[for-next][PATCH 0/2] tracing: Minor updates

[for-next][PATCH 0/2] tracing: Minor updates

[Steven Rostedt]

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This will be added to the queue for 3.10 and uploaded to my for-next
branch in my git repo.

Sahara (1):
      tracepoints: Prevent null probe from being added

Steven Rostedt (Red Hat) (1):
      tracing: Compare to 1 instead of zero for is_signed_type()

----
 include/linux/ftrace_event.h |    2 +-
 kernel/tracepoint.c          |   21 +++++++++++++--------
 2 files changed, 14 insertions(+), 9 deletions(-)

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[for-next][PATCH 1/2] tracing: Compare to 1 instead of zero for is_signed_type()

[Steven Rostedt]

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From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The formats of the trace events show if the type of a event field
is signed or not via a macro called is_signed_type(). This does
a trick with the type and compares a -1 to zero after typecasting
to the tested type. If it returns true, it's signed, otherwise
its not. But this unfortunately triggers a warning by gcc:

  warning: comparison of unsigned expression < 0 is always false

As we know it is always false (that's why we do it), this is a
false warning. Luckily for us, the comparison works with a 1 as
well, without giving the warning.

Convert the check to compare (type)-1 < (type)0 to (type)-1 < (type)1
to determine if the type is signed or not.

Link: http://lkml.kernel.org/r/CAErSpo4YXcY9fuOKWYGDkddJwk68kmZTohsmVB6QvrhjboOh1Q@mail.gmail.com

Reported-by: Bjorn Helgaas <bhelgaas@google.com>
Reported-by: Gary Hade <garyhade@us.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 include/linux/ftrace_event.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 4e28b01..34e00fb 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -333,7 +333,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
 extern int trace_add_event_call(struct ftrace_event_call *call);
 extern void trace_remove_event_call(struct ftrace_event_call *call);
 
-#define is_signed_type(type)	(((type)(-1)) < (type)0)
+#define is_signed_type(type)	(((type)(-1)) < (type)1)
 
 int trace_set_clr_event(const char *system, const char *event, int set);
 
-- 
1.7.10.4



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[for-next][PATCH 2/2] tracepoints: Prevent null probe from being added

[Steven Rostedt]

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From: Sahara <keun-o.park@windriver.com>

Somehow tracepoint_entry_add_probe() function allows a null probe function.
And, this may lead to unexpected results since the number of probe
functions in an entry can be counted by checking whether a probe is null
or not in the for-loop.
This patch prevents a null probe from being added.
In tracepoint_entry_remove_probe() function, checking probe parameter
within the for-loop is moved out for code efficiency, leaving the null probe
feature which removes all probe functions in the entry.

Link: http://lkml.kernel.org/r/1365991995-19445-1-git-send-email-kpark3469@gmail.com

Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Sahara <keun-o.park@windriver.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/tracepoint.c |   21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index d96ba22..99e7e31 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -112,7 +112,8 @@ tracepoint_entry_add_probe(struct tracepoint_entry *entry,
 	int nr_probes = 0;
 	struct tracepoint_func *old, *new;
 
-	WARN_ON(!probe);
+	if (WARN_ON(!probe))
+		return ERR_PTR(-EINVAL);
 
 	debug_print_probes(entry);
 	old = entry->funcs;
@@ -152,13 +153,18 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
 
 	debug_print_probes(entry);
 	/* (N -> M), (N > 1, M >= 0) probes */
-	for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
-		if (!probe ||
-		    (old[nr_probes].func == probe &&
-		     old[nr_probes].data == data))
-			nr_del++;
+	if (probe) {
+		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+			if (old[nr_probes].func == probe &&
+			     old[nr_probes].data == data)
+				nr_del++;
+		}
 	}
 
+	/*
+	 * If probe is NULL, then nr_probes = nr_del = 0, and then the
+	 * entire entry will be removed.
+	 */
 	if (nr_probes - nr_del == 0) {
 		/* N -> 0, (N > 1) */
 		entry->funcs = NULL;
@@ -173,8 +179,7 @@ tracepoint_entry_remove_probe(struct tracepoint_entry *entry,
 		if (new == NULL)
 			return ERR_PTR(-ENOMEM);
 		for (i = 0; old[i].func; i++)
-			if (probe &&
-			    (old[i].func != probe || old[i].data != data))
+			if (old[i].func != probe || old[i].data != data)
 				new[j++] = old[i];
 		new[nr_probes - nr_del].func = NULL;
 		entry->refcount = nr_probes - nr_del;
-- 
1.7.10.4



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