linux-kernel - [PATCH printk v2 10/18] printk: Provide helper for message prepending

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Message-Id: <20240603232453.33992-11-john.ogness@linutronix.de>
Date: Tue,  4 Jun 2024 01:30:45 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Petr Mladek <pmladek@...e.com>
Cc: Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: [PATCH printk v2 10/18] printk: Provide helper for message prepending

In order to support prepending different texts to printk
messages, split out the prepending code into a helper
function.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 kernel/printk/printk.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 4613f9145a8e..fcbf794a0aaf 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2806,30 +2806,25 @@ static void __console_unlock(void)
 #ifdef CONFIG_PRINTK
 
 /*
- * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This
- * is achieved by shifting the existing message over and inserting the dropped
- * message.
+ * Prepend the message in @pmsg->pbufs->outbuf with the message in
+ * @pmsg->pbufs->scratchbuf. This is achieved by shifting the existing message
+ * over and inserting the scratchbuf message.
  *
  * @pmsg is the printk message to prepend.
  *
- * @dropped is the dropped count to report in the dropped message.
+ * @len is the length of the message in @pmsg->pbufs->scratchbuf.
  *
  * If the message text in @pmsg->pbufs->outbuf does not have enough space for
- * the dropped message, the message text will be sufficiently truncated.
+ * the scratchbuf message, the message text will be sufficiently truncated.
  *
  * If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
  */
-void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
+static void __console_prepend_scratch(struct printk_message *pmsg, size_t len)
 {
 	struct printk_buffers *pbufs = pmsg->pbufs;
-	const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
 	const size_t outbuf_sz = sizeof(pbufs->outbuf);
 	char *scratchbuf = &pbufs->scratchbuf[0];
 	char *outbuf = &pbufs->outbuf[0];
-	size_t len;
-
-	len = scnprintf(scratchbuf, scratchbuf_sz,
-		       "** %lu printk messages dropped **\n", dropped);
 
 	/*
 	 * Make sure outbuf is sufficiently large before prepending.
@@ -2851,6 +2846,27 @@ void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
 	pmsg->outbuf_len += len;
 }
 
+/*
+ * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message".
+ * @pmsg->outbuf_len is updated appropriately.
+ *
+ * @pmsg is the printk message to prepend.
+ *
+ * @dropped is the dropped count to report in the dropped message.
+ */
+void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
+{
+	struct printk_buffers *pbufs = pmsg->pbufs;
+	const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
+	char *scratchbuf = &pbufs->scratchbuf[0];
+	size_t len;
+
+	len = scnprintf(scratchbuf, scratchbuf_sz,
+		       "** %lu printk messages dropped **\n", dropped);
+
+	__console_prepend_scratch(pmsg, len);
+}
+
 /*
  * Read and format the specified record (or a later record if the specified
  * record is not available).
-- 
2.39.2