Revert "printk: remove unused code from kernel/printk.c"

This reverts commit acff181d3574244e651913df77332e897b88bff4.

1 files changed, 54 insertions, 0 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index b11cffec38fc..33d6dcdb4909 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -265,6 +265,60 @@ static inline void boot_delay_msec(void)
 }
 #endif
 
+/*
+ * Return the number of unread characters in the log buffer.
+ */
+static int log_buf_get_len(void)
+{
+	return logged_chars;
+}
+
+/*
+ * Copy a range of characters from the log buffer.
+ */
+int log_buf_copy(char *dest, int idx, int len)
+{
+	int ret, max;
+	bool took_lock = false;
+
+	if (!oops_in_progress) {
+		spin_lock_irq(&logbuf_lock);
+		took_lock = true;
+	}
+
+	max = log_buf_get_len();
+	if (idx < 0 || idx >= max) {
+		ret = -1;
+	} else {
+		if (len > max)
+			len = max;
+		ret = len;
+		idx += (log_end - max);
+		while (len-- > 0)
+			dest[len] = LOG_BUF(idx + len);
+	}
+
+	if (took_lock)
+		spin_unlock_irq(&logbuf_lock);
+
+	return ret;
+}
+
+/*
+ * Commands to do_syslog:
+ *
+ * 	0 -- Close the log.  Currently a NOP.
+ * 	1 -- Open the log. Currently a NOP.
+ * 	2 -- Read from the log.
+ * 	3 -- Read all messages remaining in the ring buffer.
+ * 	4 -- Read and clear all messages remaining in the ring buffer
+ * 	5 -- Clear ring buffer.
+ * 	6 -- Disable printk's to console
+ * 	7 -- Enable printk's to console
+ *	8 -- Set level of messages printed to console
+ *	9 -- Return number of unread characters in the log buffer
+ *     10 -- Return size of the log buffer
+ */
 int do_syslog(int type, char __user *buf, int len, bool from_file)
 {
 	unsigned i, j, limit, count;