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authorRajman Mekaco <rajman.mekaco@gmail.com>2012-05-29 15:06:21 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-29 16:22:19 -0700
commit841e31e5cc6219d62054788faa289b6ed682d068 (patch)
tree6c6bbcf2be5082c5bdc71bfccad4d57be0e99126
parent4d67d860531ad5378dedfad7661c540f3365013d (diff)
downloadlinux-841e31e5cc6219d62054788faa289b6ed682d068.tar.bz2
mm/mmap.c: find_vma(): remove unnecessary if(mm) check
The "if (mm)" check is not required in find_vma, as the kernel code calls find_vma only when it is absolutely sure that the mm_struct arg to it is non-NULL. Remove the if(mm) check and adding the a WARN_ONCE(!mm) for now. This will serve the purpose of mandating that the execution context(user-mode/kernel-mode) be known before find_vma is called. Also fixed 2 checkpatch.pl errors in the declaration of the rb_node and vma_tmp local variables. I was browsing through the internet and read a discussion at https://lkml.org/lkml/2012/3/27/342 which discusses removal of the validation check within find_vma. Since no-one responded, I decided to send this patch with Andrew's suggestions. [akpm@linux-foundation.org: add remove-me comment] Signed-off-by: Rajman Mekaco <rajman.mekaco@gmail.com> Cc: Kautuk Consul <consul.kautuk@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mmap.c53
1 files changed, 27 insertions, 26 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index e8dcfc7de866..4a9c2a391e28 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1639,33 +1639,34 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
struct vm_area_struct *vma = NULL;
- if (mm) {
- /* Check the cache first. */
- /* (Cache hit rate is typically around 35%.) */
- vma = mm->mmap_cache;
- if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
- struct rb_node * rb_node;
-
- rb_node = mm->mm_rb.rb_node;
- vma = NULL;
-
- while (rb_node) {
- struct vm_area_struct * vma_tmp;
-
- vma_tmp = rb_entry(rb_node,
- struct vm_area_struct, vm_rb);
-
- if (vma_tmp->vm_end > addr) {
- vma = vma_tmp;
- if (vma_tmp->vm_start <= addr)
- break;
- rb_node = rb_node->rb_left;
- } else
- rb_node = rb_node->rb_right;
- }
- if (vma)
- mm->mmap_cache = vma;
+ if (WARN_ON_ONCE(!mm)) /* Remove this in linux-3.6 */
+ return NULL;
+
+ /* Check the cache first. */
+ /* (Cache hit rate is typically around 35%.) */
+ vma = mm->mmap_cache;
+ if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
+ struct rb_node *rb_node;
+
+ rb_node = mm->mm_rb.rb_node;
+ vma = NULL;
+
+ while (rb_node) {
+ struct vm_area_struct *vma_tmp;
+
+ vma_tmp = rb_entry(rb_node,
+ struct vm_area_struct, vm_rb);
+
+ if (vma_tmp->vm_end > addr) {
+ vma = vma_tmp;
+ if (vma_tmp->vm_start <= addr)
+ break;
+ rb_node = rb_node->rb_left;
+ } else
+ rb_node = rb_node->rb_right;
}
+ if (vma)
+ mm->mmap_cache = vma;
}
return vma;
}