lkml.org 
[lkml]   [2006]   [Sep]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] Linux Kernel Markers 0.13 for 2.6.17
From
Date
Mathieu Desnoyers <compudj@krystal.dyndns.org> writes:

> [...]
> > Yep, that looks reasonable. Though you could just directly test a
> > per-marker enable flag, rather than using "condition"...
> [...]
> I am not sure I understand your suggestion correctly.. do you mean having
> a per-marker flag that would be loaded and tested at every marker site ?

I gather that one reason for working so hard with the inline assembly
is a race condition problem with the plain STAP_MARK style of marker
disconnection:

if (pointer) (*pointer)(args ...);

Granted, but this problem could almost certainly be dealt with simpler
than that. How about a compxchg or other atomic-fetch of the static
pointer with a local variable? That should solve the worry of an
(*NULL) call.

If we then become concerned with a valid pointer become obsolete (the
probe handler function wanting to unload), we might be able to use
some RCU-type deferral mechanism and/or preempt controls to ensure
that this does not happen.

- FChE
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-09-26 21:55    [W:0.130 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site