linux-kernel - [for-linus][PATCH 3/4] ftrace: Add cond_resched() to ftrace_graph_set

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Message-ID: <20250402022335.029884348@goodmis.org>
Date: Tue, 01 Apr 2025 22:23:11 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 stable@...r.kernel.org,
 zhoumin <teczm@...mail.com>
Subject: [for-linus][PATCH 3/4] ftrace: Add cond_resched() to ftrace_graph_set_hash()

From: zhoumin <teczm@...mail.com>

When the kernel contains a large number of functions that can be traced,
the loop in ftrace_graph_set_hash() may take a lot of time to execute.
This may trigger the softlockup watchdog.

Add cond_resched() within the loop to allow the kernel to remain
responsive even when processing a large number of functions.

This matches the cond_resched() that is used in other locations of the
code that iterates over all functions that can be traced.

Cc: stable@...r.kernel.org
Fixes: b9b0c831bed26 ("ftrace: Convert graph filter to use hash tables")
Link: https://lore.kernel.org/tencent_3E06CE338692017B5809534B9C5C03DA7705@qq.com
Signed-off-by: zhoumin <teczm@...mail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/ftrace.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 92015de6203d..1a48aedb5255 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6855,6 +6855,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer)
 				}
 			}
 		}
+		cond_resched();
 	} while_for_each_ftrace_rec();
 
 	return fail ? -EINVAL : 0;
-- 
2.47.2