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tracing: add protection around module events unload

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When reading the trace buffer, there is a race that when a module
is unloaded it removes events that is stilled referenced in the buffers.
This patch adds the protection around the unloading of the events
from modules and the reading of the trace buffers.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2009-06-09 17:29:07 -04:00
committed by Steven Rostedt
parent 725c624a58
commit 110bf2b764
3 changed files with 19 additions and 4 deletions
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4
kernel/trace/trace_events.c
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@@ -1050,12 +1050,13 @@ static void trace_module_remove_events(struct module *mod)
struct ftrace_event_call *call, *p;
bool found = false;
down_write(&trace_event_mutex);
list_for_each_entry_safe(call, p, &ftrace_events, list) {
if (call->mod == mod) {
found = true;
ftrace_event_enable_disable(call, 0);
if (call->event)
unregister_ftrace_event(call->event);
__unregister_ftrace_event(call->event);
debugfs_remove_recursive(call->dir);
list_del(&call->list);
trace_destroy_fields(call);
@@ -1079,6 +1080,7 @@ static void trace_module_remove_events(struct module *mod)
*/
if (found)
tracing_reset_current_online_cpus();
up_write(&trace_event_mutex);
}
static int trace_module_notify(struct notifier_block *self,