2007-08-23 13:28:14

by Alexey Dobriyan

Subject: [PATCH] Shrink task_struct if CONFIG_FUTEX=n

robust_list, compat_robust_list, pi_state_list, pi_state_cache are
really used if futexes are on.

Signed-off-by: Alexey Dobriyan <[email protected]>
---

include/linux/sched.h | 3 ++-
kernel/exit.c | 6 +++++-
kernel/fork.c | 3 ++-
3 files changed, 9 insertions(+), 3 deletions(-)

--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1174,13 +1174,14 @@ struct task_struct {
int cpuset_mems_generation;
int cpuset_mem_spread_rotor;
#endif
+#ifdef CONFIG_FUTEX
struct robust_list_head __user *robust_list;
#ifdef CONFIG_COMPAT
struct compat_robust_list_head __user *compat_robust_list;
#endif
struct list_head pi_state_list;
struct futex_pi_state *pi_state_cache;
-
+#endif
atomic_t fs_excl; /* holding fs exclusive resources */
struct rcu_head rcu;

--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -964,12 +964,14 @@ fastcall NORET_TYPE void do_exit(long code)
exit_itimers(tsk->signal);
}
acct_collect(code, group_dead);
+#ifdef CONFIG_FUTEX
if (unlikely(tsk->robust_list))
exit_robust_list(tsk);
-#if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
+#ifdef CONFIG_COMPAT
if (unlikely(tsk->compat_robust_list))
compat_exit_robust_list(tsk);
#endif
+#endif
if (group_dead)
tty_audit_exit();
if (unlikely(tsk->audit_context))
@@ -1004,6 +1006,7 @@ fastcall NORET_TYPE void do_exit(long code)
mpol_free(tsk->mempolicy);
tsk->mempolicy = NULL;
#endif
+#ifdef CONFIG_FUTEX
/*
* This must happen late, after the PID is not
* hashed anymore:
@@ -1012,6 +1015,7 @@ fastcall NORET_TYPE void do_exit(long code)
exit_pi_state_list(tsk);
if (unlikely(current->pi_state_cache))
kfree(current->pi_state_cache);
+#endif
/*
* Make sure we are holding no locks:
*/
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1143,13 +1143,14 @@ static struct task_struct *copy_process(unsigned long clone_flags,
* Clear TID on mm_release()?
*/
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
+#ifdef CONFIG_FUTEX
p->robust_list = NULL;
#ifdef CONFIG_COMPAT
p->compat_robust_list = NULL;
#endif
INIT_LIST_HEAD(&p->pi_state_list);
p->pi_state_cache = NULL;
-
+#endif
/*
* sigaltstack should be cleared when sharing the same VM
*/

2007-08-23 13:54:29

by Ingo Molnar

Subject: Re: [PATCH] Shrink task_struct if CONFIG_FUTEX=n

* Alexey Dobriyan <[email protected]> wrote:

> robust_list, compat_robust_list, pi_state_list, pi_state_cache are
> really used if futexes are on.
>
> Signed-off-by: Alexey Dobriyan <[email protected]>

looks good to me.

Acked-by: Ingo Molnar <[email protected]>

Ingo