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From: Breno Leitao <leitao@debian.org>
To: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>
Cc: thepacketgeek@gmail.com,
	Aijay Adams <aijay@meta.com>,
	netdev@vger.kernel.org (open list:NETWORKING DRIVERS),
	linux-kernel@vger.kernel.org (open list)
Subject: [PATCH net v2] netconsole: Do not shutdown dynamic configuration if cmdline is invalid
Date: Tue, 28 May 2024 01:42:24 -0700
Message-ID: <20240528084225.3215853-1-leitao@debian.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

If a user provides an invalid netconsole configuration during boot time
(e.g., specifying an invalid ethX interface), netconsole will be
entirely disabled. Consequently, the user won't be able to create new
entries in /sys/kernel/config/netconsole/ as that directory does not
exist.

Apart from misconfiguration, another issue arises when ethX is loaded as
a module and the netconsole= line in the command line points to ethX,
resulting in an obvious failure. This renders netconsole unusable, as
/sys/kernel/config/netconsole/ will never appear. This is more annoying
since users reconfigure (or just toggle) the configuratin later (see
commit 5fbd6cdbe304b ("netconsole: Attach cmdline target to dynamic
target"))

Create /sys/kernel/config/netconsole/ even if the command line arguments
are invalid, so, users can create dynamic entries in netconsole.

Reported-by: Aijay Adams <aijay@meta.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changelog:

v2:
 * Use IS_ENABLED(CONFIG_NETCONSOLE_DYNAMIC) directly instead of a
   external function to check if dynamic reconfiguration is enabled.

---
 drivers/net/netconsole.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index d7070dd4fe73..ab8a0623b1a1 100644
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -1262,6 +1262,8 @@ static int __init init_netconsole(void)
 		while ((target_config = strsep(&input, ";"))) {
 			nt = alloc_param_target(target_config, count);
 			if (IS_ERR(nt)) {
+				if (IS_ENABLED(CONFIG_NETCONSOLE_DYNAMIC))
+					continue;
 				err = PTR_ERR(nt);
 				goto fail;
 			}
-- 
2.43.0