[PATCH] printk: Give error on attempt to set log buffer length to over 2G

[He Zhe]

The current printk() is ready to handle log buffer size up to 2G.
Give an explicit error for users who want to use larger log buffer.

Also fix printk formatting to show the 2G as a positive number.

Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
---
 kernel/printk/printk.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 15f3e70be448..f595107ddf42 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1040,18 +1040,23 @@ 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 2G 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;
@@ -1121,7 +1126,7 @@ void __init setup_log_buf(int early)
 	}
 
 	if (unlikely(!new_log_buf)) {
-		pr_err("log_buf_len: %ld bytes not available\n",
+		pr_err("log_buf_len: %lu bytes not available\n",
 			new_log_buf_len);
 		return;
 	}
@@ -1134,8 +1139,8 @@ void __init setup_log_buf(int early)
 	memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
 	logbuf_unlock_irqrestore(flags);
 
-	pr_info("log_buf_len: %d bytes\n", log_buf_len);
-	pr_info("early log buf free: %d(%d%%)\n",
+	pr_info("log_buf_len: %u bytes\n", log_buf_len);
+	pr_info("early log buf free: %u(%u%%)\n",
 		free, (free * 100) / __LOG_BUF_LEN);
 }
 
-- 
2.13.7