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From:   Andrew Halaney <ahalaney@redhat.com>
To:     Jason Baron <jbaron@akamai.com>, Jim Cromie <jim.cromie@gmail.com>
Cc:     Andrew Halaney <ahalaney@redhat.com>, linux-kernel@vger.kernel.org
Subject: [PATCH v3 1/3] dyndbg: make dyndbg a known cli param
Date:   Mon, 20 Sep 2021 15:54:42 -0500
Message-Id: <20210920205444.20068-2-ahalaney@redhat.com>
In-Reply-To: <20210920205444.20068-1-ahalaney@redhat.com>
References: <20210920205444.20068-1-ahalaney@redhat.com>
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Right now dyndbg shows up as an unknown parameter if used on boot:

    Unknown command line parameters: dyndbg=+p

That's because it is unknown, it doesn't sit in the __param
section, so the processing done to warn users supplying an unknown
parameter doesn't think it is legitimate.

Install a dummy handler to register it. dynamic debug needs to search
the whole command line for modules listed that are currently builtin,
so there's no real work to be done in this callback.

Fixes: 86d1919a4fb0 ("init: print out unknown kernel parameters")
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
---
 lib/dynamic_debug.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index cb5abb42c16a..84c16309cc63 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -761,6 +761,18 @@ static __init int ddebug_setup_query(char *str)
 
 __setup("ddebug_query=", ddebug_setup_query);
 
+/*
+ * Install a noop handler to make dyndbg look like a normal kernel cli param.
+ * This avoids warnings about dyndbg being an unknown cli param when supplied
+ * by a user.
+ */
+static __init int dyndbg_setup(char *str)
+{
+	return 1;
+}
+
+__setup("dyndbg=", dyndbg_setup);
+
 /*
  * File_ops->write method for <debugfs>/dynamic_debug/control.  Gathers the
  * command text from userspace, parses and executes it.
-- 
2.31.1