3 files changed, 32 insertions, 20 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index c90d3cd2728c..c73a7df5d37f 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -932,26 +932,8 @@ u64 efi_mem_attributes(unsigned long phys_addr)
 
 static int __init parse_efi_cmdline(char *str)
 {
-        if (*str == '=')
-                str++;
-
-        while (*str) {
-                if (!strncmp(str, "old_map", 7)) {
-                        set_bit(EFI_OLD_MEMMAP, &efi.flags);
-                        str += strlen("old_map");
-                }
-
-                /*
-                 * Skip any options we don't understand. Presumably
-                 * they apply to the EFI boot stub.
-                 */
-                while (*str && *str != ',')
-                        str++;
-
-                /* If we hit a delimiter, skip it */
-                if (*str == ',')
-                        str++;
-        }
+        if (parse_option_str(str, "old_map"))
+                set_bit(EFI_OLD_MEMMAP, &efi.flags);
 
         return 0;
 }
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 95624bed87ef..f66427ef0628 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -407,6 +407,7 @@ int vsscanf(const char *, const char *, va_list);
 extern int get_option(char **str, int *pint);
 extern char *get_options(const char *str, int nints, int *ints);
 extern unsigned long long memparse(const char *ptr, char **retptr);
+extern bool parse_option_str(const char *str, const char *option);
 
 extern int core_kernel_text(unsigned long addr);
 extern int core_kernel_data(unsigned long addr);
diff --git a/lib/cmdline.c b/lib/cmdline.c
index 76a712e6e20e..8f13cf73c2ec 100644
--- a/lib/cmdline.c
+++ b/lib/cmdline.c
@@ -160,3 +160,32 @@ unsigned long long memparse(const char *ptr, char **retptr)
         return ret;
 }
 EXPORT_SYMBOL(memparse);
+
+/**
+ *      parse_option_str - Parse a string and check an option is set or not
+ *      @str: String to be parsed
+ *      @option: option name
+ *
+ *      This function parses a string containing a comma-separated list of
+ *      strings like a=b,c.
+ *
+ *      Return true if there's such option in the string, or return false.
+ */
+bool parse_option_str(const char *str, const char *option)
+{
+        while (*str) {
+                if (!strncmp(str, option, strlen(option))) {
+                        str += strlen(option);
+                        if (!*str || *str == ',')
+                                return true;
+                }
+
+                while (*str && *str != ',')
+                        str++;
+
+                if (*str == ',')
+                        str++;
+        }
+
+        return false;
+}