Merge branch 'printk-rework' into for-linus

[sfrench/cifs-2.6.git] / kernel / printk / printk.c

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ffdd0dc7ec6df809101f3a618cb3a65e31e434d9..6639a0cfe0aca6591a1934fbaef32efc2da788d3 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1291,11 +1291,16 @@ static size_t info_print_prefix(const struct printk_info  *info, bool syslog,
  * done:
  *
  *   - Add prefix for each line.
+ *   - Drop truncated lines that no longer fit into the buffer.
  *   - Add the trailing newline that has been removed in vprintk_store().
- *   - Drop truncated lines that do not longer fit into the buffer.
+ *   - Add a string terminator.
+ *
+ * Since the produced string is always terminated, the maximum possible
+ * return value is @r->text_buf_size - 1;
  *
  * Return: The length of the updated/prepared text, including the added
- * prefixes and the newline. The dropped line(s) are not counted.
+ * prefixes and the newline. The terminator is not counted. The dropped
+ * line(s) are not counted.
  */
 static size_t record_print_text(struct printk_record *r, bool syslog,
                                bool time)
@@ -1338,26 +1343,31 @@ static size_t record_print_text(struct printk_record *r, bool syslog,
 
                /*
                 * Truncate the text if there is not enough space to add the
-                * prefix and a trailing newline.
+                * prefix and a trailing newline and a terminator.
                 */
-               if (len + prefix_len + text_len + 1 > buf_size) {
+               if (len + prefix_len + text_len + 1 + 1 > buf_size) {
                        /* Drop even the current line if no space. */
-                       if (len + prefix_len + line_len + 1 > buf_size)
+                       if (len + prefix_len + line_len + 1 + 1 > buf_size)
                                break;
 
-                       text_len = buf_size - len - prefix_len - 1;
+                       text_len = buf_size - len - prefix_len - 1 - 1;
                        truncated = true;
                }
 
                memmove(text + prefix_len, text, text_len);
                memcpy(text, prefix, prefix_len);
 
+               /*
+                * Increment the prepared length to include the text and
+                * prefix that were just moved+copied. Also increment for the
+                * newline at the end of this line. If this is the last line,
+                * there is no newline, but it will be added immediately below.
+                */
                len += prefix_len + line_len + 1;
-
                if (text_len == line_len) {
                        /*
-                        * Add the trailing newline removed in
-                        * vprintk_store().
+                        * This is the last line. Add the trailing newline
+                        * removed in vprintk_store().
                         */
                        text[prefix_len + line_len] = '\n';
                        break;
@@ -1382,6 +1392,14 @@ static size_t record_print_text(struct printk_record *r, bool syslog,
                text_len -= line_len + 1;
        }
 
+       /*
+        * If a buffer was provided, it will be terminated. Space for the
+        * string terminator is guaranteed to be available. The terminator is
+        * not counted in the return value.
+        */
+       if (buf_size > 0)
+               text[len] = 0;
+
        return len;
 }
 
@@ -3427,7 +3445,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
        while (prb_read_valid_info(prb, seq, &info, &line_count)) {
                if (r.info->seq >= dumper->next_seq)
                        break;
-               l += get_record_print_text_size(&info, line_count, true, time);
+               l += get_record_print_text_size(&info, line_count, syslog, time);
                seq = r.info->seq + 1;
        }
 
@@ -3437,7 +3455,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
                                                &info, &line_count)) {
                if (r.info->seq >= dumper->next_seq)
                        break;
-               l -= get_record_print_text_size(&info, line_count, true, time);
+               l -= get_record_print_text_size(&info, line_count, syslog, time);
                seq = r.info->seq + 1;
        }