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From: Ingo Molnar <mingo@elte.hu>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	Masami Hiramatsu <mhiramat@redhat.com>,
	Seiji Aguchi <saguchi@redhat.com>,
	linux-kernel@vger.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Subject: Re: [GIT PULL] tracing: make signal tracepoints more useful
Date: Wed, 18 Jan 2012 12:59:38 +0100	[thread overview]
Message-ID: <20120118115938.GA14863@elte.hu> (raw)
In-Reply-To: <20120117140408.GA10197@redhat.com>


* Oleg Nesterov <oleg@redhat.com> wrote:

> On 01/17, Ingo Molnar wrote:
> >
> > Any tool that requests the signal trace event, and copies 
> > the full (and now larger) record it got in the ring-buffer, 
> > without expanding the target record's size accordingly will 
> > *BREAK*.
> >
> > I do not claim that tools will break in practice - i'm 
> > raising the *possibility* out of caution and i'm frustrated 
> > that you *STILL* don't understand how ABIs are maintained in 
> > Linux.
> 
> OK, but what if we rename the tracepoint?
> 
> IOW, add the new tracepoint and remove the old one. Of course, 
> this can confuse the users of the current "signal_generate", 
> but this is safe. b413d48a does this...
> 
> Or this is not allowed too?

Everything is allowed that makes sense and does not break apps, 
with a strong preference towards the simplest possible variant.

I.e. your patch.

Thanks,

	Ingo

  reply	other threads:[~2012-01-18 11:59 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-10 17:45 [PATCH 0/2] tracing: make signal tracepoints more useful Oleg Nesterov
2012-01-10 17:45 ` [PATCH 1/2] tracing: let trace_signal_generate() report more info, kill overflow_fail/lose_info Oleg Nesterov
2012-01-10 17:45 ` [PATCH 2/2] tracing: send_sigqueue() needs trace_signal_generate() too Oleg Nesterov
2012-01-10 18:59 ` [PATCH 0/2] tracing: make signal tracepoints more useful Steven Rostedt
2012-01-10 21:09 ` Seiji Aguchi
2012-01-13 18:20 ` [GIT PULL] " Oleg Nesterov
2012-01-15 18:24   ` Oleg Nesterov
2012-01-16  7:45     ` Ingo Molnar
2012-01-16 12:31       ` Steven Rostedt
2012-01-16 12:53         ` Ingo Molnar
2012-01-16 15:10           ` Oleg Nesterov
2012-01-17 18:50             ` Linus Torvalds
2012-01-18  9:39               ` Ingo Molnar
2012-01-16 15:52           ` Steven Rostedt
2012-01-17 10:02             ` Ingo Molnar
2012-01-17 12:03               ` Steven Rostedt
2012-01-17 12:40                 ` Ingo Molnar
2012-01-17 14:04                   ` Oleg Nesterov
2012-01-18 11:59                     ` Ingo Molnar [this message]
2012-01-17 14:37                   ` Steven Rostedt
2012-01-17 14:55                     ` Oleg Nesterov
2012-01-20 18:01                     ` Jason Baron
2012-01-17 19:52               ` Steven Rostedt
2012-01-16 15:03       ` Oleg Nesterov
2012-01-16 15:42         ` Seiji Aguchi
2012-01-16 15:58         ` Steven Rostedt
2012-01-26 10:10   ` Ingo Molnar

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