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Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/trace_kprobe.c47
1 files changed, 37 insertions, 10 deletions
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 636d45fe69b3..0a3d8d5c483d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -185,9 +185,14 @@ static struct trace_probe *find_trace_probe(const char *event,
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++;
@@ -209,9 +214,10 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
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);
@@ -251,11 +257,17 @@ enable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
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;
}
@@ -274,10 +286,11 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
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;
@@ -872,9 +885,16 @@ __kprobe_trace_func(struct trace_probe *tp, struct pt_regs *regs,
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++;
@@ -925,9 +945,16 @@ static __kprobes void
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++;
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