linux-kernel - Re: [PATCH v2] x86: use pr_cont() in dump

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Message-ID: <1504205513.2786.43.camel@perches.com>
Date:   Thu, 31 Aug 2017 11:51:53 -0700
From:   Joe Perches <joe@...ches.com>
To:     Jan Beulich <JBeulich@...e.com>, mingo@...e.hu, tglx@...utronix.de,
        hpa@...or.com
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86: use pr_cont() in dump_pagetable()

On Thu, 2017-08-31 at 01:30 -0600, Jan Beulich wrote:
> The lack of newlines in preceding format strings is a clear indication
> that these were meant to be continuations of one another, and indeed
> output ends up quite a bit more compact (and readable) that way.
> 
> Switch other plain printk()-s in the function instances to pr_info(),
> as requested.

I think this is incorrect as the functions immediately
preceding this dump_pagetable emit at KERN_ALERT and
the pr_info("BAD") use pr_info incorrectly.

I believe the appropriate conversion is:
---
>From f8127e18e0a466dd9a1393a4964eb9297cf39cb2 Mon Sep 17 00:00:00 2001
Message-Id: <f8127e18e0a466dd9a1393a4964eb9297cf39cb2.1504205373.git.joe@...ches.com>
From: Joe Perches <joe@...ches.com>
Date: Thu, 31 Aug 2017 11:48:02 -0700
Subject: [PATCH] x86: mm: fault: Use appropriate printk KERN_<level> output

printks without KERN_CONT are emitted on separate lines.

Emit the first line at KERN_ALERT and the continuations
at KERN_CONT as necessary.

Signed-off-by: Joe Perches <joe@...ches.com>
---
 arch/x86/mm/fault.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 2a1fa10c6a98..4b6125ed216e 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -396,14 +396,18 @@ static void dump_pagetable(unsigned long address)
 	pte_t *pte;
 
 #ifdef CONFIG_X86_PAE
-	printk("*pdpt = %016Lx ", pgd_val(*pgd));
+	printk(KERN_ALERT "*pdpt = %016Lx ", pgd_val(*pgd));
 	if (!low_pfn(pgd_val(*pgd) >> PAGE_SHIFT) || !pgd_present(*pgd))
 		goto out;
 #endif
 	p4d = p4d_offset(pgd, address);
 	pud = pud_offset(p4d, address);
 	pmd = pmd_offset(pud, address);
+#ifdef CONFIG_X86_PAE
 	printk(KERN_CONT "*pde = %0*Lx ", sizeof(*pmd) * 2, (u64)pmd_val(*pmd));
+#else
+	printk(KERN_ALERT "*pde = %0*Lx ", sizeof(*pmd) * 2, (u64)pmd_val(*pmd));
+#endif
 
 	/*
 	 * We must not directly access the pte in the highpte
@@ -415,9 +419,9 @@ static void dump_pagetable(unsigned long address)
 		goto out;
 
 	pte = pte_offset_kernel(pmd, address);
-	printk("*pte = %0*Lx ", sizeof(*pte) * 2, (u64)pte_val(*pte));
+	printk(KERN_CONT "*pte = %0*Lx ", sizeof(*pte) * 2, (u64)pte_val(*pte));
 out:
-	printk("\n");
+	printk(KERN_CONT "\n");
 }
 
 #else /* CONFIG_X86_64: */
@@ -565,7 +569,7 @@ static void dump_pagetable(unsigned long address)
 	if (bad_address(pgd))
 		goto bad;
 
-	printk("PGD %lx ", pgd_val(*pgd));
+	printk(KERN_ALERT "PGD %lx ", pgd_val(*pgd));
 
 	if (!pgd_present(*pgd))
 		goto out;
@@ -574,7 +578,7 @@ static void dump_pagetable(unsigned long address)
 	if (bad_address(p4d))
 		goto bad;
 
-	printk("P4D %lx ", p4d_val(*p4d));
+	printk(KERN_CONT "P4D %lx ", p4d_val(*p4d));
 	if (!p4d_present(*p4d) || p4d_large(*p4d))
 		goto out;
 
@@ -582,7 +586,7 @@ static void dump_pagetable(unsigned long address)
 	if (bad_address(pud))
 		goto bad;
 
-	printk("PUD %lx ", pud_val(*pud));
+	printk(KERN_CONT "PUD %lx ", pud_val(*pud));
 	if (!pud_present(*pud) || pud_large(*pud))
 		goto out;
 
@@ -590,7 +594,7 @@ static void dump_pagetable(unsigned long address)
 	if (bad_address(pmd))
 		goto bad;
 
-	printk("PMD %lx ", pmd_val(*pmd));
+	printk(KERN_CONT "PMD %lx ", pmd_val(*pmd));
 	if (!pmd_present(*pmd) || pmd_large(*pmd))
 		goto out;
 
@@ -598,12 +602,12 @@ static void dump_pagetable(unsigned long address)
 	if (bad_address(pte))
 		goto bad;
 
-	printk("PTE %lx", pte_val(*pte));
+	printk(KERN_CONT "PTE %lx", pte_val(*pte));
 out:
-	printk("\n");
+	printk(KERN_CONT "\n");
 	return;
 bad:
-	printk("BAD\n");
+	printk(KERN_CONT "BAD\n");
 }
 
 #endif /* CONFIG_X86_64 */
-- 
2.10.0.rc2.1.g053435c