From: Rik van Riel Date: Wed, 27 May 2026 15:13:01 +0000 (-0400) Subject: perf/ftrace: Fix WARNING in __unregister_ftrace_function X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9581123304b23049437324038698af9fb56ee663;p=thirdparty%2Fkernel%2Flinux.git perf/ftrace: Fix WARNING in __unregister_ftrace_function perf_ftrace_function_unregister() unconditionally calls unregister_ftrace_function() without checking whether the ftrace_ops was ever successfully registered. This triggers a WARN_ON in __unregister_ftrace_function() when the ops doesn't have FTRACE_OPS_FL_ENABLED set. This can happen during perf_event_alloc() error cleanup when perf_trace_destroy() is called via __free_event() on an event whose ftrace_ops registration failed or was already torn down by perf_try_init_event()'s err_destroy path. The call path is: perf_event_alloc() error cleanup -> __free_event() -> event->destroy() [tp_perf_event_destroy] -> perf_trace_destroy() -> perf_trace_event_close() -> TRACE_REG_PERF_CLOSE -> perf_ftrace_function_unregister() -> unregister_ftrace_function() -> __unregister_ftrace_function() -> WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)) Fix this by checking FTRACE_OPS_FL_ENABLED before attempting to unregister. If the ops is not enabled, just free the filter and return success. Link: https://patch.msgid.link/20260527111301.2d0d8256@fangorn Signed-off-by: Rik van Riel Signed-off-by: Steven Rostedt --- diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c index a6bb7577e8c5..5b272856e5ab 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -497,7 +497,17 @@ static int perf_ftrace_function_register(struct perf_event *event) static int perf_ftrace_function_unregister(struct perf_event *event) { struct ftrace_ops *ops = &event->ftrace_ops; - int ret = unregister_ftrace_function(ops); + int ret = 0; + + /* + * Perf will call this unconditionally even if the ops is not + * enabled. The unregister_ftrace_function() will warn if called + * when not enabled. Just bypass the unregistering if ops isn't + * enabled here. + */ + if (ops->flags & FTRACE_OPS_FL_ENABLED) + ret = unregister_ftrace_function(ops); + ftrace_free_filter(ops); return ret; }