From: Liam R. Howlett Date: Mon, 1 Mar 2021 19:01:06 +0000 (-0500) Subject: mm: Add vma_lookup() X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=72b4dad4a2ccceb46355d0a9f114e584a2e197df;p=users%2Fjedix%2Flinux-maple.git mm: Add vma_lookup() Many places in the kernel use find_vma() to get a vma and then check the start address of the vma to ensure the next vma was not returned. Other places use the find_vma_intersection() call with add, addr + 1 as the range; looking for just the vma at a specific address. The third use of find_vma() is by developers who do not know that the function starts searching at the provided address upwards for the next vma. This results in a bug that is often overlooked for a long time. Adding the new vma_lookup() function will allow for cleaner code by removing the find_vma() calls which check limits, making find_vma_intersection() calls of a single address to be shorter, and potentially reduce the incorrect uses of find_vma(). Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Liam R. Howlett --- diff --git a/include/linux/mm.h b/include/linux/mm.h index 25b9041f9925..7f7dff6ad884 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2689,6 +2689,19 @@ static inline struct vm_area_struct * find_vma_intersection(struct mm_struct * m return vma; } +/** + * vma_lookup() - Find a VMA at a specific address + * @mm: The process address space. + * @addr: The user address. + * + * Return: The vm_area_struct at the given address, %NULL otherwise. + */ +static inline +struct vm_area_struct *vma_lookup(struct mm_struct *mm, unsigned long addr) +{ + return find_vma_intersection(mm, addr, addr + 1); +} + static inline unsigned long vm_start_gap(struct vm_area_struct *vma) { unsigned long vm_start = vma->vm_start;