Date: Mon, 5 Feb 2001 11:22:20 -0800 (PST) From: thomas.stratmann@ruhr-uni-bochum.de To: freebsd-gnats-submit@FreeBSD.org Subject: kern/24882: ktrace not syncing .out file before panic Message-ID: <200102051922.f15JMKx61176@freefall.freebsd.org>
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>Number: 24882 >Category: kern >Synopsis: ktrace not syncing .out file before panic >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Mon Feb 05 11:30:01 PST 2001 >Closed-Date: >Last-Modified: >Originator: Thomas Stratmann >Release: 4.2-Stable >Organization: >Environment: #0: Tue Jan 30 23:32:49 GMT 2001 root@byteslave:/usr/obj/usr/src/sys/KER1 i386 >Description: Tried to follow bug in mount which caused panic. Did ktrace on mount call -> empty ktrace.out (zero bytes) >How-To-Repeat: Call ktrace something, where something causes kernel panic. After reboot, look at ktrace.out inside last pwd >Fix: kernel tracing does not sync writing to .out-file. If VOP_FSync call is added inside ktrwrite function in kern_ktrace.c, it works well: I saw the actual kernel call which caused the panic as the last line output from kdump. Syncing must be done just before unflocking, of course. The line of code I added is out of reach for me now - anyway it probably is pretty useless as I lack kernel hacking experience and did not care deeply about the exact meanings of the arguments. As syncing is generally a speed vs. reliability tradeoff, it should be considered to introduce an option to ktrace which toggles syncing - if the manpage then is elaborate enough about the issue, even less experienced users will be able to give more precise error postings. btw the problem appeared on a 4.1-Stable I ran, but the part inside the ktrwrite function seemed unchanged to me when I looked at kern_ktrace.c on my 4.2-Stable box. This is my first posting here - would me delighted to get mail if anyone takes care about it to see for myself how useful this is. Thanx alot! >Release-Note: >Audit-Trail: >Unformatted: To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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