Messages in this thread |  | | | Date | Mon, 15 Jun 2009 11:24:28 -0400 | | From | Mathieu Desnoyers <> | | Subject | Re: [PATCH 3/7] add syscall tracepoints |
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* Jason Baron (jbaron@redhat.com) wrote: > On Fri, Jun 12, 2009 at 05:57:26PM -0400, Mathieu Desnoyers wrote: > > > Introduce a new 'DECLARE_TRACE_REG()' macro, so that tracepoints can associate > > > an external register/unregister function. > > > > > > > > > Signed-off-by: Jason Baron <jbaron@redhat.com> > > > > > > --- > > > include/linux/tracepoint.h | 27 +++++++++++++++++++++++---- > > > 1 files changed, 23 insertions(+), 4 deletions(-) > > > > > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > > > index 14df7e6..9a3660b 100644 > > > --- a/include/linux/tracepoint.h > > > +++ b/include/linux/tracepoint.h > > > @@ -61,7 +61,7 @@ struct tracepoint { > > > * not add unwanted padding between the beginning of the section and the > > > * structure. Force alignment to the same alignment as the section start. > > > */ > > > -#define DECLARE_TRACE(name, proto, args) \ > > > +#define DECLARE_TRACE_REG(name, proto, args, reg, unreg) \ > > > extern struct tracepoint __tracepoint_##name; \ > > > static inline void trace_##name(proto) \ > > > { \ > > > @@ -71,13 +71,29 @@ struct tracepoint { > > > } \ > > > static inline int register_trace_##name(void (*probe)(proto)) \ > > > { \ > > > - return tracepoint_probe_register(#name, (void *)probe); \ > > > + int ret; \ > > > + void (*func)(void) = (void (*)(void))reg; \ > > > + \ > > > + ret = tracepoint_probe_register(#name, (void *)probe); \ > > > + if (func && !ret) \ > > > + func(); \ > > > > I don't see why you need to add this weird interface when all you really > > need to do is to call the function to set the TIF flags explicitly in > > reg_event_syscall_enter when registering a tracepoint. > > > > Mathieu > > > > I could enable the TIF flag in reg_event_syscall_enter, however that > would not manage the TIF flag for other users of these traceoints. When > users 'register/unregister' with a tracepoint, they expect the tracepoint > to be enabled/disabled. If we move this functionality to the user, we are > changing how that interface works. Therefore, I associated the > enabling/disabling of the tracepoint, with the tracepoint definition. >
I agree it should be hidden from userspace APIs, but I don't think we should hide it or from the "in kernel" API users, really. People interfacing with this kind of API from the kernel-side expect to have a great level of control on how they use it, and we can expect people to know what they are doing.
Mathieu
> thanks, > > -Jason
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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