[rfc 1/4] mm: Introduce may_adjust_brk helper

From: Cyrill Gorcunov
Date: Thu Jul 24 2014 - 12:51:00 EST

To eliminate code duplication lets introduce may_adjust_brk
helper which we will use in brk() and prctl() syscalls.

Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Vagin <avagin@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
Cc: Vasiliy Kulikov <segoon@xxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
Cc: Julien Tinnes <jln@xxxxxxxxxx>
include/linux/mm.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)

Index: linux-2.6.git/include/linux/mm.h
--- linux-2.6.git.orig/include/linux/mm.h
+++ linux-2.6.git/include/linux/mm.h
@@ -18,6 +18,7 @@
#include <linux/pfn.h>
#include <linux/bit_spinlock.h>
#include <linux/shrinker.h>
+#include <linux/resource.h>

struct mempolicy;
struct anon_vma;
@@ -1780,6 +1781,19 @@ extern struct vm_area_struct *copy_vma(s
bool *need_rmap_locks);
extern void exit_mmap(struct mm_struct *);

+static inline int may_adjust_brk(unsigned long rlim,
+ unsigned long new_brk,
+ unsigned long start_brk,
+ unsigned long end_data,
+ unsigned long start_data)
+ if (rlim < RLIMIT_DATA) {
+ if (((new_brk - start_brk) + (end_data - start_data)) > rlim)
+ return -ENOSPC;
+ }
+ return 0;
extern int mm_take_all_locks(struct mm_struct *mm);
extern void mm_drop_all_locks(struct mm_struct *mm);

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