[Patch v2 2/3] check if crashk_res_low exists when exclude it from crash mem ranges

[Baoquan He <bhe@redhat.com>]

Add a check if crashk_res_low exists just like GART region does. If
crashk_res_low doesn't exist, calling exclude_mem_range is unnecessary.

Meanwhile, since crashk_res_low has been initialized at definition, it's
safe just use "if (crashk_low_res.end)" to check if it's exist. And this
can make it consistent with other places of check.

Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
---
 arch/x86/kernel/crash.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index a618fcd..f5ab56d 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -237,7 +237,7 @@ static void fill_up_crash_elf_data(struct crash_elf_data *ced,
 	ced->max_nr_ranges++;
 
 	/* If crashk_low_res is not 0, another range split possible */
-	if (crashk_low_res.end != 0)
+	if (crashk_low_res.end)
 		ced->max_nr_ranges++;
 }
 
@@ -335,9 +335,11 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced,
 	if (ret)
 		return ret;
 
-	ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-	if (ret)
-		return ret;
+	if (crashk_low_res.end) {
+		ret = exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+		if (ret)
+			return ret;
+	}
 
 	/* Exclude GART region */
 	if (ced->gart_end) {
-- 
1.8.5.3