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List: linux-parisc
Subject: Re: [patch 1/1] mm: use vm_unmapped_area() on parisc architecture
From: Helge Deller <deller () gmx ! de>
Date: 2013-02-25 21:15:34
Message-ID: 512BD476.1050409 () gmx ! de
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On 02/22/2013 12:12 AM, akpm@linux-foundation.org wrote:
> From: Michel Lespinasse <walken@google.com>
> Subject: mm: use vm_unmapped_area() on parisc architecture
>
> Update the parisc arch_get_unmapped_area function to make use of
> vm_unmapped_area() instead of implementing a brute force search.
>
> Signed-off-by: Michel Lespinasse <walken@google.com>
> Acked-by: Rik van Riel <riel@redhat.com>
> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
> Cc: Helge Deller <deller@gmx.de>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
James had two comments regarding this patch:
https://patchwork.kernel.org/patch/2027451/
Anyway, given the fact that this patch is a nice cleanup, that it does not do more
wrong than what was maybe wrong before, and that I tested a 32- and 64bit kernel
with that patch, I would say:
Acked-by: Helge Deller <deller@gmx.de>
> ---
>
> arch/parisc/kernel/sys_parisc.c | 46 +++++++++++-------------------
> 1 file changed, 17 insertions(+), 29 deletions(-)
>
> diff -puN arch/parisc/kernel/sys_parisc.c~mm-use-vm_unmapped_area-on-parisc-architecture \
> arch/parisc/kernel/sys_parisc.c
> --- a/arch/parisc/kernel/sys_parisc.c~mm-use-vm_unmapped_area-on-parisc-architecture
>
> +++ a/arch/parisc/kernel/sys_parisc.c
> @@ -35,18 +35,15 @@
>
> static unsigned long get_unshared_area(unsigned long addr, unsigned long len)
> {
> - struct vm_area_struct *vma;
> + struct vm_unmapped_area_info info;
>
> - addr = PAGE_ALIGN(addr);
> -
> - for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
> - /* At this point: (!vma || addr < vma->vm_end). */
> - if (TASK_SIZE - len < addr)
> - return -ENOMEM;
> - if (!vma || addr + len <= vma->vm_start)
> - return addr;
> - addr = vma->vm_end;
> - }
> + info.flags = 0;
> + info.length = len;
> + info.low_limit = PAGE_ALIGN(addr);
> + info.high_limit = TASK_SIZE;
> + info.align_mask = 0;
> + info.align_offset = 0;
> + return vm_unmapped_area(&info);
> }
>
> #define DCACHE_ALIGN(addr) (((addr) + (SHMLBA - 1)) &~ (SHMLBA - 1))
> @@ -63,30 +60,21 @@ static unsigned long get_unshared_area(u
> */
> static int get_offset(struct address_space *mapping)
> {
> - int offset = (unsigned long) mapping << (PAGE_SHIFT - 8);
> - return offset & 0x3FF000;
> + return (unsigned long) mapping >> 8;
> }
>
> static unsigned long get_shared_area(struct address_space *mapping,
> unsigned long addr, unsigned long len, unsigned long pgoff)
> {
> - struct vm_area_struct *vma;
> - int offset = mapping ? get_offset(mapping) : 0;
> -
> - offset = (offset + (pgoff << PAGE_SHIFT)) & 0x3FF000;
> + struct vm_unmapped_area_info info;
>
> - addr = DCACHE_ALIGN(addr - offset) + offset;
> -
> - for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
> - /* At this point: (!vma || addr < vma->vm_end). */
> - if (TASK_SIZE - len < addr)
> - return -ENOMEM;
> - if (!vma || addr + len <= vma->vm_start)
> - return addr;
> - addr = DCACHE_ALIGN(vma->vm_end - offset) + offset;
> - if (addr < vma->vm_end) /* handle wraparound */
> - return -ENOMEM;
> - }
> + info.flags = 0;
> + info.length = len;
> + info.low_limit = PAGE_ALIGN(addr);
> + info.high_limit = TASK_SIZE;
> + info.align_mask = PAGE_MASK & (SHMLBA - 1);
> + info.align_offset = (get_offset(mapping) + pgoff) << PAGE_SHIFT;
> + return vm_unmapped_area(&info);
> }
>
> unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
> _
>
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