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

Dmitry Safonov
2020-11-24T00:30:00Z

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