linux-kernel - [PATCH v6 01/11] printk: Avoid delaying messages that aren't solicited by any console

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Message-ID: <023621f3c477d6246e27d11b78ae28a2bcb47e8d.1730133890.git.chris@chrisdown.name>
Date: Mon, 28 Oct 2024 16:45:31 +0000
From: Chris Down <chris@...isdown.name>
To: Petr Mladek <pmladek@...e.com>
Cc: linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	John Ogness <john.ogness@...utronix.de>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Tony Lindgren <tony.lindgren@...ux.intel.com>, kernel-team@...com
Subject: [PATCH v6 01/11] printk: Avoid delaying messages that aren't
 solicited by any console

printk_delay() may introduce delays even when no console wants to emit
the message, which is unnecessary and may hold back messages we actually
care about. Add a check in printk_delay() to determine if any console
will print the message to avoid introducing unnecessary delays. This
change aligns with the existing behaviour of boot-delayed printk
messages, which already have a similar check.

Signed-off-by: Chris Down <chris@...isdown.name>
Reviewed-by: Petr Mladek <pmladek@...e.com>
---
 kernel/printk/printk.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index beb808f4c367..d6159f1c5b29 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1315,15 +1315,13 @@ static int __init boot_delay_setup(char *str)
 }
 early_param("boot_delay", boot_delay_setup);
 
-static void boot_delay_msec(int level)
+static void boot_delay_msec(void)
 {
 	unsigned long long k;
 	unsigned long timeout;
 
-	if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING)
-		|| suppress_message_printing(level)) {
+	if (boot_delay == 0 || system_state >= SYSTEM_RUNNING)
 		return;
-	}
 
 	k = (unsigned long long)loops_per_msec * boot_delay;
 
@@ -1342,7 +1340,7 @@ static void boot_delay_msec(int level)
 	}
 }
 #else
-static inline void boot_delay_msec(int level)
+static inline void boot_delay_msec(void)
 {
 }
 #endif
@@ -2124,7 +2122,10 @@ int printk_delay_msec __read_mostly;
 
 static inline void printk_delay(int level)
 {
-	boot_delay_msec(level);
+	if (suppress_message_printing(level))
+		return;
+
+	boot_delay_msec();
 
 	if (unlikely(printk_delay_msec)) {
 		int m = printk_delay_msec;
-- 
2.46.0