linux-kernel - [PATCH printk v4 12/39] um: kmsg_dumper: use srcu console list iterator

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20221114162932.141883-13-john.ogness@linutronix.de>
Date:   Mon, 14 Nov 2022 17:35:05 +0106
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Richard Weinberger <richard@....at>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Johannes Berg <johannes@...solutions.net>,
        linux-um@...ts.infradead.org
Subject: [PATCH printk v4 12/39] um: kmsg_dumper: use srcu console list iterator

Rather than using the console_lock to guarantee safe console list
traversal, use srcu console list iteration.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
Reviewed-by: Petr Mladek <pmladek@...e.com>
---
 arch/um/kernel/kmsg_dump.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 40abf1e9ccb1..427dd5a61a38 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -16,29 +16,26 @@ static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
 	struct console *con;
 	unsigned long flags;
 	size_t len = 0;
+	int cookie;
 
 	/*
 	 * If no consoles are available to output crash information, dump
 	 * the kmsg buffer to stdout.
 	 */
 
-	if (!console_trylock())
-		return;
-
-	for_each_console(con) {
+	cookie = console_srcu_read_lock();
+	for_each_console_srcu(con) {
 		/*
 		 * The ttynull console and disabled consoles are ignored
 		 * since they cannot output. All other consoles are
 		 * expected to output the crash information.
 		 */
 		if (strcmp(con->name, "ttynull") != 0 &&
-		    (con->flags & CON_ENABLED)) {
+		    (console_srcu_read_flags(con) & CON_ENABLED)) {
 			break;
 		}
 	}
-
-	console_unlock();
-
+	console_srcu_read_unlock(cookie);
 	if (con)
 		return;
 
-- 
2.30.2