redo locking of tty->pgrp (47f86834) · Commits · 戴 / test

drivers/char/tty_io.c

+60 −18

Original line number	Diff line number	Diff line
		@@ -1204,26 +1204,37 @@ EXPORT_SYMBOL_GPL(tty_find_polling_driver);
		* not in the foreground, send a SIGTTOU. If the signal is blocked or
		* ignored, go ahead and perform the operation. (POSIX 7.2)
		*
		* Locking: none - FIXME: review this
		* Locking: ctrl_lock - FIXME: review this
		*/

		int tty_check_change(struct tty_struct *tty)
		{
		unsigned long flags;
		int ret = 0;

		if (current->signal->tty != tty)
		return 0;

		spin_lock_irqsave(&tty->ctrl_lock, flags);

		if (!tty->pgrp) {
		printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
		return 0;
		goto out;
		}
		if (task_pgrp(current) == tty->pgrp)
		return 0;
		goto out;
		if (is_ignored(SIGTTOU))
		return 0;
		if (is_current_pgrp_orphaned())
		return -EIO;
		goto out;
		if (is_current_pgrp_orphaned()) {
		ret = -EIO;
		goto out;
		}
		kill_pgrp(task_pgrp(current), SIGTTOU, 1);
		set_thread_flag(TIF_SIGPENDING);
		return -ERESTARTSYS;
		ret = -ERESTARTSYS;
		out:
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		return ret;
		}

		EXPORT_SYMBOL(tty_check_change);
		@@ -1403,6 +1414,7 @@ static void do_tty_hangup(struct work_struct *work)
		struct task_struct *p;
		struct tty_ldisc *ld;
		int closecount = 0, n;
		unsigned long flags;

		if (!tty)
		return;
		@@ -1479,19 +1491,24 @@ static void do_tty_hangup(struct work_struct *work)
		__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
		__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
		put_pid(p->signal->tty_old_pgrp); /* A noop */
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		if (tty->pgrp)
		p->signal->tty_old_pgrp = get_pid(tty->pgrp);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		spin_unlock_irq(&p->sighand->siglock);
		} while_each_pid_task(tty->session, PIDTYPE_SID, p);
		}
		read_unlock(&tasklist_lock);

		spin_lock_irqsave(&tty->ctrl_lock, flags);
		tty->flags = 0;
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = NULL;
		tty->pgrp = NULL;
		tty->ctrl_status = 0;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);

		/*
		* If one of the devices matches a console pointer, we
		* cannot just call hangup() because that will cause
		@@ -1666,10 +1683,13 @@ void disassociate_ctty(int on_exit)
		/* It is possible that do_tty_hangup has free'd this tty */
		tty = get_current_tty();
		if (tty) {
		unsigned long flags;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = NULL;
		tty->pgrp = NULL;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		} else {
		#ifdef TTY_DEBUG_HANGUP
		printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
		@@ -1785,10 +1805,8 @@ EXPORT_SYMBOL(start_tty);
		* for hung up devices before calling the line discipline method.
		*
		* Locking:
		* Locks the line discipline internally while needed
		* For historical reasons the line discipline read method is
		* invoked under the BKL. This will go away in time so do not rely on it
		* in new code. Multiple read calls may be outstanding in parallel.
		* Locks the line discipline internally while needed. Multiple
		* read calls may be outstanding in parallel.
		*/

		static ssize_t tty_read(struct file file, char __user buf, size_t count,
		@@ -2888,6 +2906,7 @@ static unsigned int tty_poll(struct file filp, poll_table wait)
		static int tty_fasync(int fd, struct file *filp, int on)
		{
		struct tty_struct *tty;
		unsigned long flags;
		int retval;

		tty = (struct tty_struct *)filp->private_data;
		@@ -2903,6 +2922,7 @@ static int tty_fasync(int fd, struct file *filp, int on)
		struct pid *pid;
		if (!waitqueue_active(&tty->read_wait))
		tty->minimum_to_wake = 1;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		if (tty->pgrp) {
		pid = tty->pgrp;
		type = PIDTYPE_PGID;
		@@ -2910,6 +2930,7 @@ static int tty_fasync(int fd, struct file *filp, int on)
		pid = task_pid(current);
		type = PIDTYPE_PID;
		}
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		retval = __f_setown(filp, pid, type, 0);
		if (retval)
		return retval;
		@@ -2995,6 +3016,8 @@ static int tiocswinsz(struct tty_struct tty, struct tty_struct real_tty,
		struct winsize __user *arg)
		{
		struct winsize tmp_ws;
		struct pid pgrp, rpgrp;
		unsigned long flags;

		if (copy_from_user(&tmp_ws, arg, sizeof(*arg)))
		return -EFAULT;
		@@ -3012,10 +3035,21 @@ static int tiocswinsz(struct tty_struct tty, struct tty_struct real_tty,
		}
		}
		#endif
		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);
		/* Get the PID values and reference them so we can
		avoid holding the tty ctrl lock while sending signals */
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		pgrp = get_pid(tty->pgrp);
		rpgrp = get_pid(real_tty->pgrp);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);

		if (pgrp)
		kill_pgrp(pgrp, SIGWINCH, 1);
		if (rpgrp != pgrp && rpgrp)
		kill_pgrp(rpgrp, SIGWINCH, 1);

		put_pid(pgrp);
		put_pid(rpgrp);

		tty->winsize = tmp_ws;
		real_tty->winsize = tmp_ws;
		done:
		@@ -3171,7 +3205,7 @@ static int tiocgpgrp(struct tty_struct tty, struct tty_struct real_tty, pid_t
		* Set the process group of the tty to the session passed. Only
		* permitted where the tty session is our session.
		*
		* Locking: RCU
		* Locking: RCU, ctrl lock
		*/

		static int tiocspgrp(struct tty_struct tty, struct tty_struct real_tty, pid_t __user *p)
		@@ -3179,6 +3213,7 @@ static int tiocspgrp(struct tty_struct tty, struct tty_struct real_tty, pid_t
		struct pid *pgrp;
		pid_t pgrp_nr;
		int retval = tty_check_change(real_tty);
		unsigned long flags;

		if (retval == -EIO)
		return -ENOTTY;
		@@ -3201,8 +3236,10 @@ static int tiocspgrp(struct tty_struct tty, struct tty_struct real_tty, pid_t
		if (session_of_pgrp(pgrp) != task_session(current))
		goto out_unlock;
		retval = 0;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		put_pid(real_tty->pgrp);
		real_tty->pgrp = get_pid(pgrp);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		out_unlock:
		rcu_read_unlock();
		return retval;
		@@ -4077,14 +4114,19 @@ void proc_clear_tty(struct task_struct *p)
		}
		EXPORT_SYMBOL(proc_clear_tty);

		/* Called under the sighand lock */

		static void __proc_set_tty(struct task_struct tsk, struct tty_struct tty)
		{
		if (tty) {
		/* We should not have a session or pgrp to here but.... */
		unsigned long flags;
		/* We should not have a session or pgrp to put here but.... */
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = get_pid(task_session(tsk));
		tty->pgrp = get_pid(task_pgrp(tsk));
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		tty->session = get_pid(task_session(tsk));
		}
		put_pid(tsk->signal->tty_old_pgrp);
		tsk->signal->tty = tty;

drivers/char/vt.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -909,15 +909,21 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines)

		if (vc->vc_tty) {
		struct winsize ws, *cws = &vc->vc_tty->winsize;
		unsigned long flags;

		memset(&ws, 0, sizeof(ws));
		ws.ws_row = vc->vc_rows;
		ws.ws_col = vc->vc_cols;
		ws.ws_ypixel = vc->vc_scan_lines;

		mutex_lock(&vc->vc_tty->termios_mutex);
		spin_lock_irqsave(&vc->vc_tty->ctrl_lock, flags);
		if ((ws.ws_row != cws->ws_row \|\| ws.ws_col != cws->ws_col) &&
		vc->vc_tty->pgrp)
		kill_pgrp(vc->vc_tty->pgrp, SIGWINCH, 1);
		spin_unlock_irqrestore(&vc->vc_tty->ctrl_lock, flags);
		*cws = ws;
		mutex_unlock(&vc->vc_tty->termios_mutex);
		}

		if (CON_IS_VISIBLE(vc))

include/linux/tty.h

+6 −4

Original line number	Diff line number	Diff line
		@@ -184,21 +184,22 @@ struct tty_struct {
		struct tty_ldisc ldisc;
		struct mutex termios_mutex;
		spinlock_t ctrl_lock;
		/* Termios values are protected by the termios mutex */
		struct ktermios termios, termios_locked;
		char name[64];
		struct pid *pgrp;
		struct pid pgrp; / Protected by ctrl lock */
		struct pid *session;
		unsigned long flags;
		int count;
		struct winsize winsize;
		struct winsize winsize; /* termios mutex */
		unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
		unsigned char low_latency:1, warned:1;
		unsigned char ctrl_status;
		unsigned char ctrl_status; /* ctrl_lock */
		unsigned int receive_room; /* Bytes free for queue */

		struct tty_struct *link;
		struct fasync_struct *fasync;
		struct tty_bufhead buf;
		struct tty_bufhead buf; /* Locked internally */
		int alt_speed; /* For magic substitution of 38400 bps */
		wait_queue_head_t write_wait;
		wait_queue_head_t read_wait;
		@@ -212,6 +213,7 @@ struct tty_struct {
		/*
		* The following is data for the N_TTY line discipline. For
		* historical reasons, this is included in the tty structure.
		* Mostly locked by the BKL.
		*/
		unsigned int column;
		unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;

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