[PATCH v2 11/19] mm/mmap: Make vm_special_mapping::mremap return void

From: Dmitry Safonov <dima@arista.com>
To: linux-kernel@vger.kernel.org
Cc: Dmitry Safonov <0x7f454c46@gmail.com>,
	Dmitry Safonov <dima@arista.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Guo Ren <guoren@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Ingo Molnar <mingo@redhat.com>, Oleg Nesterov <oleg@redhat.com>,
	Russell King <linux@armlinux.org.uk>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Will Deacon <will@kernel.org>,
	x86@kernel.org
Subject: [PATCH v2 11/19] mm/mmap: Make vm_special_mapping::mremap return void
Date: Tue, 24 Nov 2020 00:29:24 +0000	[thread overview]
Message-ID: <20201124002932.1220517-12-dima@arista.com> (raw)
In-Reply-To: <20201124002932.1220517-1-dima@arista.com>

Previously .mremap() callback needed (int) return to provide way to
restrict resizing of a special mapping. Now it's restricted by
providing .may_split = special_mapping_split.

Removing (int) return simplifies further changes to
special_mapping_mremap() as it won't need save ret code from the
callback. Also, it removes needless `return 0` from callbacks.

Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 arch/arm/kernel/process.c | 3 +--
 arch/arm64/kernel/vdso.c  | 4 +---
 arch/mips/vdso/genvdso.c  | 3 +--
 arch/x86/entry/vdso/vma.c | 4 +---
 include/linux/mm_types.h  | 2 +-
 mm/mmap.c                 | 2 +-
 6 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0e90cba8ac7a..5f4eced738f5 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -376,11 +376,10 @@ static unsigned long sigpage_addr(const struct mm_struct *mm,
 static struct page *signal_page;
 extern struct page *get_signal_page(void);
 
-static int sigpage_mremap(const struct vm_special_mapping *sm,
+static void sigpage_mremap(const struct vm_special_mapping *sm,
 		struct vm_area_struct *new_vma)
 {
 	current->mm->context.sigpage = new_vma->vm_start;
-	return 0;
 }
 
 static const struct vm_special_mapping sigpage_mapping = {
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 666338724a07..91c1b7c716b7 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -78,12 +78,10 @@ static union {
 } vdso_data_store __page_aligned_data;
 struct vdso_data *vdso_data = vdso_data_store.data;
 
-static int vdso_mremap(const struct vm_special_mapping *sm,
+static void vdso_mremap(const struct vm_special_mapping *sm,
 		struct vm_area_struct *new_vma)
 {
 	current->mm->context.vdso = (void *)new_vma->vm_start;
-
-	return 0;
 }
 
 static int __vdso_init(enum vdso_abi abi)
diff --git a/arch/mips/vdso/genvdso.c b/arch/mips/vdso/genvdso.c
index 09e30eb4be86..0303d30cde03 100644
--- a/arch/mips/vdso/genvdso.c
+++ b/arch/mips/vdso/genvdso.c
@@ -259,13 +259,12 @@ int main(int argc, char **argv)
 	fprintf(out_file, "#include <linux/linkage.h>\n");
 	fprintf(out_file, "#include <linux/mm.h>\n");
 	fprintf(out_file, "#include <asm/vdso.h>\n");
-	fprintf(out_file, "static int vdso_mremap(\n");
+	fprintf(out_file, "static void vdso_mremap(\n");
 	fprintf(out_file, "	const struct vm_special_mapping *sm,\n");
 	fprintf(out_file, "	struct vm_area_struct *new_vma)\n");
 	fprintf(out_file, "{\n");
 	fprintf(out_file, "	current->mm->context.vdso =\n");
 	fprintf(out_file, "	(void *)(new_vma->vm_start);\n");
-	fprintf(out_file, "	return 0;\n");
 	fprintf(out_file, "}\n");
 
 	/* Write out the stripped VDSO data. */
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 5b9020742e66..65780a0164e3 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -86,15 +86,13 @@ static void vdso_fix_landing(const struct vdso_image *image,
 #endif
 }
 
-static int vdso_mremap(const struct vm_special_mapping *sm,
+static void vdso_mremap(const struct vm_special_mapping *sm,
 		struct vm_area_struct *new_vma)
 {
 	const struct vdso_image *image = current->mm->context.vdso_image;
 
 	vdso_fix_landing(image, new_vma);
 	current->mm->context.vdso = (void __user *)new_vma->vm_start;
-
-	return 0;
 }
 
 #ifdef CONFIG_TIME_NS
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 65df8abd90bd..95a257927dae 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -780,7 +780,7 @@ struct vm_special_mapping {
 				struct vm_area_struct *vma,
 				struct vm_fault *vmf);
 
-	int (*mremap)(const struct vm_special_mapping *sm,
+	void (*mremap)(const struct vm_special_mapping *sm,
 		     struct vm_area_struct *new_vma);
 };
 
diff --git a/mm/mmap.c b/mm/mmap.c
index d0d458632c1b..17fe59a9780b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3433,7 +3433,7 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma,
 		return -EFAULT;
 
 	if (sm->mremap)
-		return sm->mremap(sm, new_vma);
+		sm->mremap(sm, new_vma);
 
 	return 0;
 }
-- 
2.29.2

