Re: [PATCH] madvise_need_mmap_write() usage

From: Jason Baron
Date: Mon Jun 18 2007 - 11:38:50 EST



On Sat, 16 Jun 2007, Christoph Hellwig wrote:

> On Fri, Jun 15, 2007 at 11:20:31AM -0400, Jason Baron wrote:
> > hi,
> >
> > i was just looking at the new madvise_need_mmap_write() call...can we
> > avoid an extra case statement and function call as follows?
>
> Sounds like a good idea, but please move the assignment out of the
> conditional.
>

ok, here's an updated version:


Signed-off-by: Jason Baron <jbaron@xxxxxxxxxx>


diff --git a/mm/madvise.c b/mm/madvise.c
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -287,9 +287,11 @@ asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)
struct vm_area_struct * vma, *prev;
int unmapped_error = 0;
int error = -EINVAL;
+ int write;
size_t len;

- if (madvise_need_mmap_write(behavior))
+ write = madvise_need_mmap_write(behavior);
+ if (write)
down_write(&current->mm->mmap_sem);
else
down_read(&current->mm->mmap_sem);
@@ -354,7 +356,7 @@ asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)
vma = find_vma(current->mm, start);
}
out:
- if (madvise_need_mmap_write(behavior))
+ if (write)
up_write(&current->mm->mmap_sem);
else
up_read(&current->mm->mmap_sem);
-
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