[PATCH v18 05/17] x86/setup: Use parse_crashkernel_in_order() to make code logic clear

[Zhen Lei <thunder.leizhen@xxxxxxxxxx>]

Currently, the parsing of "crashkernel=X,high" and the parsing of
"crashkernel=X,low" are not in the same function, but they are strongly
dependent, which affects readability. Use parse_crashkernel_in_order() to
bring them together.

In addition, the operation to ensure at least 256M low memory is moved out
of reserve_craskernel_low() so that it only needs to focus on low memory
allocation.

Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
---
 arch/x86/kernel/setup.c | 69 ++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 39 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index f997074d36f2484..07a58313db5c5f7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -393,32 +393,16 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 #ifdef CONFIG_KEXEC_CORE
 
 #ifdef CONFIG_X86_64
-static int __init reserve_crashkernel_low(void)
+static int __init reserve_crashkernel_low(unsigned long long low_size)
 {
-	unsigned long long base, low_base = 0, low_size = 0;
+	unsigned long long low_base = 0;
 	unsigned long low_mem_limit;
-	int ret;
 
 	low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
 
-	/* crashkernel=Y,low */
-	ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
-	if (ret) {
-		/*
-		 * two parts from kernel/dma/swiotlb.c:
-		 * -swiotlb size: user-specified with swiotlb= or default.
-		 *
-		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
-		 * to 8M for other buffers that may need to stay low too. Also
-		 * make sure we allocate enough extra low memory so that we
-		 * don't run out of DMA buffers for 32-bit devices.
-		 */
-		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-	} else {
-		/* passed with crashkernel=0,low ? */
-		if (!low_size)
-			return 0;
-	}
+	/* passed with crashkernel=0,low ? */
+	if (!low_size)
+		return 0;
 
 	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
 	if (!low_base) {
@@ -457,7 +441,6 @@ static int __init reserve_crashkernel_low(void)
  * Returns the status flag of the parsing result of "crashkernel=", such as
  * CRASHKERNEL_MEM_NONE, CRASHKERNEL_MEM_HIGH.
  */
-__maybe_unused
 static int __init parse_crashkernel_in_order(char *cmdline,
 					     unsigned long long system_ram,
 					     unsigned long long *crash_size,
@@ -492,22 +475,15 @@ static int __init parse_crashkernel_in_order(char *cmdline,
 
 static void __init reserve_crashkernel(void)
 {
-	unsigned long long crash_size, crash_base, total_mem;
-	bool high = false;
-	int ret;
+	unsigned long long crash_size, crash_base, total_mem, low_size;
+	int flag;
 
 	total_mem = memblock_phys_mem_size();
 
-	/* crashkernel=XM */
-	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
-	if (ret != 0 || crash_size <= 0) {
-		/* crashkernel=X,high */
-		ret = parse_crashkernel_high(boot_command_line, total_mem,
-					     &crash_size, &crash_base);
-		if (ret != 0 || crash_size <= 0)
-			return;
-		high = true;
-	}
+	flag = parse_crashkernel_in_order(boot_command_line, total_mem,
+					  &crash_size, &crash_base, &low_size);
+	if (flag == CRASHKERNEL_MEM_NONE)
+		return;
 
 	/* 0 means: find the address automatically */
 	if (!crash_base) {
@@ -519,7 +495,7 @@ static void __init reserve_crashkernel(void)
 		 * So try low memory first and fall back to high memory
 		 * unless "crashkernel=size[KMG],high" is specified.
 		 */
-		if (!high)
+		if (!(flag & CRASHKERNEL_MEM_HIGH))
 			crash_base = memblock_phys_alloc_range(crash_size,
 						CRASH_ALIGN, CRASH_ALIGN,
 						CRASH_ADDR_LOW_MAX);
@@ -543,9 +519,24 @@ static void __init reserve_crashkernel(void)
 	}
 
 #ifdef CONFIG_X86_64
-	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
-		memblock_phys_free(crash_base, crash_size);
-		return;
+	if (crash_base >= (1ULL << 32)) {
+		if (!(flag & CRASHKERNEL_MEM_LOW)) {
+			/*
+			 * two parts from kernel/dma/swiotlb.c:
+			 * -swiotlb size: user-specified with swiotlb= or default.
+			 *
+			 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
+			 * to 8M for other buffers that may need to stay low too. Also
+			 * make sure we allocate enough extra low memory so that we
+			 * don't run out of DMA buffers for 32-bit devices.
+			 */
+			low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
+		}
+
+		if (reserve_crashkernel_low(low_size)) {
+			memblock_phys_free(crash_base, crash_size);
+			return;
+		}
 	}
 #endif
 
-- 
2.25.1