[PATCH] tty: update the tty layer to work with struct pid
Of kernel subsystems that work with pids the tty layer is probably the largest
consumer. But it has the nice virtue that the assiation with a session only
lasts until the session leader exits. Which means that no reference counting
is required. So using struct pid winds up being a simple optimization to
avoid hash table lookups.
In the long term the use of pid_nr also ensures that when we have multiple pid
spaces mixed everything will work correctly.
Signed-off-by: Eric W. Biederman <eric@maxwell.lnxi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 94070f7..65672c5 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -155,7 +155,8 @@
unsigned int cmd, unsigned long arg);
static int tty_fasync(int fd, struct file * filp, int on);
static void release_tty(struct tty_struct *tty, int idx);
-static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
+static struct pid *__proc_set_tty(struct task_struct *tsk,
+ struct tty_struct *tty);
/**
* alloc_tty_struct - allocate a tty object
@@ -1110,17 +1111,17 @@
{
if (current->signal->tty != tty)
return 0;
- if (tty->pgrp <= 0) {
- printk(KERN_WARNING "tty_check_change: tty->pgrp <= 0!\n");
+ if (!tty->pgrp) {
+ printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
return 0;
}
- if (process_group(current) == tty->pgrp)
+ if (task_pgrp(current) == tty->pgrp)
return 0;
if (is_ignored(SIGTTOU))
return 0;
if (is_current_pgrp_orphaned())
return -EIO;
- (void) kill_pg(process_group(current), SIGTTOU, 1);
+ (void) kill_pgrp(task_pgrp(current), SIGTTOU, 1);
return -ERESTARTSYS;
}
@@ -1355,8 +1356,8 @@
tty_release is called */
read_lock(&tasklist_lock);
- if (tty->session > 0) {
- do_each_task_pid(tty->session, PIDTYPE_SID, p) {
+ if (tty->session) {
+ do_each_pid_task(tty->session, PIDTYPE_SID, p) {
spin_lock_irq(&p->sighand->siglock);
if (p->signal->tty == tty)
p->signal->tty = NULL;
@@ -1366,16 +1367,17 @@
}
__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
- if (tty->pgrp > 0)
- p->signal->tty_old_pgrp = tty->pgrp;
+ put_pid(p->signal->tty_old_pgrp); /* A noop */
+ if (tty->pgrp)
+ p->signal->tty_old_pgrp = get_pid(tty->pgrp);
spin_unlock_irq(&p->sighand->siglock);
- } while_each_task_pid(tty->session, PIDTYPE_SID, p);
+ } while_each_pid_task(tty->session, PIDTYPE_SID, p);
}
read_unlock(&tasklist_lock);
tty->flags = 0;
- tty->session = 0;
- tty->pgrp = -1;
+ tty->session = NULL;
+ tty->pgrp = NULL;
tty->ctrl_status = 0;
/*
* If one of the devices matches a console pointer, we
@@ -1460,12 +1462,12 @@
EXPORT_SYMBOL(tty_hung_up_p);
-static void session_clear_tty(pid_t session)
+static void session_clear_tty(struct pid *session)
{
struct task_struct *p;
- do_each_task_pid(session, PIDTYPE_SID, p) {
+ do_each_pid_task(session, PIDTYPE_SID, p) {
proc_clear_tty(p);
- } while_each_task_pid(session, PIDTYPE_SID, p);
+ } while_each_pid_task(session, PIDTYPE_SID, p);
}
/**
@@ -1495,48 +1497,54 @@
void disassociate_ctty(int on_exit)
{
struct tty_struct *tty;
- int tty_pgrp = -1;
+ struct pid *tty_pgrp = NULL;
lock_kernel();
mutex_lock(&tty_mutex);
tty = get_current_tty();
if (tty) {
- tty_pgrp = tty->pgrp;
+ tty_pgrp = get_pid(tty->pgrp);
mutex_unlock(&tty_mutex);
/* XXX: here we race, there is nothing protecting tty */
if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
tty_vhangup(tty);
} else if (on_exit) {
- pid_t old_pgrp;
+ struct pid *old_pgrp;
spin_lock_irq(¤t->sighand->siglock);
old_pgrp = current->signal->tty_old_pgrp;
- current->signal->tty_old_pgrp = 0;
+ current->signal->tty_old_pgrp = NULL;
spin_unlock_irq(¤t->sighand->siglock);
if (old_pgrp) {
- kill_pg(old_pgrp, SIGHUP, on_exit);
- kill_pg(old_pgrp, SIGCONT, on_exit);
+ kill_pgrp(old_pgrp, SIGHUP, on_exit);
+ kill_pgrp(old_pgrp, SIGCONT, on_exit);
+ put_pid(old_pgrp);
}
mutex_unlock(&tty_mutex);
unlock_kernel();
return;
}
- if (tty_pgrp > 0) {
- kill_pg(tty_pgrp, SIGHUP, on_exit);
+ if (tty_pgrp) {
+ kill_pgrp(tty_pgrp, SIGHUP, on_exit);
if (!on_exit)
- kill_pg(tty_pgrp, SIGCONT, on_exit);
+ kill_pgrp(tty_pgrp, SIGCONT, on_exit);
+ put_pid(tty_pgrp);
}
spin_lock_irq(¤t->sighand->siglock);
+ tty_pgrp = current->signal->tty_old_pgrp;
current->signal->tty_old_pgrp = 0;
spin_unlock_irq(¤t->sighand->siglock);
+ put_pid(tty_pgrp);
mutex_lock(&tty_mutex);
/* It is possible that do_tty_hangup has free'd this tty */
tty = get_current_tty();
if (tty) {
- tty->session = 0;
- tty->pgrp = 0;
+ put_pid(tty->session);
+ put_pid(tty->pgrp);
+ tty->session = NULL;
+ tty->pgrp = NULL;
} else {
#ifdef TTY_DEBUG_HANGUP
printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
@@ -1547,7 +1555,7 @@
/* Now clear signal->tty under the lock */
read_lock(&tasklist_lock);
- session_clear_tty(process_session(current));
+ session_clear_tty(task_session(current));
read_unlock(&tasklist_lock);
unlock_kernel();
}
@@ -2484,6 +2492,7 @@
int index;
dev_t device = inode->i_rdev;
unsigned short saved_flags = filp->f_flags;
+ struct pid *old_pgrp;
nonseekable_open(inode, filp);
@@ -2577,15 +2586,17 @@
goto retry_open;
}
+ old_pgrp = NULL;
mutex_lock(&tty_mutex);
spin_lock_irq(¤t->sighand->siglock);
if (!noctty &&
current->signal->leader &&
!current->signal->tty &&
- tty->session == 0)
- __proc_set_tty(current, tty);
+ tty->session == NULL)
+ old_pgrp = __proc_set_tty(current, tty);
spin_unlock_irq(¤t->sighand->siglock);
mutex_unlock(&tty_mutex);
+ put_pid(old_pgrp);
return 0;
}
@@ -2724,9 +2735,18 @@
return retval;
if (on) {
+ enum pid_type type;
+ struct pid *pid;
if (!waitqueue_active(&tty->read_wait))
tty->minimum_to_wake = 1;
- retval = f_setown(filp, (-tty->pgrp) ? : current->pid, 0);
+ if (tty->pgrp) {
+ pid = tty->pgrp;
+ type = PIDTYPE_PGID;
+ } else {
+ pid = task_pid(current);
+ type = PIDTYPE_PID;
+ }
+ retval = __f_setown(filp, pid, type, 0);
if (retval)
return retval;
} else {
@@ -2828,10 +2848,10 @@
}
}
#endif
- if (tty->pgrp > 0)
- kill_pg(tty->pgrp, SIGWINCH, 1);
- if ((real_tty->pgrp != tty->pgrp) && (real_tty->pgrp > 0))
- kill_pg(real_tty->pgrp, SIGWINCH, 1);
+ if (tty->pgrp)
+ kill_pgrp(tty->pgrp, SIGWINCH, 1);
+ if ((real_tty->pgrp != tty->pgrp) && real_tty->pgrp)
+ kill_pgrp(real_tty->pgrp, SIGWINCH, 1);
tty->winsize = tmp_ws;
real_tty->winsize = tmp_ws;
done:
@@ -2916,8 +2936,7 @@
static int tiocsctty(struct tty_struct *tty, int arg)
{
int ret = 0;
- if (current->signal->leader &&
- (process_session(current) == tty->session))
+ if (current->signal->leader && (task_session(current) == tty->session))
return ret;
mutex_lock(&tty_mutex);
@@ -2930,7 +2949,7 @@
goto unlock;
}
- if (tty->session > 0) {
+ if (tty->session) {
/*
* This tty is already the controlling
* tty for another session group!
@@ -2973,7 +2992,7 @@
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
- return put_user(real_tty->pgrp, p);
+ return put_user(pid_nr(real_tty->pgrp), p);
}
/**
@@ -3000,7 +3019,7 @@
return retval;
if (!current->signal->tty ||
(current->signal->tty != real_tty) ||
- (real_tty->session != process_session(current)))
+ (real_tty->session != task_session(current)))
return -ENOTTY;
if (get_user(pgrp_nr, p))
return -EFAULT;
@@ -3015,7 +3034,8 @@
if (session_of_pgrp(pgrp) != task_session(current))
goto out_unlock;
retval = 0;
- real_tty->pgrp = pgrp_nr;
+ put_pid(real_tty->pgrp);
+ real_tty->pgrp = get_pid(pgrp);
out_unlock:
rcu_read_unlock();
return retval;
@@ -3041,9 +3061,9 @@
*/
if (tty == real_tty && current->signal->tty != real_tty)
return -ENOTTY;
- if (real_tty->session <= 0)
+ if (!real_tty->session)
return -ENOTTY;
- return put_user(real_tty->session, p);
+ return put_user(pid_nr(real_tty->session), p);
}
/**
@@ -3343,7 +3363,7 @@
tty_hangup(tty);
#else
struct task_struct *g, *p;
- int session;
+ struct pid *session;
int i;
struct file *filp;
struct fdtable *fdt;
@@ -3359,12 +3379,12 @@
read_lock(&tasklist_lock);
/* Kill the entire session */
- do_each_task_pid(session, PIDTYPE_SID, p) {
+ do_each_pid_task(session, PIDTYPE_SID, p) {
printk(KERN_NOTICE "SAK: killed process %d"
" (%s): process_session(p)==tty->session\n",
p->pid, p->comm);
send_sig(SIGKILL, p, 1);
- } while_each_task_pid(session, PIDTYPE_SID, p);
+ } while_each_pid_task(session, PIDTYPE_SID, p);
/* Now kill any processes that happen to have the
* tty open.
*/
@@ -3533,7 +3553,8 @@
memset(tty, 0, sizeof(struct tty_struct));
tty->magic = TTY_MAGIC;
tty_ldisc_assign(tty, tty_ldisc_get(N_TTY));
- tty->pgrp = -1;
+ tty->session = NULL;
+ tty->pgrp = NULL;
tty->overrun_time = jiffies;
tty->buf.head = tty->buf.tail = NULL;
tty_buffer_init(tty);
@@ -3804,21 +3825,28 @@
}
EXPORT_SYMBOL(proc_clear_tty);
-static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
+static struct pid *__proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
{
+ struct pid *old_pgrp;
if (tty) {
- tty->session = process_session(tsk);
- tty->pgrp = process_group(tsk);
+ tty->session = get_pid(task_session(tsk));
+ tty->pgrp = get_pid(task_pgrp(tsk));
}
+ old_pgrp = tsk->signal->tty_old_pgrp;
tsk->signal->tty = tty;
- tsk->signal->tty_old_pgrp = 0;
+ tsk->signal->tty_old_pgrp = NULL;
+ return old_pgrp;
}
void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
{
+ struct pid *old_pgrp;
+
spin_lock_irq(&tsk->sighand->siglock);
- __proc_set_tty(tsk, tty);
+ old_pgrp = __proc_set_tty(tsk, tty);
spin_unlock_irq(&tsk->sighand->siglock);
+
+ put_pid(old_pgrp);
}
struct tty_struct *get_current_tty(void)