linux-kernel - [PATCH v4 4/4] printk: Give error on attempt to set log buffer length to over 4G

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Date:   Sat, 29 Sep 2018 22:48:49 +0800
From:   <zhe.he@...driver.com>
To:     <pmladek@...e.com>, <sergey.senozhatsky@...il.com>,
        <rostedt@...dmis.org>, <linux-kernel@...r.kernel.org>,
        <zhe.he@...driver.com>
Subject: [PATCH v4 4/4] printk: Give error on attempt to set log buffer length to over 4G

From: He Zhe <zhe.he@...driver.com>

Give explicit error for users who want to use larger log buffer.

Signed-off-by: He Zhe <zhe.he@...driver.com>
Cc: pmladek@...e.com
Cc: sergey.senozhatsky@...il.com
Cc: rostedt@...dmis.org
---
 kernel/printk/printk.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b84aac0..5ccfd5d 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1039,18 +1039,23 @@ void log_buf_vmcoreinfo_setup(void)
 static unsigned long __initdata new_log_buf_len;
 
 /* we practice scaling the ring buffer by powers of 2 */
-static void __init log_buf_len_update(unsigned size)
+static void __init log_buf_len_update(u64 size)
 {
+	if (size > UINT_MAX) {
+		size = UINT_MAX;
+		pr_err("log_buf over 4G is not supported.\n");
+	}
+
 	if (size)
 		size = roundup_pow_of_two(size);
 	if (size > log_buf_len)
-		new_log_buf_len = size;
+		new_log_buf_len = (unsigned long)size;
 }
 
 /* save requested log_buf_len since it's too early to process it */
 static int __init log_buf_len_setup(char *str)
 {
-	unsigned int size;
+	u64 size;
 
 	if (!str)
 		return -EINVAL;
-- 
2.7.4