linux-kernel - [PATCH 2/2] x86/e820: Use pr_debug to avoid spamming dmesg log with debug messages

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Date:   Mon, 3 May 2021 21:40:30 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Jason Baron <jbaron@...mai.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/2] x86/e820: Use pr_debug to avoid spamming dmesg log with
 debug messages

e820 emits quite some debug messages to the dmesg log. Let's restrict
this to cases where the debug output is actually requested. Switch to
pr_debug() for this purpose and make sure by checking the return code
that pr_cont() is only called if applicable.

Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
---
 arch/x86/kernel/e820.c | 27 ++++++++++++++++-----------
 1 file changed, 16 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index bc0657f0d..67ad4d8f0 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -465,6 +465,7 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
 	u64 end;
 	unsigned int i;
 	u64 real_updated_size = 0;
+	int printed;
 
 	BUG_ON(old_type == new_type);
 
@@ -472,11 +473,13 @@ __e820__range_update(struct e820_table *table, u64 start, u64 size, enum e820_ty
 		size = ULLONG_MAX - start;
 
 	end = start + size;
-	printk(KERN_DEBUG "e820: update [mem %#010Lx-%#010Lx] ", start, end - 1);
-	e820_print_type(old_type);
-	pr_cont(" ==> ");
-	e820_print_type(new_type);
-	pr_cont("\n");
+	printed = pr_debug("e820: update [mem %#010Lx-%#010Lx] ", start, end - 1);
+	if (printed > 0) {
+		e820_print_type(old_type);
+		pr_cont(" ==> ");
+		e820_print_type(new_type);
+		pr_cont("\n");
+	}
 
 	for (i = 0; i < table->nr_entries; i++) {
 		struct e820_entry *entry = &table->entries[i];
@@ -540,7 +543,7 @@ static u64 __init e820__range_update_kexec(u64 start, u64 size, enum e820_type o
 /* Remove a range of memory from the E820 table: */
 u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type)
 {
-	int i;
+	int printed, i;
 	u64 end;
 	u64 real_removed_size = 0;
 
@@ -548,10 +551,12 @@ u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool
 		size = ULLONG_MAX - start;
 
 	end = start + size;
-	printk(KERN_DEBUG "e820: remove [mem %#010Lx-%#010Lx] ", start, end - 1);
-	if (check_type)
-		e820_print_type(old_type);
-	pr_cont("\n");
+	printed = pr_debug("e820: remove [mem %#010Lx-%#010Lx] ", start, end - 1);
+	if (printed > 0) {
+		if (check_type)
+			e820_print_type(old_type);
+		pr_cont("\n");
+	}
 
 	for (i = 0; i < e820_table->nr_entries; i++) {
 		struct e820_entry *entry = &e820_table->entries[i];
@@ -1230,7 +1235,7 @@ void __init e820__reserve_resources_late(void)
 		if (start >= end)
 			continue;
 
-		printk(KERN_DEBUG "e820: reserve RAM buffer [mem %#010llx-%#010llx]\n", start, end);
+		pr_debug("e820: reserve RAM buffer [mem %#010llx-%#010llx]\n", start, end);
 		reserve_region_with_split(&iomem_resource, start, end, "RAM buffer");
 	}
 }
-- 
2.31.1