printk: clean up handling of log-levels and newlines

It used to be that we would only look at the log-level in a printk()
after explicit newlines, which can cause annoying problems when the
previous printk() did not end with a '\n'. In that case, the log-level
marker would be just printed out in the middle of the line, and be
seen as just noise rather than change the logging level.

This changes things to always look at the log-level in the first
bytes of the printout. If a log level marker is found, it is always
used as the log-level. Additionally, if no newline existed, one is
added (unless the log-level is the explicit KERN_CONT marker, to
explicitly show that it's a continuation of a previous line).

Acked-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 883cd44ff765d9d90fdac42c11f51062bb8b8ef3..066bb1eddfea98c73fa644aba73726a1a4130b38 100644 (file)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -102,7 +102,7 @@ extern const char linux_proc_banner[];
  * line that had no enclosing \n). Only to be used by core/arch code
  * during early bootup (a continued line is not SMP-safe otherwise).
  */
-#define        KERN_CONT       ""
+#define        KERN_CONT       "<c>"
 
 extern int console_printk[];
 

diff --git a/kernel/printk.c b/kernel/printk.c
index 5052b5497c67995f57c6b548b0b52c1989f4027b..a87770ce73a2552c70025a982e941bb3853f0344 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -687,20 +687,33 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                                  sizeof(printk_buf) - printed_len, fmt, args);
 
 
+       p = printk_buf;
+
+       /* Do we have a loglevel in the string? */
+       if (p[0] == '<') {
+               unsigned char c = p[1];
+               if (c && p[2] == '>') {
+                       switch (c) {
+                       case '0' ... '7': /* loglevel */
+                               current_log_level = c - '0';
+                               if (!new_text_line) {
+                                       emit_log_char('\n');
+                                       new_text_line = 1;
+                               }
+                       /* Fallthrough - skip the loglevel */
+                       case 'c': /* KERN_CONT */
+                               p += 3;
+                               break;
+                       }
+               }
+       }
+
        /*
         * Copy the output into log_buf.  If the caller didn't provide
         * appropriate log level tags, we insert them here
         */
-       for (p = printk_buf; *p; p++) {
+       for ( ; *p; p++) {
                if (new_text_line) {
-                       /* If a token, set current_log_level and skip over */
-                       if (p[0] == '<' && p[1] >= '0' && p[1] <= '7' &&
-                           p[2] == '>') {
-                               current_log_level = p[1] - '0';
-                               p += 3;
-                               printed_len -= 3;
-                       }
-
                        /* Always output the token */
                        emit_log_char('<');
                        emit_log_char(current_log_level + '0');