linux-kernel - [PATCH_V2 1/2] fix the bug that printk can't support printk(KERN

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Message-ID: <1332725787.2359.27.camel@hebo>
Date:	Mon, 26 Mar 2012 09:36:27 +0800
From:	"he, bo" <bo.he@...el.com>
To:	Ingo Molnar <mingo@...nel.org>, akpm@...ux-foudation.org,
	mingo@...e.hu, rusty@...tcorp.com.au, a.p.zijlstra@...llo.nl,
	linux-kernel@...r.kernel.org, william.douglas@...el.com
Cc:	yanmin_zhang@...ux.intel.com
Subject: [PATCH_V2 1/2] fix the bug that printk can't support
 printk(KERN_LEVEL)

From: he bo <bo.he@...el.com>

Usually, there is a special scenario that developer wants to
call printk to just set up a log level (might be transferred
here as a parameter from upper level), then, later calling
of printk prints out real string with the same log level
continuously.

Current function vprintk has an issue to support this capability.
When the whole string in one calling to printk is just a log level,
it ignores it.

Signed-off-by: he, bo <bo.he@...el.com>
Reviewed-by: Zhang, Yanmin <yanmin.zhang@...el.com>
---
 kernel/printk.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/printk.c b/kernel/printk.c
index b663c2c..473afdb 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -909,7 +909,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 	 * Copy the output into log_buf. If the caller didn't provide
 	 * the appropriate log prefix, we insert them here
 	 */
-	for (; *p; p++) {
+	for (; plen || *p; p++) {
 		if (new_text_line) {
 			new_text_line = 0;
 
@@ -920,6 +920,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 				for (i = 0; i < plen; i++)
 					emit_log_char(printk_buf[i]);
 				printed_len += plen;
+				plen = 0;
 			} else {
 				/* Add log prefix */
 				emit_log_char('<');
@@ -946,10 +947,10 @@ asmlinkage int vprintk(const char *fmt, va_list args)
 				printed_len += tlen;
 			}
 
-			if (!*p)
-				break;
 		}
 
+		if (!*p)
+			break;
 		emit_log_char(*p);
 		if (*p == '\n')
 			new_text_line = 1;
-- 
1.7.1



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