linux-kernel - [PATCH 1/5] x86/boot/e820: Fix and clean up e820

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Date:   Wed,  1 Feb 2017 10:51:13 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 1/5] x86/boot/e820: Fix and clean up e820_type switch() statements

A test-build of e820.o with -Wswitch-enum shows the following warnings:

  arch/x86/kernel/e820.c: In function ‘e820_type_to_string’:
  arch/x86/kernel/e820.c:965:2: warning: enumeration value ‘E820_TYPE_RESERVED’ not handled in switch [-Wswitch-enum]
    switch (entry->type) {
    ^

  arch/x86/kernel/e820.c: In function ‘e820_type_to_iomem_type’:
  arch/x86/kernel/e820.c:979:2: warning: enumeration value ‘E820_TYPE_RESERVED’ not handled in switch [-Wswitch-enum]
    switch (entry->type) {
    ^

  arch/x86/kernel/e820.c: In function ‘e820_type_to_iores_desc’:
  arch/x86/kernel/e820.c:993:2: warning: enumeration value ‘E820_TYPE_RESERVED’ not handled in switch [-Wswitch-enum]
    switch (entry->type) {
    ^

  arch/x86/kernel/e820.c: In function ‘do_mark_busy’:
  arch/x86/kernel/e820.c:1015:2: warning: enumeration value ‘E820_TYPE_RAM’ not handled in switch [-Wswitch-enum]
    switch (type) {
	    ^

Here's the four warnings:

  - The one in e820_type_to_string() is a borderline bug, we should differentiate
    known-reserved E820 types from unknown types. Fix it by printing a separate
    message for unknown E820 types.

  - The ones in e820_type_to_iomem_type(), e820_type_to_iores_desc() and
    do_mark_busy() are worth documenting, at least to the extent of
    enumerating them explicitly.

Cc: Alex Thorlton <athorlton@....com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Huang, Ying <ying.huang@...el.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul Jackson <pj@....com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rafael J. Wysocki <rjw@...k.pl>
Cc: Tejun Heo <tj@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Wei Yang <richard.weiyang@...il.com>
Cc: Yinghai Lu <yinghai@...nel.org>
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/e820.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index d2c6468a8d38..20834a81854e 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -970,7 +970,8 @@ static const char *__init e820_type_to_string(struct e820_entry *entry)
 	case E820_TYPE_UNUSABLE:	return "Unusable memory";
 	case E820_TYPE_PRAM:		return "Persistent Memory (legacy)";
 	case E820_TYPE_PMEM:		return "Persistent Memory";
-	default:			return "Reserved";
+	case E820_TYPE_RESERVED:	return "Reserved";
+	default:			return "Unknown E820 type";
 	}
 }
 
@@ -984,6 +985,7 @@ static unsigned long __init e820_type_to_iomem_type(struct e820_entry *entry)
 	case E820_TYPE_UNUSABLE:	/* Fall-through: */
 	case E820_TYPE_PRAM:		/* Fall-through: */
 	case E820_TYPE_PMEM:		/* Fall-through: */
+	case E820_TYPE_RESERVED:	/* Fall-through: */
 	default:			return IORESOURCE_MEM;
 	}
 }
@@ -998,11 +1000,12 @@ static unsigned long __init e820_type_to_iores_desc(struct e820_entry *entry)
 	case E820_TYPE_RESERVED_KERN:	/* Fall-through: */
 	case E820_TYPE_RAM:		/* Fall-through: */
 	case E820_TYPE_UNUSABLE:	/* Fall-through: */
+	case E820_TYPE_RESERVED:	/* Fall-through: */
 	default:			return IORES_DESC_NONE;
 	}
 }
 
-static bool __init do_mark_busy(u32 type, struct resource *res)
+static bool __init do_mark_busy(enum e820_type type, struct resource *res)
 {
 	/* this is the legacy bios/dos rom-shadow + mmio region */
 	if (res->start < (1ULL<<20))
@@ -1017,6 +1020,11 @@ static bool __init do_mark_busy(u32 type, struct resource *res)
 	case E820_TYPE_PRAM:
 	case E820_TYPE_PMEM:
 		return false;
+	case E820_TYPE_RESERVED_KERN:
+	case E820_TYPE_RAM:
+	case E820_TYPE_ACPI:
+	case E820_TYPE_NVS:
+	case E820_TYPE_UNUSABLE:
 	default:
 		return true;
 	}
-- 
2.7.4