Merge tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty...

[linux-imx.git] / kernel / trace / trace_kprobe.c

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7ed6976493c87ec2d31637a60a285bc39b4925b8..243f6834d02675c9c1101e1eabe18e56eb7d3244 100644 (file)
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -95,7 +95,7 @@ static __kprobes bool trace_probe_is_on_module(struct trace_probe *tp)
 }
 
 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);
@@ -243,11 +243,11 @@ find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
 static int
 disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
 {
+       struct event_file_link *link = NULL;
+       int wait = 0;
        int ret = 0;
 
        if (file) {
-               struct event_file_link *link;
-
                link = find_event_file_link(tp, file);
                if (!link) {
                        ret = -EINVAL;
@@ -255,10 +255,7 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
                }
 
                list_del_rcu(&link->list);
-               /* synchronize with kprobe_trace_func/kretprobe_trace_func */
-               synchronize_sched();
-               kfree(link);
-
+               wait = 1;
                if (!list_empty(&tp->files))
                        goto out;
 
@@ -271,8 +268,22 @@ disable_trace_probe(struct trace_probe *tp, struct ftrace_event_file *file)
                        disable_kretprobe(&tp->rp);
                else
                        disable_kprobe(&tp->rp.kp);
+               wait = 1;
        }
  out:
+       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(link);    /* Ignored if link == NULL */
+       }
+
        return ret;
 }
 
@@ -340,9 +351,12 @@ static int unregister_trace_probe(struct trace_probe *tp)
        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;
 }
@@ -621,7 +635,9 @@ static int release_all_trace_probes(void)
        /* 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);
        }
 
@@ -1087,9 +1103,6 @@ kprobe_perf_func(struct trace_probe *tp, struct pt_regs *regs)
        __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
-       if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                    "profile buffer not large enough"))
-               return;
 
        entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
        if (!entry)
@@ -1120,9 +1133,6 @@ kretprobe_perf_func(struct trace_probe *tp, struct kretprobe_instance *ri,
        __size = sizeof(*entry) + tp->size + dsize;
        size = ALIGN(__size + sizeof(u32), sizeof(u64));
        size -= sizeof(u32);
-       if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
-                    "profile buffer not large enough"))
-               return;
 
        entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
        if (!entry)
@@ -1242,11 +1252,15 @@ static int register_probe_event(struct trace_probe *tp)
        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 */