diff options
author | James Bottomley <James.Bottomley@HansenPartnership.com> | 2009-06-12 10:02:03 -0500 |
---|---|---|
committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2009-06-12 10:02:03 -0500 |
commit | 82681a318f9f028ea64e61f24bbd9ac535531921 (patch) | |
tree | 529b6a5b4fd040fb54b7672b1a224ebd47445876 /drivers/char/tty_ldisc.c | |
parent | 3860c97bd60a4525bb62eb90e3e7d2f02662ac59 (diff) | |
parent | 8ebf975608aaebd7feb33d77f07ba21a6380e086 (diff) |
[SCSI] Merge branch 'linus'
Conflicts:
drivers/message/fusion/mptsas.c
fixed up conflict between req->data_len accessors and mptsas driver updates.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'drivers/char/tty_ldisc.c')
-rw-r--r-- | drivers/char/tty_ldisc.c | 549 |
1 files changed, 360 insertions, 189 deletions
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c index f78f5b0127a..39c8f86dedd 100644 --- a/drivers/char/tty_ldisc.c +++ b/drivers/char/tty_ldisc.c @@ -115,19 +115,22 @@ EXPORT_SYMBOL(tty_unregister_ldisc); /** * tty_ldisc_try_get - try and reference an ldisc * @disc: ldisc number - * @ld: tty ldisc structure to complete * * Attempt to open and lock a line discipline into place. Return - * the line discipline refcounted and assigned in ld. On an error - * report the error code back + * the line discipline refcounted or an error. */ -static int tty_ldisc_try_get(int disc, struct tty_ldisc *ld) +static struct tty_ldisc *tty_ldisc_try_get(int disc) { unsigned long flags; + struct tty_ldisc *ld; struct tty_ldisc_ops *ldops; int err = -EINVAL; - + + ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL); + if (ld == NULL) + return ERR_PTR(-ENOMEM); + spin_lock_irqsave(&tty_ldisc_lock, flags); ld->ops = NULL; ldops = tty_ldiscs[disc]; @@ -140,17 +143,19 @@ static int tty_ldisc_try_get(int disc, struct tty_ldisc *ld) /* lock it */ ldops->refcount++; ld->ops = ldops; + ld->refcount = 0; err = 0; } } spin_unlock_irqrestore(&tty_ldisc_lock, flags); - return err; + if (err) + return ERR_PTR(err); + return ld; } /** * tty_ldisc_get - take a reference to an ldisc * @disc: ldisc number - * @ld: tty line discipline structure to use * * Takes a reference to a line discipline. Deals with refcounts and * module locking counts. Returns NULL if the discipline is not available. @@ -161,52 +166,54 @@ static int tty_ldisc_try_get(int disc, struct tty_ldisc *ld) * takes tty_ldisc_lock to guard against ldisc races */ -static int tty_ldisc_get(int disc, struct tty_ldisc *ld) +static struct tty_ldisc *tty_ldisc_get(int disc) { - int err; + struct tty_ldisc *ld; if (disc < N_TTY || disc >= NR_LDISCS) - return -EINVAL; - err = tty_ldisc_try_get(disc, ld); - if (err < 0) { + return ERR_PTR(-EINVAL); + ld = tty_ldisc_try_get(disc); + if (IS_ERR(ld)) { request_module("tty-ldisc-%d", disc); - err = tty_ldisc_try_get(disc, ld); + ld = tty_ldisc_try_get(disc); } - return err; + return ld; } /** * tty_ldisc_put - drop ldisc reference - * @disc: ldisc number + * @ld: ldisc * * Drop a reference to a line discipline. Manage refcounts and - * module usage counts + * module usage counts. Free the ldisc once the recount hits zero. * * Locking: * takes tty_ldisc_lock to guard against ldisc races */ -static void tty_ldisc_put(struct tty_ldisc_ops *ld) +static void tty_ldisc_put(struct tty_ldisc *ld) { unsigned long flags; - int disc = ld->num; + int disc = ld->ops->num; + struct tty_ldisc_ops *ldo; BUG_ON(disc < N_TTY || disc >= NR_LDISCS); spin_lock_irqsave(&tty_ldisc_lock, flags); - ld = tty_ldiscs[disc]; - BUG_ON(ld->refcount == 0); - ld->refcount--; - module_put(ld->owner); + ldo = tty_ldiscs[disc]; + BUG_ON(ldo->refcount == 0); + ldo->refcount--; + module_put(ldo->owner); spin_unlock_irqrestore(&tty_ldisc_lock, flags); + kfree(ld); } -static void * tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) +static void *tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos) { return (*pos < NR_LDISCS) ? pos : NULL; } -static void * tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) +static void *tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos) { (*pos)++; return (*pos < NR_LDISCS) ? pos : NULL; @@ -219,12 +226,13 @@ static void tty_ldiscs_seq_stop(struct seq_file *m, void *v) static int tty_ldiscs_seq_show(struct seq_file *m, void *v) { int i = *(loff_t *)v; - struct tty_ldisc ld; - - if (tty_ldisc_get(i, &ld) < 0) + struct tty_ldisc *ld; + + ld = tty_ldisc_try_get(i); + if (IS_ERR(ld)) return 0; - seq_printf(m, "%-10s %2d\n", ld.ops->name ? ld.ops->name : "???", i); - tty_ldisc_put(ld.ops); + seq_printf(m, "%-10s %2d\n", ld->ops->name ? ld->ops->name : "???", i); + tty_ldisc_put(ld); return 0; } @@ -263,8 +271,7 @@ const struct file_operations tty_ldiscs_proc_fops = { static void tty_ldisc_assign(struct tty_struct *tty, struct tty_ldisc *ld) { - ld->refcount = 0; - tty->ldisc = *ld; + tty->ldisc = ld; } /** @@ -286,7 +293,7 @@ static int tty_ldisc_try(struct tty_struct *tty) int ret = 0; spin_lock_irqsave(&tty_ldisc_lock, flags); - ld = &tty->ldisc; + ld = tty->ldisc; if (test_bit(TTY_LDISC, &tty->flags)) { ld->refcount++; ret = 1; @@ -315,10 +322,9 @@ struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *tty) { /* wait_event is a macro */ wait_event(tty_ldisc_wait, tty_ldisc_try(tty)); - WARN_ON(tty->ldisc.refcount == 0); - return &tty->ldisc; + WARN_ON(tty->ldisc->refcount == 0); + return tty->ldisc; } - EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); /** @@ -335,10 +341,9 @@ EXPORT_SYMBOL_GPL(tty_ldisc_ref_wait); struct tty_ldisc *tty_ldisc_ref(struct tty_struct *tty) { if (tty_ldisc_try(tty)) - return &tty->ldisc; + return tty->ldisc; return NULL; } - EXPORT_SYMBOL_GPL(tty_ldisc_ref); /** @@ -366,7 +371,6 @@ void tty_ldisc_deref(struct tty_ldisc *ld) wake_up(&tty_ldisc_wait); spin_unlock_irqrestore(&tty_ldisc_lock, flags); } - EXPORT_SYMBOL_GPL(tty_ldisc_deref); /** @@ -389,6 +393,26 @@ void tty_ldisc_enable(struct tty_struct *tty) } /** + * tty_ldisc_flush - flush line discipline queue + * @tty: tty + * + * Flush the line discipline queue (if any) for this tty. If there + * is no line discipline active this is a no-op. + */ + +void tty_ldisc_flush(struct tty_struct *tty) +{ + struct tty_ldisc *ld = tty_ldisc_ref(tty); + if (ld) { + if (ld->ops->flush_buffer) + ld->ops->flush_buffer(tty); + tty_ldisc_deref(ld); + } + tty_buffer_flush(tty); +} +EXPORT_SYMBOL_GPL(tty_ldisc_flush); + +/** * tty_set_termios_ldisc - set ldisc field * @tty: tty structure * @num: line discipline number @@ -407,6 +431,39 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) mutex_unlock(&tty->termios_mutex); } +/** + * tty_ldisc_open - open a line discipline + * @tty: tty we are opening the ldisc on + * @ld: discipline to open + * + * A helper opening method. Also a convenient debugging and check + * point. + */ + +static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) +{ + WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags)); + if (ld->ops->open) + return ld->ops->open(tty); + return 0; +} + +/** + * tty_ldisc_close - close a line discipline + * @tty: tty we are opening the ldisc on + * @ld: discipline to close + * + * A helper close method. Also a convenient debugging and check + * point. + */ + +static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) +{ + WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); + clear_bit(TTY_LDISC_OPEN, &tty->flags); + if (ld->ops->close) + ld->ops->close(tty); +} /** * tty_ldisc_restore - helper for tty ldisc change @@ -420,66 +477,136 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num) static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old) { char buf[64]; - struct tty_ldisc new_ldisc; + struct tty_ldisc *new_ldisc; + int r; /* There is an outstanding reference here so this is safe */ - tty_ldisc_get(old->ops->num, old); + old = tty_ldisc_get(old->ops->num); + WARN_ON(IS_ERR(old)); tty_ldisc_assign(tty, old); tty_set_termios_ldisc(tty, old->ops->num); - if (old->ops->open && (old->ops->open(tty) < 0)) { - tty_ldisc_put(old->ops); + if (tty_ldisc_open(tty, old) < 0) { + tty_ldisc_put(old); /* This driver is always present */ - if (tty_ldisc_get(N_TTY, &new_ldisc) < 0) + new_ldisc = tty_ldisc_get(N_TTY); + if (IS_ERR(new_ldisc)) panic("n_tty: get"); - tty_ldisc_assign(tty, &new_ldisc); + tty_ldisc_assign(tty, new_ldisc); tty_set_termios_ldisc(tty, N_TTY); - if (new_ldisc.ops->open) { - int r = new_ldisc.ops->open(tty); - if (r < 0) - panic("Couldn't open N_TTY ldisc for " - "%s --- error %d.", - tty_name(tty, buf), r); - } + r = tty_ldisc_open(tty, new_ldisc); + if (r < 0) + panic("Couldn't open N_TTY ldisc for " + "%s --- error %d.", + tty_name(tty, buf), r); } } /** + * tty_ldisc_halt - shut down the line discipline + * @tty: tty device + * + * Shut down the line discipline and work queue for this tty device. + * The TTY_LDISC flag being cleared ensures no further references can + * be obtained while the delayed work queue halt ensures that no more + * data is fed to the ldisc. + * + * In order to wait for any existing references to complete see + * tty_ldisc_wait_idle. + */ + +static int tty_ldisc_halt(struct tty_struct *tty) +{ + clear_bit(TTY_LDISC, &tty->flags); + return cancel_delayed_work(&tty->buf.work); +} + +/** + * tty_ldisc_wait_idle - wait for the ldisc to become idle + * @tty: tty to wait for + * + * Wait for the line discipline to become idle. The discipline must + * have been halted for this to guarantee it remains idle. + * + * tty_ldisc_lock protects the ref counts currently. + */ + +static int tty_ldisc_wait_idle(struct tty_struct *tty) +{ + unsigned long flags; + spin_lock_irqsave(&tty_ldisc_lock, flags); + while (tty->ldisc->refcount) { + spin_unlock_irqrestore(&tty_ldisc_lock, flags); + if (wait_event_timeout(tty_ldisc_wait, + tty->ldisc->refcount == 0, 5 * HZ) == 0) + return -EBUSY; + spin_lock_irqsave(&tty_ldisc_lock, flags); + } + spin_unlock_irqrestore(&tty_ldisc_lock, flags); + return 0; +} + +/** * tty_set_ldisc - set line discipline * @tty: the terminal to set * @ldisc: the line discipline * * Set the discipline of a tty line. Must be called from a process - * context. + * context. The ldisc change logic has to protect itself against any + * overlapping ldisc change (including on the other end of pty pairs), + * the close of one side of a tty/pty pair, and eventually hangup. * - * Locking: takes tty_ldisc_lock. - * called functions take termios_mutex + * Locking: takes tty_ldisc_lock, termios_mutex */ int tty_set_ldisc(struct tty_struct *tty, int ldisc) { int retval; - struct tty_ldisc o_ldisc, new_ldisc; - int work; - unsigned long flags; + struct tty_ldisc *o_ldisc, *new_ldisc; + int work, o_work = 0; struct tty_struct *o_tty; -restart: - /* This is a bit ugly for now but means we can break the 'ldisc - is part of the tty struct' assumption later */ - retval = tty_ldisc_get(ldisc, &new_ldisc); - if (retval) - return retval; + new_ldisc = tty_ldisc_get(ldisc); + if (IS_ERR(new_ldisc)) + return PTR_ERR(new_ldisc); + + /* + * We need to look at the tty locking here for pty/tty pairs + * when both sides try to change in parallel. + */ + + o_tty = tty->link; /* o_tty is the pty side or NULL */ + + + /* + * Check the no-op case + */ + + if (tty->ldisc->ops->num == ldisc) { + tty_ldisc_put(new_ldisc); + return 0; + } /* * Problem: What do we do if this blocks ? + * We could deadlock here */ tty_wait_until_sent(tty, 0); - if (tty->ldisc.ops->num == ldisc) { - tty_ldisc_put(new_ldisc.ops); - return 0; + mutex_lock(&tty->ldisc_mutex); + + /* + * We could be midstream of another ldisc change which has + * dropped the lock during processing. If so we need to wait. + */ + + while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { + mutex_unlock(&tty->ldisc_mutex); + wait_event(tty_ldisc_wait, + test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); + mutex_lock(&tty->ldisc_mutex); } + set_bit(TTY_LDISC_CHANGING, &tty->flags); /* * No more input please, we are switching. The new ldisc @@ -489,8 +616,6 @@ restart: tty->receive_room = 0; o_ldisc = tty->ldisc; - o_tty = tty->link; - /* * Make sure we don't change while someone holds a * reference to the line discipline. The TTY_LDISC bit @@ -501,108 +626,181 @@ restart: * with a userspace app continually trying to use the tty in * parallel to the change and re-referencing the tty. */ - clear_bit(TTY_LDISC, &tty->flags); - if (o_tty) - clear_bit(TTY_LDISC, &o_tty->flags); - spin_lock_irqsave(&tty_ldisc_lock, flags); - if (tty->ldisc.refcount || (o_tty && o_tty->ldisc.refcount)) { - if (tty->ldisc.refcount) { - /* Free the new ldisc we grabbed. Must drop the lock - first. */ - spin_unlock_irqrestore(&tty_ldisc_lock, flags); - tty_ldisc_put(o_ldisc.ops); - /* - * There are several reasons we may be busy, including - * random momentary I/O traffic. We must therefore - * retry. We could distinguish between blocking ops - * and retries if we made tty_ldisc_wait() smarter. - * That is up for discussion. - */ - if (wait_event_interruptible(tty_ldisc_wait, tty->ldisc.refcount == 0) < 0) - return -ERESTARTSYS; - goto restart; - } - if (o_tty && o_tty->ldisc.refcount) { - spin_unlock_irqrestore(&tty_ldisc_lock, flags); - tty_ldisc_put(o_tty->ldisc.ops); - if (wait_event_interruptible(tty_ldisc_wait, o_tty->ldisc.refcount == 0) < 0) - return -ERESTARTSYS; - goto restart; - } - } - /* - * If the TTY_LDISC bit is set, then we are racing against - * another ldisc change - */ - if (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { - struct tty_ldisc *ld; - spin_unlock_irqrestore(&tty_ldisc_lock, flags); - tty_ldisc_put(new_ldisc.ops); - ld = tty_ldisc_ref_wait(tty); - tty_ldisc_deref(ld); - goto restart; - } - /* - * This flag is used to avoid two parallel ldisc changes. Once - * open and close are fine grained locked this may work better - * as a mutex shared with the open/close/hup paths - */ - set_bit(TTY_LDISC_CHANGING, &tty->flags); + work = tty_ldisc_halt(tty); if (o_tty) - set_bit(TTY_LDISC_CHANGING, &o_tty->flags); - spin_unlock_irqrestore(&tty_ldisc_lock, flags); - - /* - * From this point on we know nobody has an ldisc - * usage reference, nor can they obtain one until - * we say so later on. - */ + o_work = tty_ldisc_halt(o_tty); - work = cancel_delayed_work(&tty->buf.work); /* - * Wait for ->hangup_work and ->buf.work handlers to terminate - * MUST NOT hold locks here. + * Wait for ->hangup_work and ->buf.work handlers to terminate. + * We must drop the mutex here in case a hangup is also in process. */ + + mutex_unlock(&tty->ldisc_mutex); + flush_scheduled_work(); + + /* Let any existing reference holders finish */ + retval = tty_ldisc_wait_idle(tty); + if (retval < 0) { + clear_bit(TTY_LDISC_CHANGING, &tty->flags); + tty_ldisc_put(new_ldisc); + return retval; + } + + mutex_lock(&tty->ldisc_mutex); + if (test_bit(TTY_HUPPED, &tty->flags)) { + /* We were raced by the hangup method. It will have stomped + the ldisc data and closed the ldisc down */ + clear_bit(TTY_LDISC_CHANGING, &tty->flags); + mutex_unlock(&tty->ldisc_mutex); + tty_ldisc_put(new_ldisc); + return -EIO; + } + /* Shutdown the current discipline. */ - if (o_ldisc.ops->close) - (o_ldisc.ops->close)(tty); + tty_ldisc_close(tty, o_ldisc); /* Now set up the new line discipline. */ - tty_ldisc_assign(tty, &new_ldisc); + tty_ldisc_assign(tty, new_ldisc); tty_set_termios_ldisc(tty, ldisc); - if (new_ldisc.ops->open) - retval = (new_ldisc.ops->open)(tty); + + retval = tty_ldisc_open(tty, new_ldisc); if (retval < 0) { - tty_ldisc_put(new_ldisc.ops); - tty_ldisc_restore(tty, &o_ldisc); + /* Back to the old one or N_TTY if we can't */ + tty_ldisc_put(new_ldisc); + tty_ldisc_restore(tty, o_ldisc); } + /* At this point we hold a reference to the new ldisc and a a reference to the old ldisc. If we ended up flipping back to the existing ldisc we have two references to it */ - if (tty->ldisc.ops->num != o_ldisc.ops->num && tty->ops->set_ldisc) + if (tty->ldisc->ops->num != o_ldisc->ops->num && tty->ops->set_ldisc) tty->ops->set_ldisc(tty); - tty_ldisc_put(o_ldisc.ops); + tty_ldisc_put(o_ldisc); /* - * Allow ldisc referencing to occur as soon as the driver - * ldisc callback completes. + * Allow ldisc referencing to occur again */ tty_ldisc_enable(tty); if (o_tty) tty_ldisc_enable(o_tty); - /* Restart it in case no characters kick it off. Safe if + /* Restart the work queue in case no characters kick it off. Safe if already running */ if (work) schedule_delayed_work(&tty->buf.work, 1); + if (o_work) + schedule_delayed_work(&o_tty->buf.work, 1); + mutex_unlock(&tty->ldisc_mutex); return retval; } +/** + * tty_reset_termios - reset terminal state + * @tty: tty to reset + * + * Restore a terminal to the driver default state. + */ + +static void tty_reset_termios(struct tty_struct *tty) +{ + mutex_lock(&tty->termios_mutex); + *tty->termios = tty->driver->init_termios; + tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios); + tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios); + mutex_unlock(&tty->termios_mutex); +} + + +/** + * tty_ldisc_reinit - reinitialise the tty ldisc + * @tty: tty to reinit + * + * Switch the tty back to N_TTY line discipline and leave the + * ldisc state closed + */ + +static void tty_ldisc_reinit(struct tty_struct *tty) +{ + struct tty_ldisc *ld; + + tty_ldisc_close(tty, tty->ldisc); + tty_ldisc_put(tty->ldisc); + tty->ldisc = NULL; + /* + * Switch the line discipline back + */ + ld = tty_ldisc_get(N_TTY); + BUG_ON(IS_ERR(ld)); + tty_ldisc_assign(tty, ld); + tty_set_termios_ldisc(tty, N_TTY); +} + +/** + * tty_ldisc_hangup - hangup ldisc reset + * @tty: tty being hung up + * + * Some tty devices reset their termios when they receive a hangup + * event. In that situation we must also switch back to N_TTY properly + * before we reset the termios data. + * + * Locking: We can take the ldisc mutex as the rest of the code is + * careful to allow for this. + * + * In the pty pair case this occurs in the close() path of the + * tty itself so we must be careful about locking rules. + */ + +void tty_ldisc_hangup(struct tty_struct *tty) +{ + struct tty_ldisc *ld; + + /* + * FIXME! What are the locking issues here? This may me overdoing + * things... This question is especially important now that we've + * removed the irqlock. + */ + ld = tty_ldisc_ref(tty); + if (ld != NULL) { + /* We may have no line discipline at this point */ + if (ld->ops->flush_buffer) + ld->ops->flush_buffer(tty); + tty_driver_flush_buffer(tty); + if ((test_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) && + ld->ops->write_wakeup) + ld->ops->write_wakeup(tty); + if (ld->ops->hangup) + ld->ops->hangup(tty); + tty_ldisc_deref(ld); + } + /* + * FIXME: Once we trust the LDISC code better we can wait here for + * ldisc completion and fix the driver call race + */ + wake_up_interruptible_poll(&tty->write_wait, POLLOUT); + wake_up_interruptible_poll(&tty->read_wait, POLLIN); + /* + * Shutdown the current line discipline, and reset it to + * N_TTY. + */ + if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) { + /* Avoid racing set_ldisc */ + mutex_lock(&tty->ldisc_mutex); + /* Switch back to N_TTY */ + tty_ldisc_reinit(tty); + /* At this point we have a closed ldisc and we want to + reopen it. We could defer this to the next open but + it means auditing a lot of other paths so this is a FIXME */ + WARN_ON(tty_ldisc_open(tty, tty->ldisc)); + tty_ldisc_enable(tty); + mutex_unlock(&tty->ldisc_mutex); + tty_reset_termios(tty); + } +} /** * tty_ldisc_setup - open line discipline @@ -610,24 +808,23 @@ restart: * @o_tty: pair tty for pty/tty pairs * * Called during the initial open of a tty/pty pair in order to set up the - * line discplines and bind them to the tty. + * line disciplines and bind them to the tty. This has no locking issues + * as the device isn't yet active. */ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) { - struct tty_ldisc *ld = &tty->ldisc; + struct tty_ldisc *ld = tty->ldisc; int retval; - if (ld->ops->open) { - retval = (ld->ops->open)(tty); - if (retval) - return retval; - } - if (o_tty && o_tty->ldisc.ops->open) { - retval = (o_tty->ldisc.ops->open)(o_tty); + retval = tty_ldisc_open(tty, ld); + if (retval) + return retval; + + if (o_tty) { + retval = tty_ldisc_open(o_tty, o_tty->ldisc); if (retval) { - if (ld->ops->close) - (ld->ops->close)(tty); + tty_ldisc_close(tty, ld); return retval; } tty_ldisc_enable(o_tty); @@ -635,32 +832,25 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) tty_ldisc_enable(tty); return 0; } - /** * tty_ldisc_release - release line discipline * @tty: tty being shut down * @o_tty: pair tty for pty/tty pairs * - * Called during the final close of a tty/pty pair in order to shut down the - * line discpline layer. + * Called during the final close of a tty/pty pair in order to shut down + * the line discpline layer. On exit the ldisc assigned is N_TTY and the + * ldisc has not been opened. */ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) { - unsigned long flags; - struct tty_ldisc ld; /* * Prevent flush_to_ldisc() from rescheduling the work for later. Then * kill any delayed work. As this is the final close it does not * race with the set_ldisc code path. */ - clear_bit(TTY_LDISC, &tty->flags); - cancel_delayed_work(&tty->buf.work); - - /* - * Wait for ->hangup_work and ->buf.work handlers to terminate - */ + tty_ldisc_halt(tty); flush_scheduled_work(); /* @@ -668,38 +858,19 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) * side waiters as the file is closing so user count on the file * side is zero. */ - spin_lock_irqsave(&tty_ldisc_lock, flags); - while (tty->ldisc.refcount) { - spin_unlock_irqrestore(&tty_ldisc_lock, flags); - wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0); - spin_lock_irqsave(&tty_ldisc_lock, flags); - } - spin_unlock_irqrestore(&tty_ldisc_lock, flags); + + tty_ldisc_wait_idle(tty); + /* * Shutdown the current line discipline, and reset it to N_TTY. * * FIXME: this MUST get fixed for the new reflocking */ - if (tty->ldisc.ops->close) - (tty->ldisc.ops->close)(tty); - tty_ldisc_put(tty->ldisc.ops); - /* - * Switch the line discipline back - */ - WARN_ON(tty_ldisc_get(N_TTY, &ld)); - tty_ldisc_assign(tty, &ld); - tty_set_termios_ldisc(tty, N_TTY); - if (o_tty) { - /* FIXME: could o_tty be in setldisc here ? */ - clear_bit(TTY_LDISC, &o_tty->flags); - if (o_tty->ldisc.ops->close) - (o_tty->ldisc.ops->close)(o_tty); - tty_ldisc_put(o_tty->ldisc.ops); - WARN_ON(tty_ldisc_get(N_TTY, &ld)); - tty_ldisc_assign(o_tty, &ld); - tty_set_termios_ldisc(o_tty, N_TTY); - } + tty_ldisc_reinit(tty); + /* This will need doing differently if we need to lock */ + if (o_tty) + tty_ldisc_release(o_tty, NULL); } /** @@ -712,10 +883,10 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) void tty_ldisc_init(struct tty_struct *tty) { - struct tty_ldisc ld; - if (tty_ldisc_get(N_TTY, &ld) < 0) + struct tty_ldisc *ld = tty_ldisc_get(N_TTY); + if (IS_ERR(ld)) panic("n_tty: init_tty"); - tty_ldisc_assign(tty, &ld); + tty_ldisc_assign(tty, ld); } void tty_ldisc_begin(void) |