printk: add generic functions to find KERN_<LEVEL> headers

The current form of a KERN_<LEVEL> is "<.>".

Add printk_get_level and printk_skip_level functions to handle these
formats.

These functions centralize tests of KERN_<LEVEL> so a future modification
can change the KERN_<LEVEL> style and shorten the number of bytes consumed
by these headers.

[akpm@linux-foundation.org: fix build error and warning]
Signed-off-by: Joe Perches <joe@perches.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Wu Fengguang <wfg@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 35 insertions, 5 deletions

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 1bec2f7a2d42..6e12e1f09047 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -24,6 +24,32 @@ extern const char linux_proc_banner[];
  */
 #define KERN_CONT       "<c>"
 
+static inline int printk_get_level(const char *buffer)
+{
+        if (buffer[0] == '<' && buffer[1] && buffer[2] == '>') {
+                switch (buffer[1]) {
+                case '0' ... '7':
+                case 'd':       /* KERN_DEFAULT */
+                case 'c':       /* KERN_CONT */
+                        return buffer[1];
+                }
+        }
+        return 0;
+}
+
+static inline const char *printk_skip_level(const char *buffer)
+{
+        if (printk_get_level(buffer)) {
+                switch (buffer[1]) {
+                case '0' ... '7':
+                case 'd':       /* KERN_DEFAULT */
+                case 'c':       /* KERN_CONT */
+                        return buffer + 3;
+                }
+        }
+        return buffer;
+}
+
 extern int console_printk[];
 
 #define console_loglevel (console_printk[0])
diff --git a/kernel/printk.c b/kernel/printk.c
index 852269adad25..0d882a2f231e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1487,6 +1487,7 @@ asmlinkage int vprintk_emit(int facility, int level,
         size_t text_len;
         enum log_flags lflags = 0;
         unsigned long flags;
+        int kern_level;
         int this_cpu;
         int printed_len = 0;
 
@@ -1543,17 +1544,20 @@ asmlinkage int vprintk_emit(int facility, int level,
         }
 
         /* strip syslog prefix and extract log level or control flags */
-        if (text[0] == '<' && text[1] && text[2] == '>') {
-                switch (text[1]) {
+        kern_level = printk_get_level(text);
+        if (kern_level) {
+                const char *end_of_header = printk_skip_level(text);
+                switch (kern_level) {
                 case '0' ... '7':
                         if (level == -1)
-                                level = text[1] - '0';
+                                level = kern_level - '0';
                 case 'd':       /* KERN_DEFAULT */
                         lflags |= LOG_PREFIX;
                 case 'c':       /* KERN_CONT */
-                        text += 3;
-                        text_len -= 3;
+                        break;
                 }
+                text_len -= end_of_header - text;
+                text = (char *)end_of_header;
         }
 
         if (level == -1)