Re: [PATCH v2] [RFC] tracepoint: Add signal coredump tracepoint

[Ingo Molnar]

* Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Ingo Molnar wrote:
> > 
> > * Masami Hiramatsu <mhiramat@xxxxxxxxxx> 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
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