Received-SPF: pass (google.com: domain of linux-kernel+bounces-187747-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Date: Thu, 23 May 2024 23:55:37 +0800 (CST)
Message-ID: <20240523235537910_yxfGMbTcSOmMkcfuK2d8@zte.com.cn>
Precedence: bulk
Mime-Version: 1.0
From: <xu.xin16@zte.com.cn>
To: <bigeasy@linutronix.de>, <john.ogness@linutronix.de>,
        <rostedt@goodmis.org>
Cc: <zhang.yunkai@zte.com.cn>, <yang.yang29@zte.com.cn>,
        <liu.chun2@zte.com.cn>, <si.hao@zte.com.cn>,
        <linux-kernel@vger.kernel.org>, <linux-rt-users@vger.kernel.org>,
        <rostedt@goodmis.org>, <xu.xin16@zte.com.cn>
Subject: =?UTF-8?B?W1BBVENIICA1LjEwLXJ0XSBwcmludGs6IGlnbm9yZSB0aGF0IGNvbnNvbGUgcHJlZW1wdGVkIGJ5IGlycS9zb2Z0aXJx?=
Content-Type: text/plain;
	charset="UTF-8"

From: xu xin <xu.xin16@zte.com.cn>

When we're in the unpreemptible context on the same cpu with which the
thread of console locates on, we should ignore this console for
pr_flush, because it's a vain and always lead to timeout until the console
thread get cpu resource.

Fixes: e65be5f4dc3ed("printk: Update John Ogness' printk series")
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Cc: Zhang Yunkai <zhang.yunkai@zte.com.cn>
---
kernel/printk/printk.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 7f27cfee283e..faab85dd4439 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3735,6 +3735,14 @@ bool pr_flush(int timeout_ms, bool reset_on_progress)
diff = 0;

for_each_console(con) {
+ /*
+ * When we're in the unpreemptible context on the same cpu
+ * with which the thread of console locates on, we should
+ * ignore this console, because it's a vain.
+ */
+ if (!preemptible() && con->thread &&
+ task_cpu(con->thread) == smp_processor_id())
+ continue;
if (!(con->flags & CON_ENABLED))
continue;
printk_seq = read_console_seq(con);
--
2.15.2