linux-kernel - [PATCH 1/2] printk: Refactor processing of line severity tokens

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Message-ID: <20080413122342.31769.40091.stgit@marcab.local.tull.net>
Date:	Sun, 13 Apr 2008 22:26:54 +1000
From:	Nick Andrew <nick@...k-andrew.net>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	<linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>, joe@...ches.com
Subject: [PATCH 1/2] printk: Refactor processing of line severity tokens

printk: Refactor processing of line severity tokens

Restructure the logic of vprintk() so the processing of the leading
3 characters of each input line is in one place, regardless whether
printk_time is enabled. This makes the code smaller and easier to
understand.

Signed-off-by: Nick Andrew <nick@...k-andrew.net>
---
This is the third revision.

  rev 1 - initial patch, refactor + remember current_log_level
  rev 2 - split into 2 parts
  rev 3 - I realised that rev 2 is inefficient; all I had to do was move
          the declaration of current_log_level, to alter the memory
	  behaviour.

 kernel/printk.c |   61 ++++++++++++++++++++++++-------------------------------
 1 files changed, 27 insertions(+), 34 deletions(-)


diff --git a/kernel/printk.c b/kernel/printk.c
index c46a20a..02ca845 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -656,11 +656,11 @@ static int printk_recursion_bug;
 
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
-	static int log_level_unknown = 1;
+	static int new_text_line = 1;
 	static char printk_buf[1024];
 
-	unsigned long flags;
 	int printed_len = 0;
+	unsigned long flags;
 	int this_cpu;
 	char *p;
 
@@ -702,61 +702,54 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 	printed_len += vscnprintf(printk_buf + printed_len,
 				  sizeof(printk_buf) - printed_len, fmt, args);
 
+
 	/*
 	 * 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++) {
-		if (log_level_unknown) {
-                        /* log_level_unknown signals the start of a new line */
+		if (new_text_line) {
+			int current_log_level = default_message_loglevel;
+			/* 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');
+			emit_log_char('>');
+			printed_len += 3;
+			new_text_line = 0;
+
 			if (printk_time) {
-				int loglev_char;
+				/* Follow the token with the time */
 				char tbuf[50], *tp;
 				unsigned tlen;
 				unsigned long long t;
 				unsigned long nanosec_rem;
 
-				/*
-				 * force the log level token to be
-				 * before the time output.
-				 */
-				if (p[0] == '<' && p[1] >='0' &&
-				   p[1] <= '7' && p[2] == '>') {
-					loglev_char = p[1];
-					p += 3;
-					printed_len -= 3;
-				} else {
-					loglev_char = default_message_loglevel
-						+ '0';
-				}
 				t = cpu_clock(printk_cpu);
 				nanosec_rem = do_div(t, 1000000000);
-				tlen = sprintf(tbuf,
-						"<%c>[%5lu.%06lu] ",
-						loglev_char,
-						(unsigned long)t,
-						nanosec_rem/1000);
+				tlen = sprintf(tbuf, "[%5lu.%06lu] ",
+						(unsigned long) t,
+						nanosec_rem / 1000);
 
 				for (tp = tbuf; tp < tbuf + tlen; tp++)
 					emit_log_char(*tp);
 				printed_len += tlen;
-			} else {
-				if (p[0] != '<' || p[1] < '0' ||
-				   p[1] > '7' || p[2] != '>') {
-					emit_log_char('<');
-					emit_log_char(default_message_loglevel
-						+ '0');
-					emit_log_char('>');
-					printed_len += 3;
-				}
 			}
-			log_level_unknown = 0;
+
 			if (!*p)
 				break;
 		}
+
 		emit_log_char(*p);
 		if (*p == '\n')
-			log_level_unknown = 1;
+			new_text_line = 1;
 	}
 
 	/*

--
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