USB: make intf.pm_usage an atomic_t

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@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 1bad4e5..1c976c1 100644 (file)
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -235,7 +235,7 @@ static int usb_probe_interface(struct device *dev)
                /* 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 usb_driver *driver,
        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_device *udev, int reschedule)
                        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(struct usb_interface *intf,
                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_interface *intf)
 
        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(struct usb_interface *intf)
                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(struct usb_interface *intf)
                }
        }
        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_interface *intf)
 
        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(struct usb_interface *intf)
                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_interface *intf)
 
        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);

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index cb54420..69e3a96 100644 (file)
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -373,7 +373,7 @@ static void kick_khubd(struct usb_hub *hub)
        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 *hub, enum hub_activation_type type)
                                        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);

diff --git a/include/linux/usb.h b/include/linux/usb.h
index 3b45a0d..a34fa89 100644 (file)
--- a/include/linux/usb.h
+++ b/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_async(struct usb_interface *intf);
 
 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);
 }