re: kern/46648: disconnecting usb mouse crashes system

[matthew green <mrg%eterna.com.au@localhost>]

The following reply was made to PR kern/46648; it has been noted by GNATS.

From: matthew green <mrg%eterna.com.au@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost
Subject: re: kern/46648: disconnecting usb mouse crashes system
Date: Mon, 02 Jul 2012 09:02:49 +1000

 hmmmm, this problem looks pretty annoying, and might affect many
 devices.  the problem seems to be that:
 
        - device was pulled out with active transfers
 
        - the handling of an error in the transfer callback function
        is to call usbd_clear_endpoint_stall_async(), which then
        sends a clear endpoint transfer
 
        - adapter transfer list is empty, causing kmem_alloc call,
        triggering the assertion since this is happening from the
        softintr thread
 
 this idiom is used in many of the USB drivers, so a solution that
 does not require each one changing seems appropriate.
 
 i'm not sure yet exactly the right answer.  it's clear to me (and
 has been or a while, since before usbmp) that the USB softintr
 does way too much work.
 
 
 .mrg.