mm: Create utility function for accessing a tasks commandline value

introduce get_cmdline() for retreiving the value of a processes
proc/self/cmdline value.

Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Richard Guy Briggs <rgb@redhat.com>

Signed-off-by: William Roberts <wroberts@tresys.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3552717..01e7970 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1134,6 +1134,7 @@
 int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
+int get_cmdline(struct task_struct *task, char *buffer, int buflen);
 
 /* Is the vma a continuation of the stack vma above it? */
 static inline int vma_growsdown(struct vm_area_struct *vma, unsigned long addr)