Commit b96d0c59 authored by Shengming Hu's avatar Shengming Hu Committed by Steven Rostedt (Google)
Browse files

fgraph: Fix thresh_return nosleeptime double-adjust 

trace_graph_thresh_return() called handle_nosleeptime() and then delegated
to trace_graph_return(), which calls handle_nosleeptime() again. When
sleep-time accounting is disabled this double-adjusts calltime and can
produce bogus durations (including underflow).

Fix this by computing rettime once, applying handle_nosleeptime() only
once, using the adjusted calltime for threshold comparison, and writing
the return event directly via __trace_graph_return() when the threshold is
met.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260221113314048jE4VRwIyZEALiYByGK0My@zte.com.cn


Fixes: 3c9880f3 ("ftrace: Use a running sleeptime instead of saving on shadow stack")
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarShengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 6ca8379b

kernel/trace/trace_functions_graph.c

+10 −4
Original line number Diff line number Diff line
@@ -403,8 +403,12 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace, 
	unsigned long *task_var = fgraph_get_task_var(gops);

	struct fgraph_times *ftimes;

	struct trace_array *tr;

	unsigned int trace_ctx;

	u64 calltime, rettime;

	int size;



	rettime = trace_clock_local();



	ftrace_graph_addr_finish(gops, trace);



	if (*task_var & TRACE_GRAPH_NOTRACE) {
@@ -419,11 +423,13 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace, 
	tr = gops->private;

	handle_nosleeptime(tr, trace, ftimes, size);



	if (tracing_thresh &&

	    (trace_clock_local() - ftimes->calltime < tracing_thresh))

	calltime = ftimes->calltime;



	if (tracing_thresh && (rettime - calltime < tracing_thresh))

		return;

	else

		trace_graph_return(trace, gops, fregs);



	trace_ctx = tracing_gen_ctx();

	__trace_graph_return(tr, trace, trace_ctx, calltime, rettime);

}



static struct fgraph_ops funcgraph_ops = {