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Commit bd859281 authored by Alan Stern's avatar Alan Stern Committed by Greg Kroah-Hartman
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USB: create new workqueue thread for USB autosuspend 



This patch (as787) creates a new workqueue thread to handle delayed
USB autosuspend requests.  Previously the code used keventd.  However
it turns out that the hub driver's suspend routine calls
flush_scheduled_work(), making it a poor candidate for running in
keventd (the call immediately deadlocks).  The solution is to use a
new thread instead of keventd.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 6a9fb060

drivers/usb/core/driver.c

+6 −5
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 


#include <linux/device.h>

#include <linux/usb.h>

#include <linux/workqueue.h>

#include "hcd.h"

#include "usb.h"
@@ -1131,7 +1132,7 @@ void usb_autosuspend_device(struct usb_device *udev, int dec_usage_cnt) 
	mutex_lock_nested(&udev->pm_mutex, udev->level);

	udev->pm_usage_cnt -= dec_usage_cnt;

	if (udev->pm_usage_cnt <= 0)

		schedule_delayed_work(&udev->autosuspend,

		queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,

				USB_AUTOSUSPEND_DELAY);

	mutex_unlock(&udev->pm_mutex);

	// dev_dbg(&udev->dev, "%s: cnt %d\n",
@@ -1215,9 +1216,9 @@ void usb_autopm_put_interface(struct usb_interface *intf) 
	struct usb_device	*udev = interface_to_usbdev(intf);



	mutex_lock_nested(&udev->pm_mutex, udev->level);

	if (intf->condition != USB_INTERFACE_UNBOUND) {

		if (--intf->pm_usage_cnt <= 0)

			schedule_delayed_work(&udev->autosuspend,

	if (intf->condition != USB_INTERFACE_UNBOUND &&

			--intf->pm_usage_cnt <= 0) {

		queue_delayed_work(ksuspend_usb_wq, &udev->autosuspend,

				USB_AUTOSUSPEND_DELAY);

	}

	mutex_unlock(&udev->pm_mutex);

drivers/usb/core/usb.c

+39 −3
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <linux/smp_lock.h>

#include <linux/usb.h>

#include <linux/mutex.h>

#include <linux/workqueue.h>



#include <asm/io.h>

#include <asm/scatterlist.h>
@@ -47,6 +48,8 @@ const char *usbcore_name = "usbcore"; 


static int nousb;	/* Disable USB when built into kernel image */



struct workqueue_struct *ksuspend_usb_wq;	/* For autosuspend */





/**

 * usb_ifnum_to_if - get the interface object with a given interface number
@@ -170,9 +173,9 @@ static void usb_release_dev(struct device *dev) 


	udev = to_usb_device(dev);



#ifdef	CONFIG_PM

#ifdef	CONFIG_USB_SUSPEND

	cancel_delayed_work(&udev->autosuspend);

	flush_scheduled_work();

	flush_workqueue(ksuspend_usb_wq);

#endif

	usb_destroy_configuration(udev);

	usb_put_hcd(bus_to_hcd(udev->bus));
@@ -184,6 +187,28 @@ static void usb_release_dev(struct device *dev) 


#ifdef	CONFIG_PM



static int ksuspend_usb_init(void)

{

	ksuspend_usb_wq = create_singlethread_workqueue("ksuspend_usbd");

	if (!ksuspend_usb_wq)

		return -ENOMEM;

	return 0;

}



static void ksuspend_usb_cleanup(void)

{

	destroy_workqueue(ksuspend_usb_wq);

}



#else



#define ksuspend_usb_init()	0

#define ksuspend_usb_cleanup()	do {} while (0)



#endif



#ifdef	CONFIG_USB_SUSPEND



/* usb_autosuspend_work - callback routine to autosuspend a USB device */

static void usb_autosuspend_work(void *_udev)

{
@@ -195,6 +220,11 @@ static void usb_autosuspend_work(void *_udev) 
	mutex_unlock(&udev->pm_mutex);

}



#else



static void usb_autosuspend_work(void *_udev)

{}



#endif



/**
@@ -976,9 +1006,12 @@ static int __init usb_init(void) 
		return 0;

	}



	retval = bus_register(&usb_bus_type);

	retval = ksuspend_usb_init();

	if (retval)

		goto out;

	retval = bus_register(&usb_bus_type);

	if (retval) 

		goto bus_register_failed;

	retval = usb_host_init();

	if (retval)

		goto host_init_failed;
@@ -1014,6 +1047,8 @@ static int __init usb_init(void) 
	usb_host_cleanup();

host_init_failed:

	bus_unregister(&usb_bus_type);

bus_register_failed:

	ksuspend_usb_cleanup();

out:

	return retval;

}
@@ -1035,6 +1070,7 @@ static void __exit usb_exit(void) 
	usb_hub_cleanup();

	usb_host_cleanup();

	bus_unregister(&usb_bus_type);

	ksuspend_usb_cleanup();

}



subsys_initcall(usb_init);

drivers/usb/core/usb.h

+1 −0
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ extern int usb_autoresume_device(struct usb_device *udev, int inc_busy_cnt); 


#endif



extern struct workqueue_struct *ksuspend_usb_wq;

extern struct bus_type usb_bus_type;

extern struct usb_device_driver usb_generic_driver;