@@ -59,6 +59,12 @@ struct tp_probes {
struct tracepoint_func probes[0];
};
+/* Called in removal of a func but failed to allocate a new tp_funcs */
+static void tp_stub_func(void)
+{
+ return;
+}
+
static inline void *allocate_probes(int count)
{
struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func)
@@ -97,6 +103,7 @@ func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
{
struct tracepoint_func *old, *new;
int nr_probes = 0;
+ int stub_funcs = 0;
int pos = -1;
if (WARN_ON(!tp_func->func))
@@ -113,14 +120,34 @@ func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
if (old[nr_probes].func == tp_func->func &&
old[nr_probes].data == tp_func->data)
return ERR_PTR(-EEXIST);
+ if (old[nr_probes].func == tp_stub_func)
+ stub_funcs++;
}
}
- /* + 2 : one for new probe, one for NULL func */
- new = allocate_probes(nr_probes + 2);
+ /* + 2 : one for new probe, one for NULL func - stub functions */
+ new = allocate_probes(nr_probes + 2 - stub_funcs);
if (new == NULL)
return ERR_PTR(-ENOMEM);
if (old) {
- if (pos < 0) {
+ if (stub_funcs) {
+ /* Need to copy one at a time to remove stubs */
+ int probes = 0;
+
+ pos = -1;
+ for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
+ if (old[nr_probes].func == tp_stub_func)
+ continue;
+ if (pos < 0 && old[nr_probes].prio < prio)
+ pos = probes++;
+ new[probes++] = old[nr_probes];
+ }
+ nr_probes = probes;
+ if (pos < 0)
+ pos = probes;
+ else
+ nr_probes--; /* Account for insertion */
+
+ } else if (pos < 0) {
pos = nr_probes;
memcpy(new, old, nr_probes * sizeof(struct tracepoint_func));
} else {
@@ -154,8 +181,9 @@ static void *func_remove(struct tracepoint_func **funcs,
/* (N -> M), (N > 1, M >= 0) probes */
if (tp_func->func) {
for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
- if (old[nr_probes].func == tp_func->func &&
- old[nr_probes].data == tp_func->data)
+ if ((old[nr_probes].func == tp_func->func &&
+ old[nr_probes].data == tp_func->data) ||
+ old[nr_probes].func == tp_stub_func)
nr_del++;
}
}
@@ -174,14 +202,32 @@ static void *func_remove(struct tracepoint_func **funcs,
/* N -> M, (N > 1, M > 0) */
/* + 1 for NULL */
new = allocate_probes(nr_probes - nr_del + 1);
- if (new == NULL)
- return ERR_PTR(-ENOMEM);
- for (i = 0; old[i].func; i++)
- if (old[i].func != tp_func->func
- || old[i].data != tp_func->data)
- new[j++] = old[i];
- new[nr_probes - nr_del].func = NULL;
- *funcs = new;
+ if (new) {
+ for (i = 0; old[i].func; i++)
+ if ((old[i].func != tp_func->func
+ || old[i].data != tp_func->data)
+ && old[i].func != tp_stub_func)
+ new[j++] = old[i];
+ new[nr_probes - nr_del].func = NULL;
+ *funcs = new;
+ } else {
+ /*
+ * Failed to allocate, replace the old function
+ * with calls to tp_stub_func.
+ */
+ for (i = 0; old[i].func; i++)
+ if (old[i].func == tp_func->func &&
+ old[i].data == tp_func->data) {
+ old[i].func = tp_stub_func;
+ /* Set the prio to the next event. */
+ if (old[i + 1].func)
+ old[i].prio =
+ old[i + 1].prio;
+ else
+ old[i].prio = -1;
+ }
+ *funcs = old;
+ }
}
debug_print_probes(*funcs);
return old;
@@ -234,10 +280,12 @@ static int tracepoint_remove_func(struct tracepoint *tp,
tp_funcs = rcu_dereference_protected(tp->funcs,
lockdep_is_held(&tracepoints_mutex));
old = func_remove(&tp_funcs, func);
- if (IS_ERR(old)) {
- WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM);
+ if (WARN_ON_ONCE(IS_ERR(old)))
return PTR_ERR(old);
- }
+
+ if (tp_funcs == old)
+ /* Failed allocating new tp_funcs, replaced func with stub */
+ return 0;
if (!tp_funcs) {
/* Removed last function */