[PATCH 1/4] kdump: add helper parse_crashkernel_high_low()

[Zhen Lei]

The bootup command line option crashkernel=Y,low is valid only when
crashkernel=X,high is specified. Putting their parsing into a separate
function makes the code logic clearer and easier to understand the strong
dependencies between them.

Signed-off-by: Zhen Lei <thunder.leizhen at huawei.com>
---
 include/linux/crash_core.h |  3 +++
 kernel/crash_core.c        | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index de62a722431e7db..2d3a64761d18998 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -83,5 +83,8 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
+int __init parse_crashkernel_high_low(char *cmdline,
+				      unsigned long long *high_size,
+				      unsigned long long *low_size);
 
 #endif /* LINUX_CRASH_CORE_H */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index eb53f5ec62c900f..8ab59a0e04f178f 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -295,6 +295,41 @@ int __init parse_crashkernel_low(char *cmdline,
 				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
 }
 
+/**
+ * parse_crashkernel_high_low - Parsing "crashkernel=X,high" and possible
+ *				"crashkernel=Y,low".
+ * @cmdline:	The bootup command line.
+ * @high_size:	Save the memory size specified by "crashkernel=X,high".
+ * @low_size:	Save the memory size specified by "crashkernel=Y,low" or "-1"
+		if it's not specified.
+ *
+ * Returns 0 on success, else a negative status code.
+ */
+int __init parse_crashkernel_high_low(char *cmdline,
+				      unsigned long long *high_size,
+				      unsigned long long *low_size)
+{
+	int ret;
+	unsigned long long base;
+
+	BUG_ON(!high_size || !low_size);
+
+	/* crashkernel=X,high */
+	ret = parse_crashkernel_high(cmdline, 0, high_size, &base);
+	if (ret)
+		return ret;
+
+	if (*high_size <= 0)
+		return -EINVAL;
+
+	/* crashkernel=Y,low */
+	ret = parse_crashkernel_low(cmdline, 0, low_size, &base);
+	if (ret)
+		*low_size = -1;
+
+	return 0;
+}
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
-- 
2.25.1