diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/tty_io.c | 237 | ||||
| -rw-r--r-- | drivers/s390/char/fs3270.c | 12 |
2 files changed, 149 insertions, 100 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index b3cfc8bc613c..0c856a6f3677 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -126,7 +126,7 @@ EXPORT_SYMBOL(tty_std_termios); LIST_HEAD(tty_drivers); /* linked list of tty drivers */ -/* Semaphore to protect creating and releasing a tty. This is shared with +/* Mutex to protect creating and releasing a tty. This is shared with vt.c for deeply disgusting hack reasons */ DEFINE_MUTEX(tty_mutex); EXPORT_SYMBOL(tty_mutex); @@ -250,7 +250,7 @@ static int check_tty_count(struct tty_struct *tty, const char *routine) "!= #fd's(%d) in %s\n", tty->name, tty->count, count, routine); return count; - } + } #endif return 0; } @@ -259,18 +259,6 @@ static int check_tty_count(struct tty_struct *tty, const char *routine) * Tty buffer allocation management */ - -/** - * tty_buffer_free_all - free buffers used by a tty - * @tty: tty to free from - * - * Remove all the buffers pending on a tty whether queued with data - * or in the free ring. Must be called when the tty is no longer in use - * - * Locking: none - */ - - /** * tty_buffer_free_all - free buffers used by a tty * @tty: tty to free from @@ -614,7 +602,7 @@ EXPORT_SYMBOL_GPL(tty_prepare_flip_string_flags); * they are not on hot paths so a little discipline won't do * any harm. * - * Locking: takes termios_sem + * Locking: takes termios_mutex */ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) @@ -915,7 +903,7 @@ static void tty_ldisc_enable(struct tty_struct *tty) * context. * * Locking: takes tty_ldisc_lock. - * called functions take termios_sem + * called functions take termios_mutex */ static int tty_set_ldisc(struct tty_struct *tty, int ldisc) @@ -1267,12 +1255,12 @@ EXPORT_SYMBOL_GPL(tty_ldisc_flush); * * Locking: * BKL - * redirect lock for undoing redirection - * file list lock for manipulating list of ttys - * tty_ldisc_lock from called functions - * termios_sem resetting termios data - * tasklist_lock to walk task list for hangup event - * + * redirect lock for undoing redirection + * file list lock for manipulating list of ttys + * tty_ldisc_lock from called functions + * termios_mutex resetting termios data + * tasklist_lock to walk task list for hangup event + * ->siglock to protect ->signal/->sighand */ static void do_tty_hangup(struct work_struct *work) { @@ -1354,14 +1342,18 @@ static void do_tty_hangup(struct work_struct *work) read_lock(&tasklist_lock); if (tty->session > 0) { do_each_task_pid(tty->session, PIDTYPE_SID, p) { + spin_lock_irq(&p->sighand->siglock); if (p->signal->tty == tty) p->signal->tty = NULL; - if (!p->signal->leader) + if (!p->signal->leader) { + spin_unlock_irq(&p->sighand->siglock); continue; - group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p); - group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p); + } + __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; + spin_unlock_irq(&p->sighand->siglock); } while_each_task_pid(tty->session, PIDTYPE_SID, p); } read_unlock(&tasklist_lock); @@ -1453,6 +1445,14 @@ int tty_hung_up_p(struct file * filp) EXPORT_SYMBOL(tty_hung_up_p); +static void session_clear_tty(pid_t session) +{ + struct task_struct *p; + do_each_task_pid(session, PIDTYPE_SID, p) { + proc_clear_tty(p); + } while_each_task_pid(session, PIDTYPE_SID, p); +} + /** * disassociate_ctty - disconnect controlling tty * @on_exit: true if exiting so need to "hang up" the session @@ -1469,31 +1469,35 @@ EXPORT_SYMBOL(tty_hung_up_p); * The argument on_exit is set to 1 if called when a process is * exiting; it is 0 if called by the ioctl TIOCNOTTY. * - * Locking: tty_mutex is taken to protect current->signal->tty + * Locking: * BKL is taken for hysterical raisins - * Tasklist lock is taken (under tty_mutex) to walk process - * lists for the session. + * tty_mutex is taken to protect tty + * ->siglock is taken to protect ->signal/->sighand + * tasklist_lock is taken to walk process list for sessions + * ->siglock is taken to protect ->signal/->sighand */ void disassociate_ctty(int on_exit) { struct tty_struct *tty; - struct task_struct *p; int tty_pgrp = -1; + int session; lock_kernel(); mutex_lock(&tty_mutex); - tty = current->signal->tty; + tty = get_current_tty(); if (tty) { tty_pgrp = 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 (current->signal->tty_old_pgrp) { - kill_pg(current->signal->tty_old_pgrp, SIGHUP, on_exit); - kill_pg(current->signal->tty_old_pgrp, SIGCONT, on_exit); + pid_t old_pgrp = current->signal->tty_old_pgrp; + if (old_pgrp) { + kill_pg(old_pgrp, SIGHUP, on_exit); + kill_pg(old_pgrp, SIGCONT, on_exit); } mutex_unlock(&tty_mutex); unlock_kernel(); @@ -1505,19 +1509,29 @@ void disassociate_ctty(int on_exit) kill_pg(tty_pgrp, SIGCONT, on_exit); } - /* Must lock changes to tty_old_pgrp */ - mutex_lock(&tty_mutex); + spin_lock_irq(¤t->sighand->siglock); current->signal->tty_old_pgrp = 0; - tty->session = 0; - tty->pgrp = -1; + session = current->signal->session; + spin_unlock_irq(¤t->sighand->siglock); + + 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; + } else { +#ifdef TTY_DEBUG_HANGUP + printk(KERN_DEBUG "error attempted to write to tty [0x%p]" + " = NULL", tty); +#endif + } + mutex_unlock(&tty_mutex); /* Now clear signal->tty under the lock */ read_lock(&tasklist_lock); - do_each_task_pid(current->signal->session, PIDTYPE_SID, p) { - p->signal->tty = NULL; - } while_each_task_pid(current->signal->session, PIDTYPE_SID, p); + session_clear_tty(session); read_unlock(&tasklist_lock); - mutex_unlock(&tty_mutex); unlock_kernel(); } @@ -2337,16 +2351,10 @@ static void release_dev(struct file * filp) * tty. */ if (tty_closing || o_tty_closing) { - struct task_struct *p; - read_lock(&tasklist_lock); - do_each_task_pid(tty->session, PIDTYPE_SID, p) { - p->signal->tty = NULL; - } while_each_task_pid(tty->session, PIDTYPE_SID, p); + session_clear_tty(tty->session); if (o_tty) - do_each_task_pid(o_tty->session, PIDTYPE_SID, p) { - p->signal->tty = NULL; - } while_each_task_pid(o_tty->session, PIDTYPE_SID, p); + session_clear_tty(o_tty->session); read_unlock(&tasklist_lock); } @@ -2443,9 +2451,9 @@ static void release_dev(struct file * filp) * The termios state of a pty is reset on first open so that * settings don't persist across reuse. * - * Locking: tty_mutex protects current->signal->tty, get_tty_driver and - * init_dev work. tty->count should protect the rest. - * task_lock is held to update task details for sessions + * Locking: tty_mutex protects tty, get_tty_driver and init_dev work. + * tty->count should protect the rest. + * ->siglock protects ->signal/->sighand */ static int tty_open(struct inode * inode, struct file * filp) @@ -2467,12 +2475,13 @@ retry_open: mutex_lock(&tty_mutex); if (device == MKDEV(TTYAUX_MAJOR,0)) { - if (!current->signal->tty) { + tty = get_current_tty(); + if (!tty) { mutex_unlock(&tty_mutex); return -ENXIO; } - driver = current->signal->tty->driver; - index = current->signal->tty->index; + driver = tty->driver; + index = tty->index; filp->f_flags |= O_NONBLOCK; /* Don't let /dev/tty block */ /* noctty = 1; */ goto got_driver; @@ -2547,17 +2556,16 @@ got_driver: filp->f_op = &tty_fops; goto retry_open; } + + mutex_lock(&tty_mutex); + spin_lock_irq(¤t->sighand->siglock); if (!noctty && current->signal->leader && !current->signal->tty && - tty->session == 0) { - task_lock(current); - current->signal->tty = tty; - task_unlock(current); - current->signal->tty_old_pgrp = 0; - tty->session = current->signal->session; - tty->pgrp = process_group(current); - } + tty->session == 0) + __proc_set_tty(current, tty); + spin_unlock_irq(¤t->sighand->siglock); + mutex_unlock(&tty_mutex); return 0; } @@ -2747,7 +2755,7 @@ static int tiocsti(struct tty_struct *tty, char __user *p) * * Copies the kernel idea of the window size into the user buffer. * - * Locking: tty->termios_sem is taken to ensure the winsize data + * Locking: tty->termios_mutex is taken to ensure the winsize data * is consistent. */ @@ -2774,8 +2782,8 @@ static int tiocgwinsz(struct tty_struct *tty, struct winsize __user * arg) * Locking: * Called function use the console_sem is used to ensure we do * not try and resize the console twice at once. - * The tty->termios_sem is used to ensure we don't double - * resize and get confused. Lock order - tty->termios.sem before + * The tty->termios_mutex is used to ensure we don't double + * resize and get confused. Lock order - tty->termios_mutex before * console sem */ @@ -2880,25 +2888,28 @@ static int fionbio(struct file *file, int __user *p) * leader to set this tty as the controlling tty for the session. * * Locking: - * Takes tasklist lock internally to walk sessions - * Takes task_lock() when updating signal->tty * Takes tty_mutex() to protect tty instance - * + * Takes tasklist_lock internally to walk sessions + * Takes ->siglock() when updating signal->tty */ static int tiocsctty(struct tty_struct *tty, int arg) { - struct task_struct *p; - + int ret = 0; if (current->signal->leader && (current->signal->session == tty->session)) - return 0; + return ret; + + mutex_lock(&tty_mutex); /* * The process must be a session leader and * not have a controlling tty already. */ - if (!current->signal->leader || current->signal->tty) - return -EPERM; + if (!current->signal->leader || current->signal->tty) { + ret = -EPERM; + goto unlock; + } + if (tty->session > 0) { /* * This tty is already the controlling @@ -2908,24 +2919,18 @@ static int tiocsctty(struct tty_struct *tty, int arg) /* * Steal it away */ - read_lock(&tasklist_lock); - do_each_task_pid(tty->session, PIDTYPE_SID, p) { - p->signal->tty = NULL; - } while_each_task_pid(tty->session, PIDTYPE_SID, p); + session_clear_tty(tty->session); read_unlock(&tasklist_lock); - } else - return -EPERM; + } else { + ret = -EPERM; + goto unlock; + } } - mutex_lock(&tty_mutex); - task_lock(current); - current->signal->tty = tty; - task_unlock(current); + proc_set_tty(current, tty); +unlock: mutex_unlock(&tty_mutex); - current->signal->tty_old_pgrp = 0; - tty->session = current->signal->session; - tty->pgrp = process_group(current); - return 0; + return ret; } /** @@ -2937,7 +2942,7 @@ static int tiocsctty(struct tty_struct *tty, int arg) * Obtain the process group of the tty. If there is no process group * return an error. * - * Locking: none. Reference to ->signal->tty is safe. + * Locking: none. Reference to current->signal->tty is safe. */ static int tiocgpgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) @@ -2995,7 +3000,7 @@ static int tiocspgrp(struct tty_struct *tty, struct tty_struct *real_tty, pid_t * Obtain the session id of the tty. If there is no session * return an error. * - * Locking: none. Reference to ->signal->tty is safe. + * Locking: none. Reference to current->signal->tty is safe. */ static int tiocgsid(struct tty_struct *tty, struct tty_struct *real_tty, pid_t __user *p) @@ -3214,14 +3219,11 @@ int tty_ioctl(struct inode * inode, struct file * file, clear_bit(TTY_EXCLUSIVE, &tty->flags); return 0; case TIOCNOTTY: - /* FIXME: taks lock or tty_mutex ? */ if (current->signal->tty != tty) return -ENOTTY; if (current->signal->leader) disassociate_ctty(0); - task_lock(current); - current->signal->tty = NULL; - task_unlock(current); + proc_clear_tty(current); return 0; case TIOCSCTTY: return tiocsctty(tty, arg); @@ -3321,7 +3323,7 @@ static void __do_SAK(struct work_struct *work) if (!tty) return; - session = tty->session; + session = tty->session; /* We don't want an ldisc switch during this */ disc = tty_ldisc_ref(tty); @@ -3834,9 +3836,52 @@ int tty_unregister_driver(struct tty_driver *driver) cdev_del(&driver->cdev); return 0; } - EXPORT_SYMBOL(tty_unregister_driver); +dev_t tty_devnum(struct tty_struct *tty) +{ + return MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index; +} +EXPORT_SYMBOL(tty_devnum); + +void proc_clear_tty(struct task_struct *p) +{ + spin_lock_irq(&p->sighand->siglock); + p->signal->tty = NULL; + spin_unlock_irq(&p->sighand->siglock); +} +EXPORT_SYMBOL(proc_clear_tty); + +void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) +{ + if (tty) { + tty->session = tsk->signal->session; + tty->pgrp = process_group(tsk); + } + tsk->signal->tty = tty; + tsk->signal->tty_old_pgrp = 0; +} + +void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty) +{ + spin_lock_irq(&tsk->sighand->siglock); + __proc_set_tty(tsk, tty); + spin_unlock_irq(&tsk->sighand->siglock); +} + +struct tty_struct *get_current_tty(void) +{ + struct tty_struct *tty; + WARN_ON_ONCE(!mutex_is_locked(&tty_mutex)); + tty = current->signal->tty; + /* + * session->tty can be changed/cleared from under us, make sure we + * issue the load. The obtained pointer, when not NULL, is valid as + * long as we hold tty_mutex. + */ + barrier(); + return tty; +} /* * Initialize the console device. This is called *early*, so diff --git a/drivers/s390/char/fs3270.c b/drivers/s390/char/fs3270.c index 78f8bda81dae..ef205ddd31a4 100644 --- a/drivers/s390/char/fs3270.c +++ b/drivers/s390/char/fs3270.c @@ -424,11 +424,15 @@ fs3270_open(struct inode *inode, struct file *filp) minor = iminor(filp->f_dentry->d_inode); /* Check for minor 0 multiplexer. */ if (minor == 0) { - if (!current->signal->tty) + struct tty_struct *tty; + mutex_lock(&tty_mutex); + tty = get_current_tty(); + if (!tty || tty->driver->major != IBM_TTY3270_MAJOR) { + mutex_unlock(&tty_mutex); return -ENODEV; - if (current->signal->tty->driver->major != IBM_TTY3270_MAJOR) - return -ENODEV; - minor = current->signal->tty->index + RAW3270_FIRSTMINOR; + } + minor = tty->index + RAW3270_FIRSTMINOR; + mutex_unlock(&tty_mutex); } /* Check if some other program is already using fullscreen mode. */ fp = (struct fs3270 *) raw3270_find_view(&fs3270_fn, minor); |