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Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint
- From: Ingo Molnar <mingo at elte dot hu>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- 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: Sat, 5 Dec 2009 08:16:35 +0100
- 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>
* 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.
> 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.
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?
I sense reluctance from the direction of Andrew and disinterest from the
VFS folks - not a good backdrop in general.
Ingo