Commit 7001510d authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

[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: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: default avatar"Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a9e88e84
...@@ -1151,7 +1151,6 @@ extern void exit_thread(void); ...@@ -1151,7 +1151,6 @@ extern void exit_thread(void);
extern void exit_files(struct task_struct *); extern void exit_files(struct task_struct *);
extern void exit_signal(struct task_struct *); extern void exit_signal(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_sighand(struct task_struct *);
extern void exit_itimers(struct signal_struct *); extern void exit_itimers(struct signal_struct *);
......
...@@ -1208,7 +1208,8 @@ static task_t *copy_process(unsigned long clone_flags, ...@@ -1208,7 +1208,8 @@ static task_t *copy_process(unsigned long clone_flags,
bad_fork_cleanup_signal: bad_fork_cleanup_signal:
exit_signal(p); exit_signal(p);
bad_fork_cleanup_sighand: bad_fork_cleanup_sighand:
exit_sighand(p); if (p->sighand)
__exit_sighand(p);
bad_fork_cleanup_fs: bad_fork_cleanup_fs:
exit_fs(p); /* blocking */ exit_fs(p); /* blocking */
bad_fork_cleanup_files: bad_fork_cleanup_files:
......
...@@ -336,20 +336,6 @@ void __exit_sighand(struct task_struct *tsk) ...@@ -336,20 +336,6 @@ void __exit_sighand(struct task_struct *tsk)
kmem_cache_free(sighand_cachep, sighand); 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. * This function expects the tasklist_lock write-locked.
*/ */
......
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