[PATCHv2] kernel/crash: make parse_crashkernel()'s return value more indicant

[Pingfan Liu <kernelfans@gmail.com>]

At present, both return and crash_size should be checked to guarantee the
success of parse_crashkernel().

Take a close look at the cases, which causes crash_size=0. Beside syntax
error, three cases cause parsing to get crash_size=0.
-1st. in parse_crashkernel_mem(), the demanded crash size is bigger than
 system ram.
-2nd. in parse_crashkernel_mem(), the system ram size does not match any
 item in the range list.
-3rd. "crashkernel=0MB", which is impractical.

All these cases can be treated as invalid argument.

By this way, only need a simple check on return value of
parse_crashkernel().

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Greg Hackmann <ghackmann@android.com>
Cc: Stefan Agner <stefan@agner.ch>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Yangtao Li <tiny.windzz@gmail.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: x86@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
---
v1 -> v2: On error, return -EINVAL for all failure cases

 arch/arm/kernel/setup.c             |  2 +-
 arch/arm64/mm/init.c                |  2 +-
 arch/ia64/kernel/setup.c            |  2 +-
 arch/mips/kernel/setup.c            |  2 +-
 arch/powerpc/kernel/fadump.c        |  2 +-
 arch/powerpc/kernel/machine_kexec.c |  2 +-
 arch/s390/kernel/setup.c            |  2 +-
 arch/sh/kernel/machine_kexec.c      |  2 +-
 arch/x86/kernel/setup.c             |  4 ++--
 kernel/crash_core.c                 | 10 +++++++++-
 10 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 5d78b6a..2feab13 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -997,7 +997,7 @@ static void __init reserve_crashkernel(void)
 	total_mem = get_total_mem();
 	ret = parse_crashkernel(boot_command_line, total_mem,
 				&crash_size, &crash_base);
-	if (ret)
+	if (ret < 0)
 		return;
 
 	if (crash_base <= 0) {
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 6bc1350..240918c 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -79,7 +79,7 @@ static void __init reserve_crashkernel(void)
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&crash_size, &crash_base);
 	/* no crashkernel= or invalid value specified */
-	if (ret || !crash_size)
+	if (ret < 0)
 		return;
 
 	crash_size = PAGE_ALIGN(crash_size);
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 583a374..3bbb58b 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -277,7 +277,7 @@ static void __init setup_crashkernel(unsigned long total, int *n)
 
 	ret = parse_crashkernel(boot_command_line, total,
 			&size, &base);
-	if (ret = 0 && size > 0) {
+	if (!ret) {
 		if (!base) {
 			sort_regions(rsvd_region, *n);
 			*n = merge_regions(rsvd_region, *n);
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 8d1dc6c..168571b 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -715,7 +715,7 @@ static void __init mips_parse_crashkernel(void)
 	total_mem = get_total_mem();
 	ret = parse_crashkernel(boot_command_line, total_mem,
 				&crash_size, &crash_base);
-	if (ret != 0 || crash_size <= 0)
+	if (ret < 0)
 		return;
 
 	if (!memory_region_available(crash_base, crash_size)) {
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 45a8d0b..3571504 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -376,7 +376,7 @@ static inline unsigned long fadump_calculate_reserve_size(void)
 	 */
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 				&size, &base);
-	if (ret = 0 && size > 0) {
+	if (!ret) {
 		unsigned long max_size;
 
 		if (fw_dump.reserve_bootvar)
diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index 63f5a93..1697ad2 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -122,7 +122,7 @@ void __init reserve_crashkernel(void)
 	/* use common parsing */
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 			&crash_size, &crash_base);
-	if (ret = 0 && crash_size > 0) {
+	if (!ret) {
 		crashk_res.start = crash_base;
 		crashk_res.end = crash_base + crash_size - 1;
 	}
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 2c642af..d4bd61b 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -671,7 +671,7 @@ static void __init reserve_crashkernel(void)
 
 	crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
 	crash_size = ALIGN(crash_size, KEXEC_CRASH_MEM_ALIGN);
-	if (rc || crash_size = 0)
+	if (rc < 0)
 		return;
 
 	if (memblock.memory.regions[0].size < crash_size) {
diff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c
index 63d63a3..3c03240 100644
--- a/arch/sh/kernel/machine_kexec.c
+++ b/arch/sh/kernel/machine_kexec.c
@@ -157,7 +157,7 @@ void __init reserve_crashkernel(void)
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
 			&crash_size, &crash_base);
-	if (ret = 0 && crash_size > 0) {
+	if (!ret) {
 		crashk_res.start = crash_base;
 		crashk_res.end = crash_base + crash_size - 1;
 	}
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 3d872a5..592d5ad 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -526,11 +526,11 @@ static void __init reserve_crashkernel(void)
 
 	/* crashkernel=XM */
 	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
-	if (ret != 0 || crash_size <= 0) {
+	if (ret < 0) {
 		/* crashkernel=X,high */
 		ret = parse_crashkernel_high(boot_command_line, total_mem,
 					     &crash_size, &crash_base);
-		if (ret != 0 || crash_size <= 0)
+		if (ret < 0)
 			return;
 		high = true;
 	}
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 093c9f9..83ee4a9 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -108,8 +108,10 @@ static int __init parse_crashkernel_mem(char *cmdline,
 				return -EINVAL;
 			}
 		}
-	} else
+	} else {
 		pr_info("crashkernel size resulted in zero bytes\n");
+		return -EINVAL;
+	}
 
 	return 0;
 }
@@ -139,6 +141,8 @@ static int __init parse_crashkernel_simple(char *cmdline,
 		pr_warn("crashkernel: unrecognized char: %c\n", *cur);
 		return -EINVAL;
 	}
+	if (*crash_size = 0)
+		return -EINVAL;
 
 	return 0;
 }
@@ -181,6 +185,8 @@ static int __init parse_crashkernel_suffix(char *cmdline,
 		pr_warn("crashkernel: unrecognized char: %c\n", *cur);
 		return -EINVAL;
 	}
+	if (*crash_size = 0)
+		return -EINVAL;
 
 	return 0;
 }
@@ -266,6 +272,8 @@ static int __init __parse_crashkernel(char *cmdline,
 /*
  * That function is the entry point for command line parsing and should be
  * called from the arch-specific code.
+ * On success 0. On error for either syntax error or crash_size=0, -EINVAL is
+ * returned.
  */
 int __init parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
-- 
2.7.4