[PATCH] printk return value: fix it

What's the true meaning of the printk return value?  Should it include the
priority prefix length of 3?  and what about the timing information?  In
both cases it was broken:

strace -e write echo 1 > /dev/kmsg
=> write(1, "1\n", 2)                      = 5
strace -e write echo "<1>1" > /dev/kmsg
=> write(1, "<1>1\n", 5)                   = 8

The returned length was "length of input string + 3", I made it "length
of string output to the log buffer".

Note that I couldn't find any printk caller in the kernel interested by its
return value besides kmsg_write.

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Acked-By: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/printk.c b/kernel/printk.c
index 5287be83e3e7951740bfe4350dbc763f8d663981..2251be80cd22644bc82773ffb1cd59c6661dbc7e 100644 (file)
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -569,7 +569,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                                   p[1] <= '7' && p[2] == '>') {
                                        loglev_char = p[1];
                                        p += 3;
-                                       printed_len += 3;
+                                       printed_len -= 3;
                                } else {
                                        loglev_char = default_message_loglevel
                                                + '0';
@@ -584,7 +584,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 
                                for (tp = tbuf; tp < tbuf + tlen; tp++)
                                        emit_log_char(*tp);
-                               printed_len += tlen - 3;
+                               printed_len += tlen;
                        } else {
                                if (p[0] != '<' || p[1] < '0' ||
                                   p[1] > '7' || p[2] != '>') {
@@ -592,8 +592,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
                                        emit_log_char(default_message_loglevel
                                                + '0');
                                        emit_log_char('>');
+                                       printed_len += 3;
                                }
-                               printed_len += 3;
                        }
                        log_level_unknown = 0;
                        if (!*p)