linux-kernel - [PATCH 06/10] printk: Split delayed printing of warnings from vprintk

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Date:	Mon, 25 May 2015 14:46:29 +0200
From:	Petr Mladek <pmladek@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Dave Anderson <anderson@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Kay Sievers <kay@...y.org>, Jiri Kosina <jkosina@...e.cz>,
	Michal Hocko <mhocko@...e.cz>, Jan Kara <jack@...e.cz>,
	linux-kernel@...r.kernel.org, Wang Long <long.wanglong@...wei.com>,
	peifeiyue@...wei.com, dzickus@...hat.com, morgan.wang@...wei.com,
	sasha.levin@...cle.com, Petr Mladek <pmladek@...e.cz>
Subject: [PATCH 06/10] printk: Split delayed printing of warnings from vprintk_emit()

printk_emit() is too long. Let's split the delayed printing of warnings
into a separate function.

This patch just shuffles the code. There is no change in the functionality.

Signed-off-by: Petr Mladek <pmladek@...e.cz>
---
 kernel/printk/printk.c | 64 +++++++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8fb0aaaa6258..91b8043044ac 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -233,6 +233,9 @@ static DEFINE_RAW_SPINLOCK(logbuf_lock);
 DECLARE_WAIT_QUEUE_HEAD(log_wait);
 /* cpu currently holding logbuf_lock */
 static unsigned int logbuf_cpu = UINT_MAX;
+/* flags used for delayed printing of warnings */
+static int recursion_bug;
+static atomic_t nmi_message_lost;
 /* the next printk record to read by syslog(READ) or /proc/kmsg */
 static u64 syslog_seq;
 static u32 syslog_idx;
@@ -269,6 +272,8 @@ static u32 clear_idx;
 static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN);
 static char *log_buf = __log_buf;
 static u32 log_buf_len = __LOG_BUF_LEN;
+/* helper buffer to print formatted text */
+static char textbuf[LOG_LINE_MAX];
 
 /* Return log buffer address */
 char *log_buf_addr_get(void)
@@ -1701,13 +1706,44 @@ static int try_logbuf_lock_in_nmi(void)
 	return 0;
 }
 
+/*
+ * This function modifies the global textbuf and therefore it must be called
+ * under lockbuf_lock!
+ */
+static int vprintk_delayed_warnings(void)
+{
+	int printed_len = 0;
+	int text_len;
+
+	if (unlikely(recursion_bug)) {
+		static const char recursion_msg[] =
+			"BUG: recent printk recursion!";
+
+		recursion_bug = 0;
+		/* emit KERN_CRIT message */
+		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+					 NULL, 0, recursion_msg,
+					 strlen(recursion_msg));
+	}
+
+	if (unlikely(atomic_read(&nmi_message_lost))) {
+		int lost = atomic_xchg(&nmi_message_lost, 0);
+
+		text_len = scnprintf(textbuf, sizeof(textbuf),
+				     "BAD LUCK: lost %d message(s) from NMI context!",
+				     lost);
+		/* emit KERN_CRIT message */
+		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+					 NULL, 0, textbuf, text_len);
+	}
+
+	return printed_len;
+}
+
 asmlinkage int vprintk_emit(int facility, int level,
 			    const char *dict, size_t dictlen,
 			    const char *fmt, va_list args)
 {
-	static int recursion_bug;
-	static atomic_t nmi_message_lost;
-	static char textbuf[LOG_LINE_MAX];
 	char *text = textbuf;
 	size_t text_len = 0;
 	enum log_flags lflags = 0;
@@ -1770,27 +1806,7 @@ asmlinkage int vprintk_emit(int facility, int level,
 
 	logbuf_cpu = this_cpu;
 
-	if (unlikely(recursion_bug)) {
-		static const char recursion_msg[] =
-			"BUG: recent printk recursion!";
-
-		recursion_bug = 0;
-		/* emit KERN_CRIT message */
-		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
-					 NULL, 0, recursion_msg,
-					 strlen(recursion_msg));
-	}
-
-	if (unlikely(atomic_read(&nmi_message_lost))) {
-		int lost = atomic_xchg(&nmi_message_lost, 0);
-
-		text_len = scnprintf(text, sizeof(textbuf),
-				     "BAD LUCK: lost %d message(s) from NMI context!",
-				     lost);
-		/* emit KERN_CRIT message */
-		printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
-					 NULL, 0, text, text_len);
-	}
+	printed_len += vprintk_delayed_warnings();
 
 	/*
 	 * The printf needs to come first; we need the syslog
-- 
1.8.5.6

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