linux-kernel - Re: [PATCH] madvise_need_mmap

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Message-ID: <Pine.LNX.4.64.0706181132020.23021@dhcp83-20.boston.redhat.com>
Date:	Mon, 18 Jun 2007 11:35:15 -0400 (EDT)
From:	Jason Baron <jbaron@...hat.com>
To:	Christoph Hellwig <hch@...radead.org>
cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	nickpiggin@...oo.com.au, Rik van Riel <riel@...hat.com>
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 <jbaron@...hat.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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