From 7001510d0cbf51ad202dd2d0744f54104285cbb9 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 28 Mar 2006 16:11:14 -0800 Subject: [PATCH] [PATCH] copy_process: cleanup bad_fork_cleanup_sighand The only caller of exit_sighand(tsk) is copy_process's error path. We can call __exit_sighand() directly and kill exit_sighand(). This 'tsk' was not yet registered in pid_hash[] or init_task.tasks, it has no external references, nobody can see it, and IF (clone_flags & CLONE_SIGHAND) At least 'current' has a reference to ->sighand, this means atomic_dec_and_test(sighand->count) can't be true. ELSE Nobody can see this ->sighand, this means we can free it without any locking. Signed-off-by: Oleg Nesterov Cc: "Eric W. Biederman" Acked-by: "Paul E. McKenney" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/sched.h | 1 - kernel/fork.c | 3 ++- kernel/signal.c | 14 -------------- 3 files changed, 2 insertions(+), 16 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index ca1fd31aae..69c2a1e152 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1151,7 +1151,6 @@ extern void exit_thread(void); extern void exit_files(struct task_struct *); extern void exit_signal(struct task_struct *); extern void __exit_signal(struct task_struct *); -extern void exit_sighand(struct task_struct *); extern void __exit_sighand(struct task_struct *); extern void exit_itimers(struct signal_struct *); diff --git a/kernel/fork.c b/kernel/fork.c index 33ffb5bf0d..8a46ad52be 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1208,7 +1208,8 @@ bad_fork_cleanup_mm: bad_fork_cleanup_signal: exit_signal(p); bad_fork_cleanup_sighand: - exit_sighand(p); + if (p->sighand) + __exit_sighand(p); bad_fork_cleanup_fs: exit_fs(p); /* blocking */ bad_fork_cleanup_files: diff --git a/kernel/signal.c b/kernel/signal.c index c5b65aa4c2..1d7f4463c3 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -336,20 +336,6 @@ void __exit_sighand(struct task_struct *tsk) kmem_cache_free(sighand_cachep, sighand); } -void exit_sighand(struct task_struct *tsk) -{ - write_lock_irq(&tasklist_lock); - rcu_read_lock(); - if (tsk->sighand != NULL) { - struct sighand_struct *sighand = rcu_dereference(tsk->sighand); - spin_lock(&sighand->siglock); - __exit_sighand(tsk); - spin_unlock(&sighand->siglock); - } - rcu_read_unlock(); - write_unlock_irq(&tasklist_lock); -} - /* * This function expects the tasklist_lock write-locked. */ -- 2.39.5