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usbhid: prevent deadlock during timeout

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On some HCDs usb_unlink_urb() can directly call the
completion handler. That limits the spinlocks that can
be taken in the handler to locks not held while calling
usb_unlink_urb()
To prevent a race with resubmission, this patch exposes
usbcore's infrastructure for blocking submission, uses it
and so drops the lock without causing a race in usbhid.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2012-04-30 09:13:46 +02:00 committed by Greg Kroah-Hartman
parent 166cb70e97
commit 8815bb09af
3 changed files with 79 additions and 6 deletions
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61
drivers/hid/usbhid/hid-core.c
View file

@ -399,6 +399,16 @@ static int hid_submit_ctrl(struct hid_device *hid)
* Output interrupt completion handler.
*/
static int irq_out_pump_restart(struct hid_device *hid)
{
struct usbhid_device *usbhid = hid->driver_data;
if (usbhid->outhead != usbhid->outtail)
return hid_submit_out(hid);
else
return -1;
}
static void hid_irq_out(struct urb *urb)
{
struct hid_device *hid = urb->context;
@ -428,7 +438,7 @@ static void hid_irq_out(struct urb *urb)
else
usbhid->outtail = (usbhid->outtail + 1) & (HID_OUTPUT_FIFO_SIZE - 1);
if (usbhid->outhead != usbhid->outtail && !hid_submit_out(hid)) {
if (!irq_out_pump_restart(hid)) {
/* Successfully submitted next urb in queue */
spin_unlock_irqrestore(&usbhid->lock, flags);
return;
@ -443,6 +453,15 @@ static void hid_irq_out(struct urb *urb)
/*
* Control pipe completion handler.
*/
static int ctrl_pump_restart(struct hid_device *hid)
{
struct usbhid_device *usbhid = hid->driver_data;
if (usbhid->ctrlhead != usbhid->ctrltail)
return hid_submit_ctrl(hid);
else
return -1;
}
static void hid_ctrl(struct urb *urb)
{
@ -476,7 +495,7 @@ static void hid_ctrl(struct urb *urb)
else
usbhid->ctrltail = (usbhid->ctrltail + 1) & (HID_CONTROL_FIFO_SIZE - 1);
if (usbhid->ctrlhead != usbhid->ctrltail && !hid_submit_ctrl(hid)) {
if (!ctrl_pump_restart(hid)) {
/* Successfully submitted next urb in queue */
spin_unlock(&usbhid->lock);
return;
@ -535,11 +554,27 @@ static void __usbhid_submit_report(struct hid_device *hid, struct hid_report *re
* the queue is known to run
* but an earlier request may be stuck
* we may need to time out
* no race because this is called under
* no race because the URB is blocked under
* spinlock
*/
if (time_after(jiffies, usbhid->last_out + HZ * 5))
if (time_after(jiffies, usbhid->last_out + HZ * 5)) {
usb_block_urb(usbhid->urbout);
/* drop lock to not deadlock if the callback is called */
spin_unlock(&usbhid->lock);
usb_unlink_urb(usbhid->urbout);
spin_lock(&usbhid->lock);
usb_unblock_urb(usbhid->urbout);
/*
* if the unlinking has already completed
* the pump will have been stopped
* it must be restarted now
*/
if (!test_bit(HID_OUT_RUNNING, &usbhid->iofl))
if (!irq_out_pump_restart(hid))
set_bit(HID_OUT_RUNNING, &usbhid->iofl);
}
}
return;
}
@ -583,11 +618,25 @@ static void __usbhid_submit_report(struct hid_device *hid, struct hid_report *re
* the queue is known to run
* but an earlier request may be stuck
* we may need to time out
* no race because this is called under
* no race because the URB is blocked under
* spinlock
*/
if (time_after(jiffies, usbhid->last_ctrl + HZ * 5))
if (time_after(jiffies, usbhid->last_ctrl + HZ * 5)) {
usb_block_urb(usbhid->urbctrl);
/* drop lock to not deadlock if the callback is called */
spin_unlock(&usbhid->lock);
usb_unlink_urb(usbhid->urbctrl);
spin_lock(&usbhid->lock);
usb_unblock_urb(usbhid->urbctrl);
/*
* if the unlinking has already completed
* the pump will have been stopped
* it must be restarted now
*/
if (!test_bit(HID_CTRL_RUNNING, &usbhid->iofl))
if (!ctrl_pump_restart(hid))
set_bit(HID_CTRL_RUNNING, &usbhid->iofl);
}
}
}

21
drivers/usb/core/urb.c
View file

@ -680,6 +680,27 @@ void usb_unpoison_urb(struct urb *urb)
}
EXPORT_SYMBOL_GPL(usb_unpoison_urb);
/**
* usb_block_urb - reliably prevent further use of an URB
* @urb: pointer to URB to be blocked, may be NULL
*
* After the routine has run, attempts to resubmit the URB will fail
* with error -EPERM. Thus even if the URB's completion handler always
* tries to resubmit, it will not succeed and the URB will become idle.
*
* The URB must not be deallocated while this routine is running. In
* particular, when a driver calls this routine, it must insure that the
* completion handler cannot deallocate the URB.
*/
void usb_block_urb(struct urb *urb)
{
if (!urb)
return;
atomic_inc(&urb->reject);
}
EXPORT_SYMBOL_GPL(usb_block_urb);
/**
* usb_kill_anchored_urbs - cancel transfer requests en masse
* @anchor: anchor the requests are bound to

3
include/linux/usb.h
View file

@ -1369,6 +1369,7 @@ extern int usb_unlink_urb(struct urb *urb);
extern void usb_kill_urb(struct urb *urb);
extern void usb_poison_urb(struct urb *urb);
extern void usb_unpoison_urb(struct urb *urb);
extern void usb_block_urb(struct urb *urb);
extern void usb_kill_anchored_urbs(struct usb_anchor *anchor);
extern void usb_poison_anchored_urbs(struct usb_anchor *anchor);
extern void usb_unpoison_anchored_urbs(struct usb_anchor *anchor);
@ -1381,6 +1382,8 @@ extern struct urb *usb_get_from_anchor(struct usb_anchor *anchor);
extern void usb_scuttle_anchored_urbs(struct usb_anchor *anchor);
extern int usb_anchor_empty(struct usb_anchor *anchor);
#define usb_unblock_urb usb_unpoison_urb
/**
* usb_urb_dir_in - check if an URB describes an IN transfer
* @urb: URB to be checked