Re: kern/53788: vt switching panic

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR kern/53788; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost, 
	gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, dholland%NetBSD.org@localhost
Cc: 
Subject: Re: kern/53788: vt switching panic
Date: Sat, 15 Dec 2018 11:13:55 -0500

 On Dec 15, 11:50am, mlelstv%serpens.de@localhost (Michael van Elst) wrote:
 -- Subject: Re: kern/53788: vt switching panic
 
 |  The usl_syncdata structure is usually allocated by the program that
 |  tries to own the display and freed when it returns ownership after
 |  being sent a signal. Both operations are done by an ioctl in process
 |  context.
 |  
 |  But when the owner process has died and someone tries to switch
 |  the display with ctrl-alt-fX, the free operation is done by the
 |  keyboard interrupt handler.
 |  
 |  Usually you don't see this as the X server catches most signals,
 |  even segfaults, and tries to give back ownership before it exits.
 |  
 
 So why don't we use a linked list of sync cookies to free or kmem_intr_alloc/
 kmem_intr_free. This will always panic with DIAGNOSTIC when there is a timeout.
 
 christos