linux-kernel - Re: [PATCH] perf/scripts: tuple was set from long in both branches in python_process

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Date:	Thu, 25 Mar 2010 00:42:58 -0500
From:	Tom Zanussi <tzanussi@...il.com>
To:	Roel Kluin <roel.kluin@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/scripts: tuple was set from long in both branches
 in python_process_event()

Hi,

On Mon, 2010-03-22 at 18:22 +0100, Roel Kluin wrote:
> Regardless of the sign, the tuple was set from a long.
> 
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
>  .../util/scripting-engines/trace-event-python.c    |   13 ++++++++-----
>  1 files changed, 8 insertions(+), 5 deletions(-)
> 
> Was something like this intended?

Yeah, something like that - thanks for noticing it and providing the
patch.  After looking at the Python implementation, I modified your
patch as below...

Basically, Python wants to use a PyInt (which is internally a long) if
it can i.e. if the value will fit into that type.  If not, it stores it
into a PyLong, which isn't actually a long, but an arbitrary-precision
integer variable.

The code below is similar to to what Python does internally, and it
seems to work as expected on the x86 and x86_64 sytems I tested it on.

Thanks,

Tom

Signed-off-by: Tom Zanussi <tzanussi@...il.com>

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 33a414b..6a72f14 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -208,7 +208,7 @@ static void python_process_event(int cpu, void *data,
 				 int size __unused,
 				 unsigned long long nsecs, char *comm)
 {
-	PyObject *handler, *retval, *context, *t;
+	PyObject *handler, *retval, *context, *t, *obj;
 	static char handler_name[256];
 	struct format_field *field;
 	unsigned long long val;
@@ -256,16 +256,23 @@ static void python_process_event(int cpu, void *data,
 				offset &= 0xffff;
 			} else
 				offset = field->offset;
-			PyTuple_SetItem(t, n++,
-				PyString_FromString((char *)data + offset));
+			obj = PyString_FromString((char *)data + offset);
 		} else { /* FIELD_IS_NUMERIC */
 			val = read_size(data + field->offset, field->size);
 			if (field->flags & FIELD_IS_SIGNED) {
-				PyTuple_SetItem(t, n++, PyInt_FromLong(val));
+				if ((long long)val >= LONG_MIN &&
+				    (long long)val <= LONG_MAX)
+					obj = PyInt_FromLong(val);
+				else
+					obj = PyLong_FromLongLong(val);
 			} else {
-				PyTuple_SetItem(t, n++, PyInt_FromLong(val));
+				if (val <= LONG_MAX)
+					obj = PyInt_FromLong(val);
+				else
+					obj = PyLong_FromUnsignedLongLong(val);
 			}
 		}
+		PyTuple_SetItem(t, n++, obj);
 	}
 
 	if (_PyTuple_Resize(&t, n) == -1)




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