diff options
| author | Alan Cox <alan@lxorguk.ukuu.org.uk> | 2008-04-30 11:53:29 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 19:29:40 +0400 |
| commit | 04f378b198da233ca0aca341b113dc6579d46123 (patch) | |
| tree | 696e7bd401125cee71ecaa2047c4273f38732554 /drivers/char/n_hdlc.c | |
| parent | e52384426064bca0669a954736206adca7595d48 (diff) | |
| download | linux-04f378b198da233ca0aca341b113dc6579d46123.tar.xz | |
tty: BKL pushdown
- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock
BKL now primarily protects open/close/ldisc change in the tty layer
[jirislaby@gmail.com: a couple of fixes]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/n_hdlc.c')
| -rw-r--r-- | drivers/char/n_hdlc.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c index 06803ed5568c..a07c0af4819e 100644 --- a/drivers/char/n_hdlc.c +++ b/drivers/char/n_hdlc.c @@ -578,26 +578,36 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, return -EFAULT; } + lock_kernel(); + for (;;) { - if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) + if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { + unlock_kernel(); return -EIO; + } n_hdlc = tty2n_hdlc (tty); if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || - tty != n_hdlc->tty) + tty != n_hdlc->tty) { + unlock_kernel(); return 0; + } rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); if (rbuf) break; /* no data */ - if (file->f_flags & O_NONBLOCK) + if (file->f_flags & O_NONBLOCK) { + unlock_kernel(); return -EAGAIN; + } interruptible_sleep_on (&tty->read_wait); - if (signal_pending(current)) + if (signal_pending(current)) { + unlock_kernel(); return -EINTR; + } } if (rbuf->count > nr) @@ -618,7 +628,7 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, kfree(rbuf); else n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf); - + unlock_kernel(); return ret; } /* end of n_hdlc_tty_read() */ @@ -661,6 +671,8 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, count = maxframe; } + lock_kernel(); + add_wait_queue(&tty->write_wait, &wait); set_current_state(TASK_INTERRUPTIBLE); @@ -695,7 +707,7 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); n_hdlc_send_frames(n_hdlc,tty); } - + unlock_kernel(); return error; } /* end of n_hdlc_tty_write() */ |