[PATCH] ACPICA: Add ACPI_MSG_DEBUG to set KERN_DEBUG for debug output

["Mario Limonciello (AMD)" <superm1@kernel.org>]

acpi_debug_print() emits ACPI debug output using multi-part
acpi_os_printf() and acpi_os_vprintf() calls without any loglevel
prefix.

When acpi_os_vprintf() processes a chunk without a loglevel prefix
(printk_get_level() returns 0), it prepends KERN_CONT. Because the initial
header chunk lacks a loglevel prefix, it either attaches to a preceding
unfinalized log message (inheriting its level) or, when split across
printk buffer records, falls back to the default message loglevel rather
than KERN_DEBUG. This can cause dmesg to misinterpret and colorize debug
messages as errors.

Define ACPI_MSG_DEBUG as KERN_DEBUG in aclinux.h (with an empty fallback
in acutils.h for ACPICA OS-independence) and prefix debug message headers
and context switch output in acpi_debug_print() with ACPI_MSG_DEBUG so
that printk records are properly tagged with KERN_DEBUG.

Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
Given this is purely for Linux - it's not obvious to me if it should
go upstream to ACPICA or directly to Linux.  Sending here for now.
---
 drivers/acpi/acpica/acutils.h   | 3 +++
 drivers/acpi/acpica/utdebug.c   | 4 ++--
 include/acpi/platform/aclinux.h | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/acpica/acutils.h b/drivers/acpi/acpica/acutils.h
index 9049bfee409c4..766a3080b5ea1 100644
--- a/drivers/acpi/acpica/acutils.h
+++ b/drivers/acpi/acpica/acutils.h
@@ -100,6 +100,9 @@ extern const char *acpi_gbl_clock_input_scale[];
 #ifndef ACPI_MSG_BIOS_WARNING
 #define ACPI_MSG_BIOS_WARNING   "Firmware Warning (ACPI): "
 #endif
+#ifndef ACPI_MSG_DEBUG
+#define ACPI_MSG_DEBUG          ""
+#endif
 
 /*
  * Common message suffix
diff --git a/drivers/acpi/acpica/utdebug.c b/drivers/acpi/acpica/utdebug.c
index a31e07400c34d..1f2cab491637f 100644
--- a/drivers/acpi/acpica/utdebug.c
+++ b/drivers/acpi/acpica/utdebug.c
@@ -156,7 +156,7 @@ acpi_debug_print(u32 requested_debug_level,
 	if (thread_id != acpi_gbl_previous_thread_id) {
 		if (ACPI_LV_THREADS & acpi_dbg_level) {
 			acpi_os_printf
-			    ("\n**** Context Switch from TID %u to TID %u ****\n\n",
+			    (ACPI_MSG_DEBUG "\n**** Context Switch from TID %u to TID %u ****\n\n",
 			     (u32)acpi_gbl_previous_thread_id, (u32)thread_id);
 		}
 
@@ -168,7 +168,7 @@ acpi_debug_print(u32 requested_debug_level,
 	 * Display the module name, current line number, thread ID (if requested),
 	 * current procedure nesting level, and the current procedure name
 	 */
-	acpi_os_printf("%9s-%04d ", module_name, line_number);
+	acpi_os_printf(ACPI_MSG_DEBUG "%9s-%04d ", module_name, line_number);
 
 #ifdef ACPI_APPLICATION
 	/*
diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
index 9b30bb9ed711c..5e2ed5e79d3b8 100644
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -169,6 +169,7 @@
 
 #define ACPI_MSG_BIOS_ERROR     KERN_ERR "ACPI BIOS Error (bug): "
 #define ACPI_MSG_BIOS_WARNING   KERN_WARNING "ACPI BIOS Warning (bug): "
+#define ACPI_MSG_DEBUG          KERN_DEBUG
 
 /*
  * Linux wants to use designated initializers for function pointer structs.
-- 
2.53.0