Re: [Linux-usb-users] OHCI root_port_reset() deadly loop...

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From: Alan Stern
Date: Wednesday, October 17, 2007 - 8:56 am

On Tue, 16 Oct 2007, Greg KH wrote:


No, we do catch the one place where it happens.  The problem seems to
be that the hardware update takes some time.  That is, on one side we
take the write lock, talk to the EHCI hardware, and drop the write
lock.  On the other side we take the read lock, talk to the OHCI 
hardware, and drop the read lock.  Nevertheless, the interference 
occurs.  David B.'s interpretation is that the hardware's change of 
state takes more time than the CPU uses in manipulating locks and 
switching tasks.  Hence his suggestion for adding a delay.

Alan Stern

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Messages in current thread:
OHCI root_port_reset() deadly loop..., David Miller, (Sat Oct 6, 11:53 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Sun Oct 7, 12:31 am)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Sun Oct 7, 12:51 am)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 4:54 pm)
Re: OHCI root_port_reset() deadly loop..., Greg KH, (Mon Oct 8, 8:10 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 8:16 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Mon Oct 8, 8:34 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 8:42 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Mon Oct 8, 9:09 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Mon Oct 8, 9:36 pm)
Re: OHCI root_port_reset() deadly loop..., Greg KH, (Mon Oct 8, 9:39 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 9:44 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 9:47 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Mon Oct 8, 10:00 pm)
Re: OHCI root_port_reset() deadly loop..., Benjamin Herrenschmidt, (Mon Oct 8, 10:11 pm)
Re: OHCI root_port_reset() deadly loop..., Benjamin Herrenschmidt, (Mon Oct 8, 10:13 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 10:23 pm)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Mon Oct 8, 10:26 pm)
Re: OHCI root_port_reset() deadly loop..., Greg KH, (Mon Oct 8, 11:06 pm)
Re: OHCI root_port_reset() deadly loop..., Benjamin Herrenschmidt, (Mon Oct 8, 11:37 pm)
Re: OHCI root_port_reset() deadly loop..., Benjamin Herrenschmidt, (Mon Oct 8, 11:43 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Tue Oct 9, 9:38 am)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Tue Oct 9, 11:48 am)
Re: OHCI root_port_reset() deadly loop..., David Miller, (Tue Oct 9, 1:41 pm)
Re: OHCI root_port_reset() deadly loop..., Greg KH, (Tue Oct 9, 1:46 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Tue Oct 9, 2:05 pm)
Re: OHCI root_port_reset() deadly loop..., David Brownell, (Tue Oct 9, 2:09 pm)
Re: [Linux-usb-users] OHCI root_port_reset() deadly loop..., David Brownell, (Tue Oct 16, 11:26 am)
Re: [Linux-usb-users] OHCI root_port_reset() deadly loop..., Alan Stern, (Wed Oct 17, 8:56 am)