* Oleg Nesterov <o...@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
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