[PATCH] x86: trim mtrr don't close gap for resource allocation

["Yinghai Lu" <yhlu.kernel@gmail.com>]

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[PATCH] x86: trim mtrr don't close gap for resource allocation.

for
	http://bugzilla.kernel.org/show_bug.cgi?id=10232

use update_memory_range instead of add_memory_range directly
to avoid closing that gap.

Signed-off-by: Yinghai Lu <yhlu.kenrel@gmail.com>

Index: linux-2.6/arch/x86/kernel/cpu/mtrr/main.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/mtrr/main.c
+++ linux-2.6/arch/x86/kernel/cpu/mtrr/main.c
@@ -711,7 +711,8 @@ int __init mtrr_trim_uncached_memory(uns
 		trim_size = end_pfn;
 		trim_size <<= PAGE_SHIFT;
 		trim_size -= trim_start;
-		add_memory_region(trim_start, trim_size, E820_RESERVED);
+		update_memory_range(trim_start, trim_size, E820_RAM,
+					E820_RESERVED);
 		update_e820();
 		return 1;
 	}
Index: linux-2.6/arch/x86/kernel/e820_32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820_32.c
+++ linux-2.6/arch/x86/kernel/e820_32.c
@@ -736,6 +736,32 @@ static int __init parse_memmap(char *arg
 	return 0;
 }
 early_param("memmap", parse_memmap);
+void __init update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type)
+{
+	int i;
+
+	BUG_ON(old_type == new_type);
+
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		u64 final_start, final_end;
+		if (ei->type != old_type)
+			continue;
+		/* totally covered? */
+		if (ei->addr >= start && ei->size <= size) {
+			ei->type = new_type;
+			continue;
+		}
+		/* partially covered */
+		final_start = max(start, ei->addr);
+		final_end = min(start + size, ei->addr + ei->size);
+		if (final_start >= final_end)
+			continue;
+		add_memory_region(final_start, final_end - final_start,
+					 new_type);
+	}
+}
 void __init update_e820(void)
 {
 	u8 nr_map;
Index: linux-2.6/arch/x86/kernel/e820_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820_64.c
+++ linux-2.6/arch/x86/kernel/e820_64.c
@@ -731,6 +731,33 @@ void __init finish_e820_parsing(void)
 	}
 }
 
+void __init update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type)
+{
+	int i;
+
+	BUG_ON(old_type == new_type);
+
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		u64 final_start, final_end;
+		if (ei->type != old_type)
+			continue;
+		/* totally covered? */
+		if (ei->addr >= start && ei->size <= size) {
+			ei->type = new_type;
+			continue;
+		}
+		/* partially covered */
+		final_start = max(start, ei->addr);
+		final_end = min(start + size, ei->addr + ei->size);
+		if (final_start >= final_end)
+			continue;
+		add_memory_region(final_start, final_end - final_start,
+					 new_type);
+	}
+}
+
 void __init update_e820(void)
 {
 	u8 nr_map;
Index: linux-2.6/include/asm-x86/e820_32.h
===================================================================
--- linux-2.6.orig/include/asm-x86/e820_32.h
+++ linux-2.6/include/asm-x86/e820_32.h
@@ -28,6 +28,8 @@ extern void find_max_pfn(void);
 extern void register_bootmem_low_pages(unsigned long max_low_pfn);
 extern void add_memory_region(unsigned long long start,
 			      unsigned long long size, int type);
+extern void update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type);
 extern void e820_register_memory(void);
 extern void limit_regions(unsigned long long size);
 extern void print_memory_map(char *who);
Index: linux-2.6/include/asm-x86/e820_64.h
===================================================================
--- linux-2.6.orig/include/asm-x86/e820_64.h
+++ linux-2.6/include/asm-x86/e820_64.h
@@ -18,6 +18,8 @@ extern unsigned long find_e820_area(unsi
 				    unsigned long size, unsigned long align);
 extern void add_memory_region(unsigned long start, unsigned long size, 
 			      int type);
+extern void update_memory_range(u64 start, u64 size, unsigned old_type,
+				unsigned new_type);
 extern void setup_memory_region(void);
 extern void contig_e820_setup(void); 
 extern unsigned long e820_end_of_ram(void);