linux-kernel - [PATCH v2] tty: Add comments for tty-ldisc module loading logic

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Date: Fri, 15 Dec 2023 21:41:30 +0800
From: Zijun Hu <quic_zijuhu@...cinc.com>
To: <gregkh@...uxfoundation.org>, <jirislaby@...nel.org>,
        <quic_qiancai@...cinc.com>, <quic_arandive@...cinc.com>,
        <quic_saipraka@...cinc.com>, <quic_vnivarth@...cinc.com>,
        <quic_eberman@...cinc.com>
CC: <quic_zijuhu@...cinc.com>, <linux-serial@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] tty: Add comments for tty-ldisc module loading logic

Current tty-ldisc module loading logic within tty_ldisc_get()
is prone to mislead beginner that the module is able to be loaded
by a user without capability CAP_SYS_MODULE, add comments to make
the logic easy to undertand.

Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.com>
---
Changes in v2:
- Remove condition checking changes

 drivers/tty/tty_ldisc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 3f68e213df1f..34526ffaccbc 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -150,6 +150,10 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 	 */
 	ldops = get_ldops(disc);
 	if (IS_ERR(ldops)) {
+		/*
+		 * Always request tty-ldisc module regardless of user's
+		 * CAP_SYS_MODULE if autoload is enabled.
+		 */
 		if (!capable(CAP_SYS_MODULE) && !tty_ldisc_autoload)
 			return ERR_PTR(-EPERM);
 		request_module("tty-ldisc-%d", disc);
-- 
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