This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>
- Cc: Andrew Morton <akpm at linux-foundation dot org>, lkml <linux-kernel at vger dot kernel dot org>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>, Oleg Nesterov <oleg at redhat dot com>, Roland McGrath <roland at redhat dot com>, Jason Baron <jbaron at redhat dot com>, KOSAKI Motohiro <kosaki dot motohiro at jp dot fujitsu dot com>
- Date: Mon, 07 Dec 2009 12:19:22 -0500
- Subject: Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint
- References: <4B128ECF.9020906@redhat.com> <20091202204637.25408.41195.stgit@dhcp-100-2-132.bos.redhat.com> <20091203103935.GA7628@elte.hu> <4B17A1CD.8060706@redhat.com> <20091205071635.GB25383@elte.hu>
Ingo Molnar wrote:
* Masami Hiramatsu<mhiramat@redhat.com> wrote:
Ingo Molnar wrote:
* Masami Hiramatsu<mhiramat@redhat.com> wrote:
Add signal coredump tracepoint which shows signal number, mm->flags,
limits, pointer to file structure and core file name.
Why is the kernel pointer to the file structure logged? User-space has
no use for it and the analysis value is low.
Ah, if open() or opening pipe fails, it becomes 0 or -ERRNO, so we can
check if there is an error.
ok, that wasnt obvious from the patch - worth adding it to the
changelog.
OK.
Perhaps, we can do below in trace_printk for trace users.
"open %s", (!file || IS_ERR((void *)file)) ? "failed" : "succeeded"
i'd rather suggest to pass an error code (and keep it 0 if none),
instead of some ad-hoc string message.
Sure. Or, perhaps, is it enough to show error code? (as block_rq_with_error did)
But ... the whole issue of VFS event logging and new tracepoints should
be approached from a more generic direction i think. Do we want to log
inode_nr:dev pairs as well? Shouldnt there be a generic event-class
definition via DECLARE_EVENT_CLASS for file related events, with 'core
dumped' just being a sub-event-code?
Hmm, would you mean that coredump event should be a VFS event? or
handling file open errors should be a VFS event?
There are many other special reasons of failing coredump, as I discussed
with Kosaki-san. So, I think coredump event should be different from VFS
events.
Of course, Failure of file opening event should be handled in VFS events
if possible. In that case, we just need to trace coredump event and
VFS open event, and matching file descriptor or something like that.
I sense reluctance from the direction of Andrew and disinterest from the
VFS folks - not a good backdrop in general.
Ingo
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com