Messages in this thread Patch in this message | | | Date | Thu, 18 Mar 2010 23:37:36 +0100 | From | Oleg Nesterov <> | Subject | [PATCH] move tty_kref_put() outside of __cleanup_signal() |
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tty_kref_put() have two callsites in copy_process() pathes,
1. if copy_process() suceeds it is called before we copy signal->tty from parent
2. otherwise it is called from __cleanup_signal() under bad_fork_cleanup_signal: label
In both cases tty_kref_put() is not right and unneeded because we don't have the balancing tty_kref_get(). Fortunately, this is harmless because this can only happen without CLONE_THREAD, and in this case signal->tty must be NULL.
Remove tty_kref_put() from copy_process() and __cleanup_signal(), and change another caller of __cleanup_signal(), __exit_signal(), to call tty_kref_put() by hand.
I hope this change makes sense by itself, but it is also needed to make ->signal refcountable.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> ---
kernel/fork.c | 2 -- kernel/exit.c | 1 + 2 files changed, 1 insertion(+), 2 deletions(-)
--- 34-rc1/kernel/fork.c~7_TTY_PUT 2010-03-17 16:04:22.000000000 +0100 +++ 34-rc1/kernel/fork.c 2010-03-18 22:45:14.000000000 +0100 @@ -896,7 +896,6 @@ static int copy_signal(unsigned long clo void __cleanup_signal(struct signal_struct *sig) { thread_group_cputime_free(sig); - tty_kref_put(sig->tty); kmem_cache_free(signal_cachep, sig); } @@ -1264,7 +1263,6 @@ static struct task_struct *copy_process( p->nsproxy->pid_ns->child_reaper = p; p->signal->leader_pid = pid; - tty_kref_put(p->signal->tty); p->signal->tty = tty_kref_get(current->signal->tty); attach_pid(p, PIDTYPE_PGID, task_pgrp(current)); attach_pid(p, PIDTYPE_SID, task_session(current)); --- 34-rc1/kernel/exit.c~7_TTY_PUT 2010-03-17 20:05:38.000000000 +0100 +++ 34-rc1/kernel/exit.c 2010-03-18 22:46:41.000000000 +0100 @@ -150,6 +150,7 @@ static void __exit_signal(struct task_st * see account_group_exec_runtime(). */ task_rq_unlock_wait(tsk); + tty_kref_put(sig->tty); __cleanup_signal(sig); } }
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