[ltt-dev] [UST PATCH] Tracepoints: add noargs support

[ltt-dev] [UST PATCH] Tracepoints: add noargs support

[Mathieu Desnoyers]

Add support for tracepoints receiving no argument as parameters. Copied
from Linux kernel:

commit 38516ab59fbc5b3bb278cf5e1fe2867c70cff32e
Author: Steven Rostedt <srostedt at redhat.com>
Date:   Tue Apr 20 17:04:50 2010 -0400

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
CC: Nils Carlson <nils.carlson at ericsson.com>
CC: Steven Rostedt <srostedt at redhat.com>
---
 include/ust/tracepoint.h |   25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

Index: ust/include/ust/tracepoint.h
===================================================================
--- ust.orig/include/ust/tracepoint.h
+++ ust/include/ust/tracepoint.h
@@ -175,10 +175,27 @@ static inline void tracepoint_update_pro
 { }
 #endif /* CONFIG_TRACEPOINTS */
 
-#define DECLARE_TRACE(name, proto, args)			\
-	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
-			PARAMS(void *__data, proto),		\
-			PARAMS(__data, args))
+/*
+ * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
+ * (void). "void" is a special value in a function prototype and can
+ * not be combined with other arguments. Since the DECLARE_TRACE()
+ * macro adds a data element at the beginning of the prototype,
+ * we need a way to differentiate "(void *data, proto)" from
+ * "(void *data, void)". The second prototype is invalid.
+ *
+ * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
+ * and "void *__data" as the callback prototype.
+ *
+ * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
+ * "void *__data, proto" as the callback prototype.
+ */
+#define DECLARE_TRACE_NOARGS(name)					\
+		__DECLARE_TRACE(name, void, , void *__data, __data)
+
+#define DECLARE_TRACE(name, proto, args)				\
+		__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
+				PARAMS(void *__data, proto),		\
+				PARAMS(__data, args))
 
 /*
  * Connect a probe to a tracepoint.

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com

[ltt-dev] [UST PATCH] Tracepoints: add noargs support

[Nils Carlson]

Again, what do you think of UST_ prefixing the "externally visible" 
macros?

/Nils

On Mon, 11 Apr 2011, Mathieu Desnoyers wrote:

> Add support for tracepoints receiving no argument as parameters. Copied
> from Linux kernel:
>
> commit 38516ab59fbc5b3bb278cf5e1fe2867c70cff32e
> Author: Steven Rostedt <srostedt at redhat.com>
> Date:   Tue Apr 20 17:04:50 2010 -0400
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> CC: Nils Carlson <nils.carlson at ericsson.com>
> CC: Steven Rostedt <srostedt at redhat.com>
> ---
> include/ust/tracepoint.h |   25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> Index: ust/include/ust/tracepoint.h
> ===================================================================
> --- ust.orig/include/ust/tracepoint.h
> +++ ust/include/ust/tracepoint.h
> @@ -175,10 +175,27 @@ static inline void tracepoint_update_pro
> { }
> #endif /* CONFIG_TRACEPOINTS */
>
> -#define DECLARE_TRACE(name, proto, args)			\
> -	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
> -			PARAMS(void *__data, proto),		\
> -			PARAMS(__data, args))
> +/*
> + * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
> + * (void). "void" is a special value in a function prototype and can
> + * not be combined with other arguments. Since the DECLARE_TRACE()
> + * macro adds a data element at the beginning of the prototype,
> + * we need a way to differentiate "(void *data, proto)" from
> + * "(void *data, void)". The second prototype is invalid.
> + *
> + * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
> + * and "void *__data" as the callback prototype.
> + *
> + * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
> + * "void *__data, proto" as the callback prototype.
> + */
> +#define DECLARE_TRACE_NOARGS(name)					\
> +		__DECLARE_TRACE(name, void, , void *__data, __data)
> +
> +#define DECLARE_TRACE(name, proto, args)				\
> +		__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
> +				PARAMS(void *__data, proto),		\
> +				PARAMS(__data, args))
>
> /*
>  * Connect a probe to a tracepoint.
>
> -- 
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com
>

[ltt-dev] [UST PATCH] Tracepoints: add noargs support

[Mathieu Desnoyers]

* Nils Carlson (nils.carlson at ericsson.com) wrote:
> Again, what do you think of UST_ prefixing the "externally visible"  
> macros?

I plan to make tracepoints more widely adoped that just UST. So I would
go for e.g.:

tracepoint(name, args)
register_tracepoint(name, ...)
unregister_tracepoint(name, ...)

And about the integration with TRACE_EVENT, we could also start it soon,
but I would keep it as a separate step. I plan to come up with a
different name than "trace event" because ours will be slightly
different than the in-kernel incarnation, and I don't want to confuse
users.

Thanks,

Mathieu

>
> /Nils
>
> On Mon, 11 Apr 2011, Mathieu Desnoyers wrote:
>
>> Add support for tracepoints receiving no argument as parameters. Copied
>> from Linux kernel:
>>
>> commit 38516ab59fbc5b3bb278cf5e1fe2867c70cff32e
>> Author: Steven Rostedt <srostedt at redhat.com>
>> Date:   Tue Apr 20 17:04:50 2010 -0400
>>
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
>> CC: Nils Carlson <nils.carlson at ericsson.com>
>> CC: Steven Rostedt <srostedt at redhat.com>
>> ---
>> include/ust/tracepoint.h |   25 +++++++++++++++++++++----
>> 1 file changed, 21 insertions(+), 4 deletions(-)
>>
>> Index: ust/include/ust/tracepoint.h
>> ===================================================================
>> --- ust.orig/include/ust/tracepoint.h
>> +++ ust/include/ust/tracepoint.h
>> @@ -175,10 +175,27 @@ static inline void tracepoint_update_pro
>> { }
>> #endif /* CONFIG_TRACEPOINTS */
>>
>> -#define DECLARE_TRACE(name, proto, args)			\
>> -	__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
>> -			PARAMS(void *__data, proto),		\
>> -			PARAMS(__data, args))
>> +/*
>> + * The need for the DECLARE_TRACE_NOARGS() is to handle the prototype
>> + * (void). "void" is a special value in a function prototype and can
>> + * not be combined with other arguments. Since the DECLARE_TRACE()
>> + * macro adds a data element at the beginning of the prototype,
>> + * we need a way to differentiate "(void *data, proto)" from
>> + * "(void *data, void)". The second prototype is invalid.
>> + *
>> + * DECLARE_TRACE_NOARGS() passes "void" as the tracepoint prototype
>> + * and "void *__data" as the callback prototype.
>> + *
>> + * DECLARE_TRACE() passes "proto" as the tracepoint protoype and
>> + * "void *__data, proto" as the callback prototype.
>> + */
>> +#define DECLARE_TRACE_NOARGS(name)					\
>> +		__DECLARE_TRACE(name, void, , void *__data, __data)
>> +
>> +#define DECLARE_TRACE(name, proto, args)				\
>> +		__DECLARE_TRACE(name, PARAMS(proto), PARAMS(args),	\
>> +				PARAMS(void *__data, proto),		\
>> +				PARAMS(__data, args))
>>
>> /*
>>  * Connect a probe to a tracepoint.
>>
>> -- 
>> Mathieu Desnoyers
>> Operating System Efficiency R&D Consultant
>> EfficiOS Inc.
>> http://www.efficios.com
>>

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com