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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Douglas Anderson <dianders@chromium.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Sasha Levin <sashal@kernel.org>,
        kgdb-bugreport@lists.sourceforge.net
Subject: [PATCH AUTOSEL 5.4 31/80] kgdb: Make "kgdbcon" work properly with "kgdb_earlycon"
Date:   Mon, 26 Oct 2020 19:54:27 -0400
Message-Id: <20201026235516.1025100-31-sashal@kernel.org>
In-Reply-To: <20201026235516.1025100-1-sashal@kernel.org>
References: <20201026235516.1025100-1-sashal@kernel.org>
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From: Douglas Anderson <dianders@chromium.org>

[ Upstream commit b18b099e04f450cdc77bec72acefcde7042bd1f3 ]

On my system the kernel processes the "kgdb_earlycon" parameter before
the "kgdbcon" parameter.  When we setup "kgdb_earlycon" we'll end up
in kgdb_register_callbacks() and "kgdb_use_con" won't have been set
yet so we'll never get around to starting "kgdbcon".  Let's remedy
this by detecting that the IO module was already registered when
setting "kgdb_use_con" and registering the console then.

As part of this, to avoid pre-declaring things, move the handling of
the "kgdbcon" further down in the file.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200630151422.1.I4aa062751ff5e281f5116655c976dff545c09a46@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/debug/debug_core.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 2222f3225e53d..097ab02989f92 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -96,14 +96,6 @@ int dbg_switch_cpu;
 /* Use kdb or gdbserver mode */
 int dbg_kdb_mode = 1;
 
-static int __init opt_kgdb_con(char *str)
-{
-	kgdb_use_con = 1;
-	return 0;
-}
-
-early_param("kgdbcon", opt_kgdb_con);
-
 module_param(kgdb_use_con, int, 0644);
 module_param(kgdbreboot, int, 0644);
 
@@ -876,6 +868,20 @@ static struct console kgdbcons = {
 	.index		= -1,
 };
 
+static int __init opt_kgdb_con(char *str)
+{
+	kgdb_use_con = 1;
+
+	if (kgdb_io_module_registered && !kgdb_con_registered) {
+		register_console(&kgdbcons);
+		kgdb_con_registered = 1;
+	}
+
+	return 0;
+}
+
+early_param("kgdbcon", opt_kgdb_con);
+
 #ifdef CONFIG_MAGIC_SYSRQ
 static void sysrq_handle_dbg(int key)
 {
-- 
2.25.1