[RFC PATCH 0/5] kexec: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef

Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

I only modifies x86, arm, arm64 and riscv, other arch are not touched.
If the idea is accepted, I will modify all architectures code.

Jisheng Zhang (5):
  kexec: make crashk_res, crashk_low_res and crash_notes symbols always
    visible
  riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  x86/setup: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  arm64: mm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  arm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef

 arch/arm/kernel/setup.c |  7 +++----
 arch/arm64/mm/init.c    |  9 +++------
 arch/riscv/mm/init.c    |  6 ++----
 arch/x86/kernel/setup.c | 10 +++-------
 include/linux/kexec.h   | 12 ++++++------
 5 files changed, 17 insertions(+), 27 deletions(-)

-- 
2.34.1


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Make the forward declarations of crashk_res, crashk_low_res and
crash_notes always visible. Code referring to these symbols can then
just check for IS_ENABLED(CONFIG_KEXEC_CORE), instead of requiring
conditional compilation using an #ifdef, thus preparing to increase
compile coverage and simplify the code.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 include/linux/kexec.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0c994ae37729..58d1b58a971e 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h

@@ -20,6 +20,12 @@
 
 #include <uapi/linux/kexec.h>
 
+/* Location of a reserved region to hold the crash kernel.
+ */
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
+extern note_buf_t __percpu *crash_notes;
+
 #ifdef CONFIG_KEXEC_CORE
 #include <linux/list.h>
 #include <linux/compat.h>

@@ -350,12 +356,6 @@ extern int kexec_load_disabled;
 #define KEXEC_FILE_FLAGS	(KEXEC_FILE_UNLOAD | KEXEC_FILE_ON_CRASH | \
 				 KEXEC_FILE_NO_INITRAMFS)
 
-/* Location of a reserved region to hold the crash kernel.
- */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
-extern note_buf_t __percpu *crash_notes;
-
 /* flag to track if kexec reboot is in progress */
 extern bool kexec_in_progress;
 

-- 
2.34.1


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Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/mm/init.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index aeae7d6b2fee..704e2463e976 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c

@@ -755,7 +755,6 @@ static inline void setup_vm_final(void)
 }
 #endif /* CONFIG_MMU */
 
-#ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *

@@ -772,6 +771,8 @@ static void __init reserve_crashkernel(void)
 
 	int ret = 0;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
 	/*
 	 * Don't reserve a region for a crash kernel on a crash kernel
 	 * since it doesn't make much sense and we have limited memory

@@ -812,7 +813,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-#endif /* CONFIG_KEXEC_CORE */
 
 void __init paging_init(void)
 {

@@ -826,9 +826,7 @@ void __init misc_mem_init(void)
 	arch_numa_init();
 	sparse_init();
 	zone_sizes_init();
-#ifdef CONFIG_KEXEC_CORE
 	reserve_crashkernel();
-#endif
 	memblock_dump_all();
 }
 

-- 
2.34.1


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Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/x86/kernel/setup.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index c410be738ae7..56b738c1ca33 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c

@@ -390,8 +390,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
  * --------- Crashkernel reservation ------------------------------
  */
 
-#ifdef CONFIG_KEXEC_CORE
-
 /* 16M alignment for crash kernel regions */
 #define CRASH_ALIGN		SZ_16M
 

@@ -469,6 +467,9 @@ static void __init reserve_crashkernel(void)
 	bool high = false;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
 	total_mem = memblock_phys_mem_size();
 
 	/* crashkernel=XM */

@@ -534,11 +535,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.end   = crash_base + crash_size - 1;
 	insert_resource(&iomem_resource, &crashk_res);
 }
-#else
-static void __init reserve_crashkernel(void)
-{
-}
-#endif
 
 static struct resource standard_io_resources[] = {
 	{ .name = "dma1", .start = 0x00, .end = 0x1f,

-- 
2.34.1


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Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/arm64/mm/init.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index a8834434af99..b4b8b4dc2d31 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -64,7 +64,6 @@ EXPORT_SYMBOL(memstart_addr);
  */
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
-#ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
  *

@@ -78,6 +77,9 @@ static void __init reserve_crashkernel(void)
 	unsigned long long crash_max = arm64_dma_phys_limit;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
 	/* no crashkernel= or invalid value specified */

@@ -110,11 +112,6 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 }
-#else
-static void __init reserve_crashkernel(void)
-{
-}
-#endif /* CONFIG_KEXEC_CORE */
 
 /*
  * Return the maximum physical address for a zone accessible by the given bits

-- 
2.34.1


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On Fri, Dec 03, 2021 at 01:11:56PM +0800, Jisheng Zhang wrote:

Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>

As long as it still compiles:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

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Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/arm/kernel/setup.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 284a80c0b6e1..f9a054a344c0 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c

@@ -973,7 +973,6 @@ static int __init init_machine_late(void)
 }
 late_initcall(init_machine_late);
 
-#ifdef CONFIG_KEXEC
 /*
  * The crash region must be aligned to 128MB to avoid
  * zImage relocating below the reserved region.

@@ -1001,6 +1000,9 @@ static void __init reserve_crashkernel(void)
 	unsigned long long total_mem;
 	int ret;
 
+	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
+		return;
+
 	total_mem = get_total_mem();
 	ret = parse_crashkernel(boot_command_line, total_mem,
 				&crash_size, &crash_base);

@@ -1056,9 +1058,6 @@ static void __init reserve_crashkernel(void)
 		insert_resource(&iomem_resource, &crashk_boot_res);
 	}
 }
-#else
-static inline void reserve_crashkernel(void) {}
-#endif /* CONFIG_KEXEC */
 
 void __init hyp_mode_check(void)
 {

-- 
2.34.1


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On Fri, Dec 03, 2021 at 01:11:57PM +0800, Jisheng Zhang wrote:

Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the
code and increase compile coverage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>

Reviewed-by: Russell King (Oracle) <redacted>

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Hi Jisheng,

On Fri, 3 Dec 2021 at 06:22, Jisheng Zhang [off-list ref] wrote:

Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE"
by a check for "IS_ENABLED(CONFIG_BLK_DEV_INITRD)", to simplify the

The patch looks fine, but I think you mean
IS_ENABLED(CONFIG_KEXEC_CORE) here, not CONFIG_BLK_DEV_INITRD.

/Emil

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