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tty: Add a kref count

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Introduce a kref to the tty structure and use it to protect the tty->signal
tty references. For now we don't introduce it for anything else.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox
2008-10-13 10:37:26 +01:00
committed by Linus Torvalds
parent 348eb12e55
commit 9c9f4ded90
4 changed files with 71 additions and 10 deletions
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5
kernel/fork.c
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@ -802,6 +802,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
sig->leader = 0; /* session leadership doesn't inherit */
sig->tty_old_pgrp = NULL;
sig->tty = NULL;
sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
sig->gtime = cputime_zero;
@ -838,6 +839,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
void __cleanup_signal(struct signal_struct *sig)
{
exit_thread_group_keys(sig);
tty_kref_put(sig->tty);
kmem_cache_free(signal_cachep, sig);
}
@ -1227,7 +1229,8 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->nsproxy->pid_ns->child_reaper = p;
p->signal->leader_pid = pid;
p->signal->tty = current->signal->tty;
tty_kref_put(p->signal->tty);
p->signal->tty = tty_kref_get(current->signal->tty);
set_task_pgrp(p, task_pgrp_nr(current));
set_task_session(p, task_session_nr(current));
attach_pid(p, PIDTYPE_PGID, task_pgrp(current));

4
kernel/sys.c
View File

@ -1060,9 +1060,7 @@ asmlinkage long sys_setsid(void)
group_leader->signal->leader = 1;
__set_special_pids(sid);
spin_lock(&group_leader->sighand->siglock);
group_leader->signal->tty = NULL;
spin_unlock(&group_leader->sighand->siglock);
proc_clear_tty(group_leader);
err = session;
out: