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.leiz...@huawei.com>
---
 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


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