From: <hu.shengming@zte.com.cn>
To: <rostedt@goodmis.org>, <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>, <mathieu.desnoyers@efficios.com>,
<linux-kernel@vger.kernel.org>,
<linux-trace-kernel@vger.kernel.org>, <zhang.run@zte.com.cn>,
<yang.tao172@zte.com.cn>, <yang.yang29@zte.com.cn>
Subject: [PATCH RESEND] function_graph: restore direct mode when callbacks drop to one
Date: Fri, 13 Feb 2026 14:29:32 +0800 (CST) [thread overview]
Message-ID: <20260213142932519cuWSpEXeS4-UnCvNXnK2P@zte.com.cn> (raw)
From: Shengming Hu <hu.shengming@zte.com.cn>
When registering a second fgraph callback, direct path is disabled
and array loop is used instead.
When ftrace_graph_active falls back to one, we try to re-enable direct
mode via ftrace_graph_enable_direct(true, ...).
But ftrace_graph_enable_direct() incorrectly disables the static key
rather than enabling it.
This leaves fgraph_do_direct permanently off after first multi-callback
transition, so direct fast mode is never restored.
Fixes: cc60ee813b503 ("function_graph: Use static_call and branch to optimize entry function")
Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>
---
kernel/trace/fgraph.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index cc48d16be43e..4df766c690f9 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -1303,7 +1303,7 @@ static void ftrace_graph_enable_direct(bool enable_branch, struct fgraph_ops *go
static_call_update(fgraph_func, func);
static_call_update(fgraph_retfunc, retfunc);
if (enable_branch)
- static_branch_disable(&fgraph_do_direct);
+ static_branch_enable(&fgraph_do_direct);
}
static void ftrace_graph_disable_direct(bool disable_branch)
--
2.25.1
reply other threads:[~2026-02-13 6:29 UTC|newest]
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