From: Ingo Molnar <mingo@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] uprobes: Cleanup !CONFIG_UPROBES decls, unexport xol_area
Date: Mon, 11 Nov 2013 09:41:49 +0100 [thread overview]
Message-ID: <20131111084149.GC12405@gmail.com> (raw)
In-Reply-To: <20131109190344.GA32281@redhat.com>
* Oleg Nesterov <oleg@redhat.com> wrote:
> +++ b/kernel/events/uprobes.c
> @@ -86,6 +86,25 @@ struct return_instance {
> };
>
> /*
> + * On a breakpoint hit, thread contests for a slot. It frees the
> + * slot after singlestep. Currently a fixed number of slots are
> + * allocated.
> + */
> +struct xol_area {
So, my main complaint about the uprobes code isn't functional but
documentational, similar to what I outlined a few days ago: what this
comment does not explain is exactly what a 'XOL area' is.
You guys are changing code that reads like gobbledygook to people reading
it for the first time. It's understandable that you want to use
abbreviations and I don't object against that, but please explain key
concepts and data structures when they first come up - a very good place
to do that is in places where key structures are declared.
I didn't find any high level description of the XOL code, one which makes
clear that how we manage these out of line execution areas:
comet:~/tip> git grep -i 'out of line' $(find . -name '*uprobe*.[ch]')
arch/powerpc/kernel/uprobes.c: * arch_uprobe_pre_xol - prepare to execute out of line.
arch/x86/kernel/uprobes.c: * arch_uprobe_pre_xol - prepare to execute out of line.
arch/x86/kernel/uprobes.c: * address pushed by a call instruction executed out of line.
kernel/events/uprobes.c: * This area will be used for storing instructions for execution out of line.
kernel/events/uprobes.c:/* Prepare to single-step probed instruction out of line. */
The one that comes closest is:
* This area will be used for storing instructions for execution out of line.
... but that is a single sentence and deep inside the XOL code already.
Really, please make a better job of introducing other kernel hackers to
the code you are writing ...
Maybe even split the XOL code out into kernel/events/uprobes_xol.c or so?
That will give a natural place to explain yourselves at the beginning of
the file.
Thanks,
Ingo
next prev parent reply other threads:[~2013-11-11 8:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-09 19:03 [PATCH] uprobes: Cleanup !CONFIG_UPROBES decls, unexport xol_area Oleg Nesterov
2013-11-11 7:15 ` Srikar Dronamraju
2013-11-11 8:41 ` Ingo Molnar [this message]
2013-11-11 19:58 ` Oleg Nesterov
2013-11-11 21:03 ` Ingo Molnar
2013-11-19 16:25 ` [PATCH] uprobes: Document xol_area and arch_uprobe->insn/ixol Oleg Nesterov
2013-11-19 19:24 ` Ingo Molnar
2013-11-20 11:03 ` Srikar Dronamraju
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20131111084149.GC12405@gmail.com \
--to=mingo@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=oleg@redhat.com \
--cc=srikar@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).