const char *symbol; /* symbol name */
struct ftrace_event_class class;
struct ftrace_event_call call;
- struct ftrace_event_file **files;
+ struct ftrace_event_file * __rcu *files;
ssize_t size; /* trace entry size */
unsigned int nr_args;
struct probe_arg args[];
}
static int register_probe_event(struct trace_probe *tp);
-static void unregister_probe_event(struct trace_probe *tp);
+static int unregister_probe_event(struct trace_probe *tp);
static DEFINE_MUTEX(probe_lock);
static LIST_HEAD(probe_list);
static int trace_probe_nr_files(struct trace_probe *tp)
{
- struct ftrace_event_file **file = tp->files;
+ struct ftrace_event_file **file;
int ret = 0;
+ /*
+ * Since all tp->files updater is protected by probe_enable_lock,
+ * we don't need to lock an rcu_read_lock.
+ */
+ file = rcu_dereference_raw(tp->files);
if (file)
while (*(file++))
ret++;
mutex_lock(&probe_enable_lock);
if (file) {
- struct ftrace_event_file **new, **old = tp->files;
+ struct ftrace_event_file **new, **old;
int n = trace_probe_nr_files(tp);
+ old = rcu_dereference_raw(tp->files);
/* 1 is for new one and 1 is for stopper */
new = kzalloc((n + 2) * sizeof(struct ftrace_event_file *),
GFP_KERNEL);
static int
trace_probe_file_index(struct trace_probe *tp, struct ftrace_event_file *file)
{
+ struct ftrace_event_file **files;
int i;
- if (tp->files) {
- for (i = 0; tp->files[i]; i++)
- if (tp->files[i] == file)
+ /*
+ * Since all tp->files updater is protected by probe_enable_lock,
+ * we don't need to lock an rcu_read_lock.
+ */
+ files = rcu_dereference_raw(tp->files);
+ if (files) {
+ for (i = 0; files[i]; i++)
+ if (files[i] == file)
return i;
}
static int
disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
{
+ struct ftrace_event_file **old = NULL;
+ int wait = 0;
int ret = 0;
mutex_lock(&probe_enable_lock);
if (file) {
- struct ftrace_event_file **new, **old = tp->files;
+ struct ftrace_event_file **new, **old;
int n = trace_probe_nr_files(tp);
int i, j;
+ old = rcu_dereference_raw(tp->files);
if (n == 0 || trace_probe_file_index(tp, file) < 0) {
ret = -EINVAL;
goto out_unlock;
}
rcu_assign_pointer(tp->files, new);
-
- /* Make sure the probe is done with old files */
- synchronize_sched();
- kfree(old);
+ wait = 1;
} else
tp->flags &= ~TP_FLAG_PROFILE;
disable_kretprobe(&tp->rp);
else
disable_kprobe(&tp->rp.kp);
+ wait = 1;
}
out_unlock:
mutex_unlock(&probe_enable_lock);
+ if (wait) {
+ /*
+ * Synchronize with kprobe_trace_func/kretprobe_trace_func
+ * to ensure disabled (all running handlers are finished).
+ * This is not only for kfree(), but also the caller,
+ * trace_remove_event_call() supposes it for releasing
+ * event_call related objects, which will be accessed in
+ * the kprobe_trace_func/kretprobe_trace_func.
+ */
+ synchronize_sched();
+ kfree(old); /* Ignored if link == NULL */
+ }
+
return ret;
}
if (trace_probe_is_enabled(tp))
return -EBUSY;
+ /* Will fail if probe is being used by ftrace or perf */
+ if (unregister_probe_event(tp))
+ return -EBUSY;
+
__unregister_trace_probe(tp);
list_del(&tp->list);
- unregister_probe_event(tp);
return 0;
}
/* TODO: Use batch unregistration */
while (!list_empty(&probe_list)) {
tp = list_entry(probe_list.next, struct trace_probe, list);
- unregister_trace_probe(tp);
+ ret = unregister_trace_probe(tp);
+ if (ret)
+ goto end;
free_trace_probe(tp);
}
static __kprobes void
kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs)
{
- struct ftrace_event_file **file = tp->files;
+ /*
+ * Note: preempt is already disabled around the kprobe handler.
+ * However, we still need an smp_read_barrier_depends() corresponding
+ * to smp_wmb() in rcu_assign_pointer() to access the pointer.
+ */
+ struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
+
+ if (unlikely(!file))
+ return;
- /* Note: preempt is already disabled around the kprobe handler */
while (*file) {
__kprobe_trace_func(tp, regs, *file);
file++;
kretprobe_trace_func(struct trace_probe *tp, struct kretprobe_instance *ri,
struct pt_regs *regs)
{
- struct ftrace_event_file **file = tp->files;
+ /*
+ * Note: preempt is already disabled around the kprobe handler.
+ * However, we still need an smp_read_barrier_depends() corresponding
+ * to smp_wmb() in rcu_assign_pointer() to access the pointer.
+ */
+ struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
+
+ if (unlikely(!file))
+ return;
- /* Note: preempt is already disabled around the kprobe handler */
while (*file) {
__kretprobe_trace_func(tp, ri, regs, *file);
file++;
}
/* Event entry printers */
-enum print_line_t
+static enum print_line_t
print_kprobe_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
return TRACE_TYPE_PARTIAL_LINE;
}
-enum print_line_t
+static enum print_line_t
print_kretprobe_event(struct trace_iterator *iter, int flags,
struct trace_event *event)
{
return ret;
}
-static void unregister_probe_event(struct trace_probe *tp)
+static int unregister_probe_event(struct trace_probe *tp)
{
+ int ret;
+
/* tp->event is unregistered in trace_remove_event_call() */
- trace_remove_event_call(&tp->call);
- kfree(tp->call.print_fmt);
+ ret = trace_remove_event_call(&tp->call);
+ if (!ret)
+ kfree(tp->call.print_fmt);
+ return ret;
}
/* Make a debugfs interface for controlling probe points */
projects / GitHub / mt8127 / android_kernel_alcatel_ttab.git / blobdiff