[PATCH] madvise_need_mmap_write() usage

[PATCH] madvise_need_mmap_write() usage

[Jason Baron]

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 <jbaron@redhat.com>

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);

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Re: [PATCH] madvise_need_mmap_write() usage

[Christoph Hellwig]

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.

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Re: [PATCH] madvise_need_mmap_write() usage

[Jason Baron]

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@redhat.com>


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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Re: [PATCH] madvise_need_mmap_write() usage

[Nish Aravamudan]

On 6/18/07, Jason Baron <jbaron@redhat.com> 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

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