&rd->cr), &rd->reg, sizeof(rd->reg),
rt2x00usb_register_read_async_cb, rd);
- if (usb_submit_urb(urb, GFP_ATOMIC) < 0)
+ usb_anchor_urb(urb, rt2x00dev->anchor);
+ if (usb_submit_urb(urb, GFP_ATOMIC) < 0) {
+ usb_unanchor_urb(urb);
kfree(rd);
+ }
usb_free_urb(urb);
}
EXPORT_SYMBOL_GPL(rt2x00usb_register_read_async);
@@ -313,8 +319,10 @@ static bool rt2x00usb_kick_tx_entry(struct queue_entry *entry, void *data)
entry->skb->data, length,
rt2x00usb_interrupt_txdone, entry);

+ usb_anchor_urb(entry_priv->urb, rt2x00dev->anchor);
status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
if (status) {
+ usb_unanchor_urb(entry_priv->urb);
if (status == -ENODEV)
clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
@@ -402,8 +410,10 @@ static bool rt2x00usb_kick_rx_entry(struct queue_entry *entry, void *data)
entry->skb->data, entry->skb->len,
rt2x00usb_interrupt_rxdone, entry);

+ usb_anchor_urb(entry_priv->urb, rt2x00dev->anchor);
status = usb_submit_urb(entry_priv->urb, GFP_ATOMIC);
if (status) {
+ usb_unanchor_urb(entry_priv->urb);
if (status == -ENODEV)
clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
set_bit(ENTRY_DATA_IO_FAILED, &entry->flags);
@@ -734,6 +744,8 @@ void rt2x00usb_uninitialize(struct rt2x00_dev *rt2x00dev)
{
struct data_queue *queue;

+ usb_kill_anchored_urbs(rt2x00dev->anchor);
+
queue_for_each(rt2x00dev, queue)
rt2x00usb_free_entries(queue);
}
@@ -818,6 +830,13 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
if (retval)
goto exit_free_reg;

+ rt2x00dev->anchor = devm_kmalloc(&usb_dev->dev,
+ sizeof(struct usb_anchor),
+ GFP_KERNEL);
+ if (!rt2x00dev->anchor)
+ goto exit_free_reg;
+
+ init_usb_anchor(rt2x00dev->anchor);
return 0;

exit_free_reg:
--
2.4.3

2016-03-18 10:31:47

by Stanislaw Gruszka

Subject: Re: [PATCH v3] rt2x00usb: Use usb anchor to manage URB

On Fri, Mar 18, 2016 at 09:30:36AM +0100, Vishal Thanki wrote:
> @@ -734,6 +744,8 @@ void rt2x00usb_uninitialize(struct rt2x00_dev *rt2x00dev)
> {
> struct data_queue *queue;
>
> + usb_kill_anchored_urbs(rt2x00dev->anchor);

As already pointed in different email this is not good place either ...

This should be placed in rt2x00lib_remove_dev() i.e:

if (rt2x00_is_usb(rt2x00dev)) {
usb_kill_anchored_urbs(rt2x00dev->anchor);
hrtimer_cancel(&rt2x00dev->txstatus_timer);
cancel_work_sync(&rt2x00dev->rxdone_work);
cancel_work_sync(&rt2x00dev->txdone_work);
}

Since queues are flushed, hrtimer and works will not rearm, so
this should be enough to stop the driver properly.

Stanislaw