This patch (as1260) changes the pm_usage_cnt field in struct
usb_interface from an int to an atomic_t. This is so that drivers can
invoke the usb_autopm_get_interface_async() and
usb_autopm_put_interface_async() routines without locking and without
fear of corrupting the pm_usage_cnt value.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
This can wait for 2.6.32. It is likely to be superseded soon by
Rafael's new PM runtime framework anyway.
Index: usb-2.6/include/linux/usb.h
===================================================================
--- usb-2.6.orig/include/linux/usb.h
+++ usb-2.6/include/linux/usb.h
@@ -195,7 +195,7 @@ struct usb_interface {
struct device dev; /* interface specific device info */
struct device *usb_dev;
- int pm_usage_cnt; /* usage counter for autosuspend */
+ atomic_t pm_usage_cnt; /* usage counter for autosuspend */
struct work_struct reset_ws; /* for resets in atomic context */
};
#define to_usb_interface(d) container_of(d, struct usb_interface, dev)
@@ -551,13 +551,13 @@ extern void usb_autopm_put_interface_asy
static inline void usb_autopm_enable(struct usb_interface *intf)
{
- intf->pm_usage_cnt = 0;
+ atomic_set(&intf->pm_usage_cnt, 0);
usb_autopm_set_interface(intf);
}
static inline void usb_autopm_disable(struct usb_interface *intf)
{
- intf->pm_usage_cnt = 1;
+ atomic_set(&intf->pm_usage_cnt, 1);
usb_autopm_set_interface(intf);
}
Index: usb-2.6/drivers/usb/core/hub.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/hub.c
+++ usb-2.6/drivers/usb/core/hub.c
@@ -373,7 +373,7 @@ static void kick_khubd(struct usb_hub *h
unsigned long flags;
/* Suppress autosuspend until khubd runs */
- to_usb_interface(hub->intfdev)->pm_usage_cnt = 1;
+ atomic_set(&to_usb_interface(hub->intfdev)->pm_usage_cnt, 1);
spin_lock_irqsave(&hub_event_lock, flags);
if (!hub->disconnected && list_empty(&hub->event_list)) {
@@ -678,7 +678,8 @@ static void hub_activate(struct usb_hub
msecs_to_jiffies(delay));
/* Suppress autosuspend until init is done */
- to_usb_interface(hub->intfdev)->pm_usage_cnt = 1;
+ atomic_set(&to_usb_interface(hub->intfdev)->
+ pm_usage_cnt, 1);
return; /* Continues at init2: below */
} else {
hub_power_on(hub, true);
Index: usb-2.6/drivers/usb/core/driver.c
===================================================================
--- usb-2.6.orig/drivers/usb/core/driver.c
+++ usb-2.6/drivers/usb/core/driver.c
@@ -235,7 +235,7 @@ static int usb_probe_interface(struct de
/* The interface should always appear to be in use
* unless the driver suports autosuspend.
*/
- intf->pm_usage_cnt = !(driver->supports_autosuspend);
+ atomic_set(&intf->pm_usage_cnt, !driver->supports_autosuspend);
/* Carry out a deferred switch to altsetting 0 */
if (intf->needs_altsetting0) {
@@ -347,7 +347,7 @@ int usb_driver_claim_interface(struct us
usb_pm_lock(udev);
iface->condition = USB_INTERFACE_BOUND;
mark_active(iface);
- iface->pm_usage_cnt = !(driver->supports_autosuspend);
+ atomic_set(&iface->pm_usage_cnt, !driver->supports_autosuspend);
usb_pm_unlock(udev);
/* if interface was already added, bind now; else let
@@ -1068,7 +1068,7 @@ static int autosuspend_check(struct usb_
intf = udev->actconfig->interface[i];
if (!is_active(intf))
continue;
- if (intf->pm_usage_cnt > 0)
+ if (atomic_read(&intf->pm_usage_cnt) > 0)
return -EBUSY;
if (intf->needs_remote_wakeup &&
!udev->do_remote_wakeup) {
@@ -1464,17 +1464,19 @@ static int usb_autopm_do_interface(struc
status = -ENODEV;
else {
udev->auto_pm = 1;
- intf->pm_usage_cnt += inc_usage_cnt;
+ atomic_add(inc_usage_cnt, &intf->pm_usage_cnt);
udev->last_busy = jiffies;
- if (inc_usage_cnt >= 0 && intf->pm_usage_cnt > 0) {
+ if (inc_usage_cnt >= 0 &&
+ atomic_read(&intf->pm_usage_cnt) > 0) {
if (udev->state == USB_STATE_SUSPENDED)
status = usb_resume_both(udev,
PMSG_AUTO_RESUME);
if (status != 0)
- intf->pm_usage_cnt -= inc_usage_cnt;
+ atomic_sub(inc_usage_cnt, &intf->pm_usage_cnt);
else
udev->last_busy = jiffies;
- } else if (inc_usage_cnt <= 0 && intf->pm_usage_cnt <= 0) {
+ } else if (inc_usage_cnt <= 0 &&
+ atomic_read(&intf->pm_usage_cnt) <= 0) {
status = usb_suspend_both(udev, PMSG_AUTO_SUSPEND);
}
}
@@ -1519,7 +1521,7 @@ void usb_autopm_put_interface(struct usb
status = usb_autopm_do_interface(intf, -1);
dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, intf->pm_usage_cnt);
+ __func__, status, atomic_read(&intf->pm_usage_cnt));
}
EXPORT_SYMBOL_GPL(usb_autopm_put_interface);
@@ -1547,10 +1549,10 @@ void usb_autopm_put_interface_async(stru
status = -ENODEV;
} else {
udev->last_busy = jiffies;
- --intf->pm_usage_cnt;
+ atomic_dec(&intf->pm_usage_cnt);
if (udev->autosuspend_disabled || udev->autosuspend_delay < 0)
status = -EPERM;
- else if (intf->pm_usage_cnt <= 0 &&
+ else if (atomic_read(&intf->pm_usage_cnt) <= 0 &&
!timer_pending(&udev->autosuspend.timer)) {
queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,
round_jiffies_up_relative(
@@ -1558,7 +1560,7 @@ void usb_autopm_put_interface_async(stru
}
}
dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, intf->pm_usage_cnt);
+ __func__, status, atomic_read(&intf->pm_usage_cnt));
}
EXPORT_SYMBOL_GPL(usb_autopm_put_interface_async);
@@ -1602,7 +1604,7 @@ int usb_autopm_get_interface(struct usb_
status = usb_autopm_do_interface(intf, 1);
dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, intf->pm_usage_cnt);
+ __func__, status, atomic_read(&intf->pm_usage_cnt));
return status;
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface);
@@ -1630,10 +1632,14 @@ int usb_autopm_get_interface_async(struc
status = -ENODEV;
else if (udev->autoresume_disabled)
status = -EPERM;
- else if (++intf->pm_usage_cnt > 0 && udev->state == USB_STATE_SUSPENDED)
- queue_work(ksuspend_usb_wq, &udev->autoresume);
+ else {
+ atomic_inc(&intf->pm_usage_cnt);
+ if (atomic_read(&intf->pm_usage_cnt) > 0 &&
+ udev->state == USB_STATE_SUSPENDED)
+ queue_work(ksuspend_usb_wq, &udev->autoresume);
+ }
dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, intf->pm_usage_cnt);
+ __func__, status, atomic_read(&intf->pm_usage_cnt));
return status;
}
EXPORT_SYMBOL_GPL(usb_autopm_get_interface_async);
@@ -1655,7 +1661,7 @@ int usb_autopm_set_interface(struct usb_
status = usb_autopm_do_interface(intf, 0);
dev_vdbg(&intf->dev, "%s: status %d cnt %d\n",
- __func__, status, intf->pm_usage_cnt);
+ __func__, status, atomic_read(&intf->pm_usage_cnt));
return status;
}
EXPORT_SYMBOL_GPL(usb_autopm_set_interface);
--
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