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[];
return NULL;
}
+/*
+ * This and enable_trace_probe/disable_trace_probe rely on event_mutex
+ * held by the caller, __ftrace_set_clr_event().
+ */
static int trace_probe_nr_files(struct trace_probe *tp)
{
- struct ftrace_event_file **file = tp->files;
+ struct ftrace_event_file **file = rcu_dereference_raw(tp->files);
int ret = 0;
if (file)
return ret;
}
-static DEFINE_MUTEX(probe_enable_lock);
-
/*
* Enable trace_probe
* if the file is NULL, enable "perf" handler, or enable "trace" handler.
{
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);
+ 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);
if (!new) {
ret = -ENOMEM;
- goto out_unlock;
+ goto out;
}
memcpy(new, old, n * sizeof(struct ftrace_event_file *));
new[n] = file;
} else
tp->flags |= TP_FLAG_PROFILE;
- if (trace_probe_is_enabled(tp) && trace_probe_is_registered(tp) &&
- !trace_probe_has_gone(tp)) {
+ if (trace_probe_is_registered(tp) && !trace_probe_has_gone(tp)) {
if (trace_probe_is_return(tp))
ret = enable_kretprobe(&tp->rp);
else
ret = enable_kprobe(&tp->rp.kp);
}
-
- out_unlock:
- mutex_unlock(&probe_enable_lock);
-
+ out:
return ret;
}
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;
}
{
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;
+ goto out;
}
if (n == 1) { /* Remove the last file */
GFP_KERNEL);
if (!new) {
ret = -ENOMEM;
- goto out_unlock;
+ goto out;
}
/* This copy & check loop copies the NULL stopper too */
else
disable_kprobe(&tp->rp.kp);
}
-
- out_unlock:
- mutex_unlock(&probe_enable_lock);
-
+ out:
return ret;
}
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)
{
int size, __size, dsize;
int rctx;
+ head = this_cpu_ptr(call->perf_events);
+ if (hlist_empty(head))
+ return;
+
dsize = __get_data_size(tp, regs);
__size = sizeof(*entry) + tp->size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
entry->ip = (unsigned long)tp->rp.kp.addr;
memset(&entry[1], 0, dsize);
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
-
- head = this_cpu_ptr(call->perf_events);
perf_trace_buf_submit(entry, size, rctx,
entry->ip, 1, regs, head, NULL);
}
int size, __size, dsize;
int rctx;
+ head = this_cpu_ptr(call->perf_events);
+ if (hlist_empty(head))
+ return;
+
dsize = __get_data_size(tp, regs);
__size = sizeof(*entry) + tp->size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
entry->func = (unsigned long)tp->rp.kp.addr;
entry->ret_ip = (unsigned long)ri->ret_addr;
store_trace_args(sizeof(*entry), tp, regs, (u8 *)&entry[1], dsize);
-
- head = this_cpu_ptr(call->perf_events);
perf_trace_buf_submit(entry, size, rctx,
entry->ret_ip, 1, regs, head, NULL);
}
#endif /* CONFIG_PERF_EVENTS */
+/*
+ * called by perf_trace_init() or __ftrace_set_clr_event() under event_mutex.
+ *
+ * kprobe_trace_self_tests_init() does enable_trace_probe/disable_trace_probe
+ * lockless, but we can't race with this __init function.
+ */
static __kprobes
int kprobe_register(struct ftrace_event_call *event,
enum trace_reg type, void *data)
return NULL;
}
+/*
+ * Nobody but us can call enable_trace_probe/disable_trace_probe at this
+ * stage, we can do this lockless.
+ */
static __init int kprobe_trace_self_tests_init(void)
{
int ret, warn = 0;
projects / linux-imx.git / blobdiff