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USB: create new workqueue thread for USB autosuspend

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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: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern
2006-09-19 10:14:07 -04:00
committed by Greg Kroah-Hartman
parent 6a9fb06039
commit bd859281c0
3 changed files with 46 additions and 8 deletions
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42
drivers/usb/core/usb.c
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@ -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 = ksuspend_usb_init();
if (retval)
goto out;
retval = bus_register(&usb_bus_type);
if (retval)
goto out;
goto bus_register_failed;
retval = usb_host_init();
if (retval)
goto host_init_failed;
@ -1014,6 +1047,8 @@ major_init_failed:
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);