[PATCH v2 01/12] tracing/uprobes: Add busy check when cleanup all uprobes

From: Masami Hiramatsu
Date: Mon Nov 05 2018 - 04:00:40 EST


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

Without this change, writing null to uprobe_events will
try to remove events but if one of them is enabled, it
stopped there but some of events are already cleared.

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

Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
kernel/trace/trace_uprobe.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 31ea48eceda1..b708e4ff7ea7 100644
--- 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;
}