Bug 18315

Summary: System hang when doing back-to-back captures from bt848/878 to file
Product: Base System Reporter: sch <sch>
Component: kernAssignee: freebsd-bugs (Nobody) <bugs>
Status: Closed FIXED    
Severity: Affects Only Me    
Priority: Normal    
Version: 4.0-RELEASE   
Hardware: Any   
OS: Any   

Description sch 2000-05-01 03:00:00 UTC
Short program causes system to lock-up completely ( no response to any 
keys, can't telnet to it, harddrive light doesn't go off even though 
there's no audible activity, num-lock key doesn't toggle its light).

The program just repeatedly captures an image and writes it to disk,
all in a SIGALRM handler.  If the spacing between the SIGALARM's is made
to be such that the disk writes run together (hard drive light on
continuously), the system locks solid after a few seconds.

This happened with release 3.3 also, I've never tried 3.4.
I have tried it on both a bt848 and a bt878 and have gotten lockups
on both (release 3.3 with bt848 and release 4.0 with bt878).

Note that just repeatedly capturing and reading the buffer 
(and not writing to file), or just repeatedly writing the capture
buffer to file (after only capturing once, initially), does not lead
to a hang.  You have to capture and write repeatedly (close together)
to get the hang.

How-To-Repeat: Assuming you have a bt848/bt878 installed:
Contact me at sch@aristotle.net and I'll send you "lockup.c",
(or tell me where I should have posted it!).
cc -o lockup lockup.c
(save any work and "sync")
./lockup &
wait for the hang
Comment 1 Mike Barcroft freebsd_committer freebsd_triage 2001-07-22 02:54:11 UTC
State Changed
From-To: open->feedback


Does this problem still occur in newer versions of FreeBSD, 
such as 4.3-RELEASE?
Comment 2 Mike Barcroft freebsd_committer freebsd_triage 2001-07-22 02:55:47 UTC
State Changed
From-To: feedback->closed


Superseded by PR: kern/18316