From: Sahara <[email protected]>
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/[email protected]
Reviewed-by: Mathieu Desnoyers <[email protected]>
Acked-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Sahara <[email protected]>
Signed-off-by: Steven Rostedt <[email protected]>
---
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