From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
Dan Williams <dan.j.williams@intel.com>,
Ingo Molnar <mingo@redhat.com>, Jan Kara <jack@suse.cz>,
Matthew Wilcox <mawilcox@microsoft.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-nvdimm@ml01.01.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/6] dax: add tracepoint infrastructure, PMD tracing
Date: Fri, 25 Nov 2016 04:14:19 +0000 [thread overview]
Message-ID: <20161125041419.GT1555@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20161125024918.GX31101@dastard>
[Linus Cc'd]
On Fri, Nov 25, 2016 at 01:49:18PM +1100, Dave Chinner wrote:
> > they have become parts of stable userland ABI and are to be maintained
> > indefinitely. Don't expect "tracepoints are special case" to prevent that.
>
> I call bullshit just like I always do when someone spouts this
> "tracepoints are stable ABI" garbage.
> Quite frankly, anyone that wants to stop us from
> adding/removing/changing tracepoints or the code that they are
> reporting information about "because ABI" can go take a long walk
> off a short cliff. Diagnostic tracepoints are not part of the
> stable ABI. End of story.
Tell that to Linus. You had been in the room, IIRC, when that had been
brought up this year in Santa Fe. "End of story" is not going to be
yours (or mine, for that matter) to declare - Linus is the only one who
can do that. If he says "if userland code relies upon it, so that
userland code needs to be fixed" - I'm very happy (and everyone involved
can count upon quite a few free drinks from me at the next summit). If
it's "that userland code really shouldn't have relied upon it, and it's
real unfortunate that it does, but we still get to keep it working" -
too bad, "because ABI" is the reality and we will be the ones to take
that long walk.
What I heard from Linus sounded a lot closer to the second variant.
_IF_ I have misinterpreted that, I'd love to hear that. Linus?
PS: I'm dead serious about large amounts of booze of choice at LSFS 2017.
Bribery or shared celebration - call it whatever you like; I really,
really want to have tracepoints free from ABIfication concerns. They
certainly are useful for debugging purposes - no arguments here.
next prev parent reply other threads:[~2016-11-25 4:14 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-23 18:44 [PATCH 0/6] introduce DAX tracepoint support Ross Zwisler
2016-11-23 18:44 ` [PATCH 1/6] dax: fix build breakage with ext4, dax and !iomap Ross Zwisler
2016-11-24 9:02 ` Jan Kara
2016-11-28 19:15 ` Ross Zwisler
2016-11-29 8:53 ` Jan Kara
2016-11-30 19:04 ` Ross Zwisler
2016-12-01 7:53 ` Jan Kara
2016-11-23 18:44 ` [PATCH 2/6] dax: remove leading space from labels Ross Zwisler
2016-11-24 9:11 ` Jan Kara
2016-11-24 19:42 ` Dan Williams
2016-11-28 19:20 ` Ross Zwisler
2016-11-23 18:44 ` [PATCH 3/6] dax: add tracepoint infrastructure, PMD tracing Ross Zwisler
2016-11-24 9:16 ` Jan Kara
2016-11-24 17:32 ` Al Viro
2016-11-25 2:49 ` Dave Chinner
2016-11-25 4:14 ` Al Viro [this message]
2016-11-25 7:06 ` Dave Chinner
2016-11-25 7:37 ` Al Viro
2016-11-25 19:51 ` Linus Torvalds
2016-11-25 20:36 ` Mike Marshall
2016-11-25 21:48 ` Theodore Ts'o
2016-11-25 23:38 ` Linus Torvalds
2016-11-28 8:33 ` Jan Kara
2016-11-27 22:42 ` Dave Chinner
2016-11-28 0:58 ` Linus Torvalds
2016-11-28 1:45 ` Al Viro
2016-11-28 9:09 ` Dave Chinner
2016-11-25 3:00 ` Dave Chinner
2016-11-28 22:46 ` Ross Zwisler
2016-11-29 2:02 ` Dave Chinner
2017-03-08 22:05 ` Mike Marshall
2016-11-23 18:44 ` [PATCH 4/6] dax: update MAINTAINERS entries for FS DAX Ross Zwisler
2016-11-23 18:44 ` [PATCH 5/6] dax: add tracepoints to dax_pmd_load_hole() Ross Zwisler
2016-11-24 9:20 ` Jan Kara
2016-11-23 18:44 ` [PATCH 6/6] dax: add tracepoints to dax_pmd_insert_mapping() Ross Zwisler
2016-11-24 9:22 ` Jan Kara
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