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From: Alexey Dobriyan <adobriyan@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: ksummit-discuss@lists.linuxfoundation.org
Subject: Re: [Ksummit-discuss] [topic proposal] tracepoints and ABI stability warranties
Date: Wed, 7 Sep 2016 01:02:13 +0300	[thread overview]
Message-ID: <20160906220213.GA16979@p183.telecom.by> (raw)
In-Reply-To: <20160906213644.GA16732@p183.telecom.by>

On Wed, Sep 07, 2016 at 12:36:44AM +0300, Alexey Dobriyan wrote:
> P.S.: techically every kernel release almost certainly breaks crash(1)
> program, program many people on this list should be familiar with.
> It is unclear why rules should be different for tracepoints.

Concrete example:

	TRACE_EVENT(sched_switch,
        TP_STRUCT__entry(
                __array(        char,   prev_comm,      TASK_COMM_LEN   )
                __field(        pid_t,  prev_pid                        )
                __field(        int,    prev_prio                       )
                __field(        long,   prev_state
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

struct task_struct::state is long but it looks like a historical
artifact, it can be just int. In this case it is easy to extend value and
preserve compatibility.

  parent reply	other threads:[~2016-09-06 22:02 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-06 18:51 Al Viro
2016-09-06 19:22 ` Steven Rostedt
2016-09-06 21:36   ` Alexey Dobriyan
2016-09-06 21:53     ` Steven Rostedt
2016-09-06 22:41       ` Alexey Dobriyan
2016-09-06 23:12         ` Steven Rostedt
2016-09-08 11:43           ` Alexey Dobriyan
2016-09-07  5:10         ` Al Viro
2016-09-07  5:30           ` Andy Lutomirski
2016-09-07  6:41             ` Vlastimil Babka
2016-09-19 12:51               ` Michal Hocko
2016-09-07 13:15             ` Christian Borntraeger
2016-09-07 15:30             ` Shuah Khan
2016-09-07 16:10               ` Rik van Riel
2016-09-08  3:24                 ` Masami Hiramatsu
2016-09-15 19:23                 ` Mark Brown
2016-09-06 22:02     ` Alexey Dobriyan [this message]
2016-09-06 22:15       ` Steven Rostedt
2016-09-06 21:05 ` Shuah Khan
2016-09-08  3:13   ` Masami Hiramatsu
2016-09-07 23:17 ` Masami Hiramatsu

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