linux-kernel - [PATCH -next] panic: complete the flush of the hard deadlock log messages to the serial port

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-next>] [day] [month] [year] [list]

Date:   Mon, 23 Nov 2020 13:13:59 +0000
From:   Xu Qiang <xuqiang36@...wei.com>
To:     <akpm@...ux-foundation.org>, <keescook@...omium.org>,
        <mingo@...nel.org>, <peterz@...radead.org>, <mcgrof@...nel.org>,
        <huyue2@...ong.com>, <yangtiezhu@...ngson.cn>, <will@...nel.org>,
        <aquini@...hat.com>, <gpiccoli@...onical.com>,
        <xuqiang36@...wei.com>, <aik@...abs.ru>,
        <linux-kernel@...r.kernel.org>
CC:     <rui.xiang@...wei.com>
Subject: [PATCH -next] panic: complete the flush of the hard deadlock log messages to the serial port

when hardlockup_all_cpu_backtrace is on, and there are
a large number of cores in the system, it takes
a long time to output the hard deadlock logs of all cores
to the serial port. When the console_flush_on_panic function
in panic is executed, console_locked is still held.
As a result, garbled characters are displayed in the serial port log.

To solve this problem, wait for a maximum of 10s for the serial port
to be released before console_flush_on_panic.

Signed-off-by: Xu Qiang <xuqiang36@...wei.com>
---
 kernel/panic.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/panic.c b/kernel/panic.c
index 332736a72a58..0014788e8141 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -301,6 +301,14 @@ void panic(const char *fmt, ...)
 	 * panic() is not being callled from OOPS.
 	 */
 	debug_locks_off();
+
+	/* Wait for all CPUs to complete console_unlock */
+	for (i = 0; i < 10 * 1000; i++) {
+		if (console_trylock())
+			break;
+		mdelay(1);
+	}
+
 	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
 
 	panic_print_sys_info();
-- 
2.25.0