tracing/uprobes: Add busy check when cleanup all uprobes

Add a busy check loop in cleanup_all_probes() before
trying to remove all events in uprobe_events, the same way
that kprobe_events does.

Without this change, writing null to uprobe_events will
try to remove events but if one of them is enabled, it will
stop there leaving some events cleared and others not clceared.

With this change, writing null to uprobe_events makes
sure all events are not enabled before removing events.
So, it clears all events, or returns an error (-EBUSY)
with keeping all events.

Link: http://lkml.kernel.org/r/154140841557.17322.12653952888762532401.stgit@devbox
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 31ea48eceda184ed5e807f9fe22394f831980982..b708e4ff7ea7817e73d70c3602a0ab76877da4e5 100644 (file)
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -587,12 +587,19 @@ static int cleanup_all_probes(void)
        int ret = 0;
 
        mutex_lock(&uprobe_lock);
+       /* Ensure no probe is in use. */
+       list_for_each_entry(tu, &uprobe_list, list)
+               if (trace_probe_is_enabled(&tu->tp)) {
+                       ret = -EBUSY;
+                       goto end;
+               }
        while (!list_empty(&uprobe_list)) {
                tu = list_entry(uprobe_list.next, struct trace_uprobe, list);
                ret = unregister_trace_uprobe(tu);
                if (ret)
                        break;
        }
+end:
        mutex_unlock(&uprobe_lock);
        return ret;
 }