2007-06-15 15:23:26

by Jason Baron

Subject: [PATCH] madvise_need_mmap_write() usage

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?

thanks,

-Jason


Signed-off-by: Jason Baron <[email protected]>

diff --git a/mm/madvise.c b/mm/madvise.c
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -287,9 +287,10 @@ 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))
+ if (write = madvise_need_mmap_write(behavior))
down_write(&current->mm->mmap_sem);
else
down_read(&current->mm->mmap_sem);
@@ -354,7 +355,7 @@ 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);

2007-06-16 19:41:39

by Christoph Hellwig

Subject: Re: [PATCH] madvise_need_mmap_write() usage

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.

2007-06-18 15:38:50

by Jason Baron

Subject: Re: [PATCH] madvise_need_mmap_write() usage

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 <[email protected]>


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);

2007-06-18 16:52:17

by Nish Aravamudan

Subject: Re: [PATCH] madvise_need_mmap_write() usage

On 6/18/07, Jason Baron <[email protected]> wrote:
>
> 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:

You should always append the full patch, both the diff and the
rationale, I think. Even though it's quoted above, might make less
work for Andrew to pull in.

Thanks,
Nish