ftrace: Add cond_resched() to ftrace_graph_set_hash()

commit 42ea22e754ba4f2b86f8760ca27f6f71da2d982c upstream.

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@vger.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@foxmail.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 99fdeee3bcd87af48f2599af0c310fa007165079..580ceb75f8c389b36ce47f7a3722997a50196549 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6325,6 +6325,7 @@ ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer)
                                }
                        }
                }
+               cond_resched();
        } while_for_each_ftrace_rec();
 out:
        mutex_unlock(&ftrace_lock);