Re: 29-rc-mmotm - HID/USB wedge w/ WARNING: at kernel/workqueue.c:371

[Oliver Neukum <oliver@neukum.org>]

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Am Mittwoch 18 März 2009 04:26:42 schrieb Lai Jiangshan:> Andrew Morton wrote:> > On Wed, 18 Mar 2009 10:29:40 +0800 Lai Jiangshan <laijs@cn.fujitsu.com>> > wrote:> >> >> > static void run_workqueue(struct cpu_workqueue_struct *cwq)> > {> > 	spin_lock_irq(&cwq->lock);> > 	cwq->run_depth++;> > 	if (cwq->run_depth > 3) {> > 		/* morton gets to eat his hat */> > 		printk("%s: recursion depth exceeded: %d\n",> > 			__func__, cwq->run_depth);> > 		dump_stack();> > 	}> >> > That was added five or six years ago, and I never ever got to eat my hat.>> If Valdis.Kletnieks let lockdep work, he will see the complain> from lockdep at first.>> >> If it's hard for you avoid flush_scheduled_work() in> >> keventd's work fuction by other fix, you can create> >> another workqueue to handle your works, IMO.> >> > Why do we need to change anything here?  No known bugs were fixed, and> > some new ones were added.>> I prefer the code which has no known bugs and no known potential bugs.>> I defend myself:> I did not add a new bug as you said, it's the new code hid_cease_io()> adds a new unsafe usage of workqueue.
Very well, here's a patch.Please test.
	Regards		Oliverdiff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.cindex bc017cd..4306cb1 100644--- a/drivers/hid/usbhid/hid-core.c+++ b/drivers/hid/usbhid/hid-core.c@@ -1210,7 +1210,6 @@ static void hid_cease_io(struct usbhid_device *usbhid) 	usb_kill_urb(usbhid->urbin); 	usb_kill_urb(usbhid->urbctrl); 	usb_kill_urb(usbhid->urbout);-	flush_scheduled_work(); }  /* Treat USB reset pretty much the same as suspend/resume */@@ -1222,6 +1221,7 @@ static int hid_pre_reset(struct usb_interface *intf) 	spin_lock_irq(&usbhid->lock); 	set_bit(HID_RESET_PENDING, &usbhid->iofl); 	spin_unlock_irq(&usbhid->lock);+	cancel_work_sync(&usbhid->restart_work); 	hid_cease_io(usbhid);  	return 0;\0ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥