[PATCH] Decrease number of pointer derefs in exit.c

Decrease the number of pointer derefs in kernel/exit.c

Benefits of the patch:
 - Fewer pointer dereferences should make the code slightly faster.
 - Size of generated code is smaller
 - improved readability

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/exit.c b/kernel/exit.c
index e75a51f..8027228 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1071,6 +1071,9 @@ static int wait_task_zombie(task_t *p, int noreap,
        }
 
        if (likely(p->real_parent == p->parent) && likely(p->signal)) {
+               struct signal_struct *psig;
+               struct signal_struct *sig;
+
                /*
                 * The resource counters for the group leader are in its
                 * own task_struct.  Those for dead threads in the group
@@ -1087,24 +1090,26 @@ static int wait_task_zombie(task_t *p, int noreap,
                 * here reaping other children at the same time.
                 */
                spin_lock_irq(&p->parent->sighand->siglock);
-               p->parent->signal->cutime =
-                       cputime_add(p->parent->signal->cutime,
+               psig = p->parent->signal;
+               sig = p->signal;
+               psig->cutime =
+                       cputime_add(psig->cutime,
                        cputime_add(p->utime,
-                       cputime_add(p->signal->utime,
-                                   p->signal->cutime)));
-               p->parent->signal->cstime =
-                       cputime_add(p->parent->signal->cstime,
+                       cputime_add(sig->utime,
+                                   sig->cutime)));
+               psig->cstime =
+                       cputime_add(psig->cstime,
                        cputime_add(p->stime,
-                       cputime_add(p->signal->stime,
-                                   p->signal->cstime)));
-               p->parent->signal->cmin_flt +=
-                       p->min_flt + p->signal->min_flt + p->signal->cmin_flt;
-               p->parent->signal->cmaj_flt +=
-                       p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt;
-               p->parent->signal->cnvcsw +=
-                       p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw;
-               p->parent->signal->cnivcsw +=
-                       p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw;
+                       cputime_add(sig->stime,
+                                   sig->cstime)));
+               psig->cmin_flt +=
+                       p->min_flt + sig->min_flt + sig->cmin_flt;
+               psig->cmaj_flt +=
+                       p->maj_flt + sig->maj_flt + sig->cmaj_flt;
+               psig->cnvcsw +=
+                       p->nvcsw + sig->nvcsw + sig->cnvcsw;
+               psig->cnivcsw +=
+                       p->nivcsw + sig->nivcsw + sig->cnivcsw;
                spin_unlock_irq(&p->parent->sighand->siglock);
        }