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fgraph: Fix thresh_return nosleeptime double-adjust

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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: 3c9880f3ab ("ftrace: Use a running sleeptime instead of saving on shadow stack")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Shengming Hu 2026-02-21 11:33:14 +08:00 • committed by Steven Rostedt (Google)
parent 6ca8379b5d
commit b96d0c59cd
1 changed files with 10 additions and 4 deletions
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14
kernel/trace/trace_functions_graph.c
View file

@ -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 = {