Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757520AbZKROmJ (ORCPT ); Wed, 18 Nov 2009 09:42:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757389AbZKROmH (ORCPT ); Wed, 18 Nov 2009 09:42:07 -0500 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:36884 "EHLO bob.linux.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757509AbZKROmG (ORCPT ); Wed, 18 Nov 2009 09:42:06 -0500 From: Alan Cox Subject: [RFC PATCH 1/5] tty: push the BKL down into the handlers a bit To: linux-kernel@vger.kernel.org Date: Wed, 18 Nov 2009 14:25:43 +0000 Message-ID: <20091118142404.3806.19238.stgit@localhost.localdomain> In-Reply-To: <20091118142313.3806.47368.stgit@localhost.localdomain> References: <20091118142313.3806.47368.stgit@localhost.localdomain> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 13801 Lines: 506 Start trying to untangle the remaining BKL mess Signed-off-by: Alan "I must be out of my tree" Cox --- drivers/char/pty.c | 2 - drivers/char/tty_io.c | 140 ++++++++++++++++++++++++++-------------------- drivers/char/tty_ldisc.c | 13 ++++ include/linux/tty.h | 2 - 4 files changed, 94 insertions(+), 63 deletions(-) diff --git a/drivers/char/pty.c b/drivers/char/pty.c index d516e9c..169cdcc 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -659,7 +659,7 @@ static int __ptmx_open(struct inode *inode, struct file *filp) if (!retval) return 0; out1: - tty_release_dev(filp); + tty_release(inode, filp); return retval; out: devpts_kill_index(inode, index); diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 59499ee..05e94a2 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -142,7 +142,6 @@ ssize_t redirected_tty_write(struct file *, const char __user *, size_t, loff_t *); static unsigned int tty_poll(struct file *, poll_table *); static int tty_open(struct inode *, struct file *); -static int tty_release(struct inode *, struct file *); long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg); #ifdef CONFIG_COMPAT static long tty_compat_ioctl(struct file *file, unsigned int cmd, @@ -1017,14 +1016,16 @@ out: void tty_write_message(struct tty_struct *tty, char *msg) { - lock_kernel(); if (tty) { mutex_lock(&tty->atomic_write_lock); - if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) + lock_kernel(); + if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) { + unlock_kernel(); tty->ops->write(tty, msg, strlen(msg)); + } else + unlock_kernel(); tty_write_unlock(tty); } - unlock_kernel(); return; } @@ -1202,14 +1203,21 @@ static int tty_driver_install_tty(struct tty_driver *driver, struct tty_struct *tty) { int idx = tty->index; + int ret; - if (driver->ops->install) - return driver->ops->install(driver, tty); + if (driver->ops->install) { + lock_kernel(); + ret = driver->ops->install(driver, tty); + unlock_kernel(); + return ret; + } if (tty_init_termios(tty) == 0) { + lock_kernel(); tty_driver_kref_get(driver); tty->count++; driver->ttys[idx] = tty; + unlock_kernel(); return 0; } return -ENOMEM; @@ -1302,10 +1310,14 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, struct tty_struct *tty; int retval; + lock_kernel(); /* Check if pty master is being opened multiple times */ if (driver->subtype == PTY_TYPE_MASTER && - (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) + (driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) { + unlock_kernel(); return ERR_PTR(-EIO); + } + unlock_kernel(); /* * First time open is complex, especially for PTY devices. @@ -1335,8 +1347,9 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, * If we fail here just call release_tty to clean up. No need * to decrement the use counts, as release_tty doesn't care. */ - + lock_kernel(); retval = tty_ldisc_setup(tty, tty->link); + unlock_kernel(); if (retval) goto release_mem_out; return tty; @@ -1350,7 +1363,9 @@ release_mem_out: if (printk_ratelimit()) printk(KERN_INFO "tty_init_dev: ldisc open failed, " "clearing slot %d\n", idx); + lock_kernel(); release_tty(tty, idx); + unlock_kernel(); return ERR_PTR(retval); } @@ -1464,7 +1479,17 @@ static void release_tty(struct tty_struct *tty, int idx) tty_kref_put(tty); } -/* +/** + * tty_release - vfs callback for close + * @inode: inode of tty + * @filp: file pointer for handle to tty + * + * Called the last time each file handle is closed that references + * this tty. There may however be several such references. + * + * Locking: + * Takes bkl. See tty_release_dev + * * Even releasing the tty structures is a tricky business.. We have * to be very careful that the structures are all released at the * same time, as interrupts might otherwise get the wrong pointers. @@ -1472,20 +1497,20 @@ static void release_tty(struct tty_struct *tty, int idx) * WSH 09/09/97: rewritten to avoid some nasty race conditions that could * lead to double frees or releasing memory still in use. */ -void tty_release_dev(struct file *filp) + +int tty_release(struct inode *inode, struct file *filp) { struct tty_struct *tty, *o_tty; int pty_master, tty_closing, o_tty_closing, do_sleep; int devpts; int idx; char buf[64]; - struct inode *inode; - inode = filp->f_path.dentry->d_inode; tty = (struct tty_struct *)filp->private_data; if (tty_paranoia_check(tty, inode, "tty_release_dev")) - return; + return 0; + lock_kernel(); check_tty_count(tty, "tty_release_dev"); tty_fasync(-1, filp, 0); @@ -1500,19 +1525,22 @@ void tty_release_dev(struct file *filp) if (idx < 0 || idx >= tty->driver->num) { printk(KERN_DEBUG "tty_release_dev: bad idx when trying to " "free (%s)\n", tty->name); - return; + unlock_kernel(); + return 0; } if (!devpts) { if (tty != tty->driver->ttys[idx]) { + unlock_kernel(); printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty " "for (%s)\n", idx, tty->name); - return; + return 0; } if (tty->termios != tty->driver->termios[idx]) { + unlock_kernel(); printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios " "for (%s)\n", idx, tty->name); - return; + return 0; } } #endif @@ -1526,26 +1554,29 @@ void tty_release_dev(struct file *filp) if (tty->driver->other && !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) { if (o_tty != tty->driver->other->ttys[idx]) { + unlock_kernel(); printk(KERN_DEBUG "tty_release_dev: other->table[%d] " "not o_tty for (%s)\n", idx, tty->name); - return; + return 0 ; } if (o_tty->termios != tty->driver->other->termios[idx]) { + unlock_kernel(); printk(KERN_DEBUG "tty_release_dev: other->termios[%d] " "not o_termios for (%s)\n", idx, tty->name); - return; + return 0; } if (o_tty->link != tty) { printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n"); - return; + return 0; } } #endif if (tty->ops->close) tty->ops->close(tty, filp); + unlock_kernel(); /* * Sanity check: if tty->count is going to zero, there shouldn't be * any waiters on tty->read_wait or tty->write_wait. We test the @@ -1568,6 +1599,7 @@ void tty_release_dev(struct file *filp) opens on /dev/tty */ mutex_lock(&tty_mutex); + lock_kernel(); tty_closing = tty->count <= 1; o_tty_closing = o_tty && (o_tty->count <= (pty_master ? 1 : 0)); @@ -1598,6 +1630,7 @@ void tty_release_dev(struct file *filp) printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue " "active!\n", tty_name(tty, buf)); + unlock_kernel(); mutex_unlock(&tty_mutex); schedule(); } @@ -1661,8 +1694,10 @@ void tty_release_dev(struct file *filp) mutex_unlock(&tty_mutex); /* check whether both sides are closing ... */ - if (!tty_closing || (o_tty && !o_tty_closing)) - return; + if (!tty_closing || (o_tty && !o_tty_closing)) { + unlock_kernel(); + return 0; + } #ifdef TTY_DEBUG_HANGUP printk(KERN_DEBUG "freeing tty structure..."); @@ -1680,10 +1715,12 @@ void tty_release_dev(struct file *filp) /* Make this pty number available for reallocation */ if (devpts) devpts_kill_index(inode, idx); + unlock_kernel(); + return 0; } /** - * __tty_open - open a tty device + * tty_open - open a tty device * @inode: inode of device file * @filp: file pointer to tty * @@ -1703,7 +1740,7 @@ void tty_release_dev(struct file *filp) * ->siglock protects ->signal/->sighand */ -static int __tty_open(struct inode *inode, struct file *filp) +static int tty_open(struct inode *inode, struct file *filp) { struct tty_struct *tty = NULL; int noctty, retval; @@ -1720,10 +1757,12 @@ retry_open: retval = 0; mutex_lock(&tty_mutex); + lock_kernel(); if (device == MKDEV(TTYAUX_MAJOR, 0)) { tty = get_current_tty(); if (!tty) { + unlock_kernel(); mutex_unlock(&tty_mutex); return -ENXIO; } @@ -1755,12 +1794,14 @@ retry_open: goto got_driver; } } + unlock_kernel(); mutex_unlock(&tty_mutex); return -ENODEV; } driver = get_tty_driver(device, &index); if (!driver) { + unlock_kernel(); mutex_unlock(&tty_mutex); return -ENODEV; } @@ -1770,6 +1811,7 @@ got_driver: tty = tty_driver_lookup_tty(driver, inode, index); if (IS_ERR(tty)) { + unlock_kernel(); mutex_unlock(&tty_mutex); return PTR_ERR(tty); } @@ -1784,8 +1826,10 @@ got_driver: mutex_unlock(&tty_mutex); tty_driver_kref_put(driver); - if (IS_ERR(tty)) + if (IS_ERR(tty)) { + unlock_kernel(); return PTR_ERR(tty); + } filp->private_data = tty; file_move(filp, &tty->tty_files); @@ -1813,11 +1857,15 @@ got_driver: printk(KERN_DEBUG "error %d in opening %s...", retval, tty->name); #endif - tty_release_dev(filp); - if (retval != -ERESTARTSYS) + tty_release(inode, filp); + if (retval != -ERESTARTSYS) { + unlock_kernel(); return retval; - if (signal_pending(current)) + } + if (signal_pending(current)) { + unlock_kernel(); return retval; + } schedule(); /* * Need to reset f_op in case a hangup happened. @@ -1826,8 +1874,11 @@ got_driver: filp->f_op = &tty_fops; goto retry_open; } + unlock_kernel(); + mutex_lock(&tty_mutex); + lock_kernel(); spin_lock_irq(¤t->sighand->siglock); if (!noctty && current->signal->leader && @@ -1835,44 +1886,13 @@ got_driver: tty->session == NULL) __proc_set_tty(current, tty); spin_unlock_irq(¤t->sighand->siglock); + unlock_kernel(); mutex_unlock(&tty_mutex); return 0; } -/* BKL pushdown: scary code avoidance wrapper */ -static int tty_open(struct inode *inode, struct file *filp) -{ - int ret; - - lock_kernel(); - ret = __tty_open(inode, filp); - unlock_kernel(); - return ret; -} - - -/** - * tty_release - vfs callback for close - * @inode: inode of tty - * @filp: file pointer for handle to tty - * - * Called the last time each file handle is closed that references - * this tty. There may however be several such references. - * - * Locking: - * Takes bkl. See tty_release_dev - */ - -static int tty_release(struct inode *inode, struct file *filp) -{ - lock_kernel(); - tty_release_dev(filp); - unlock_kernel(); - return 0; -} - /** * tty_poll - check tty status * @filp: file being polled @@ -2317,9 +2337,7 @@ static int tiocsetd(struct tty_struct *tty, int __user *p) if (get_user(ldisc, p)) return -EFAULT; - lock_kernel(); ret = tty_set_ldisc(tty, ldisc); - unlock_kernel(); return ret; } diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c index feb5507..d914e77 100644 --- a/drivers/char/tty_ldisc.c +++ b/drivers/char/tty_ldisc.c @@ -34,6 +34,8 @@ #include #include +#include /* For the moment */ + #include #include @@ -545,6 +547,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) if (IS_ERR(new_ldisc)) return PTR_ERR(new_ldisc); + lock_kernel(); /* * We need to look at the tty locking here for pty/tty pairs * when both sides try to change in parallel. @@ -558,6 +561,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) */ if (tty->ldisc->ops->num == ldisc) { + unlock_kernel(); tty_ldisc_put(new_ldisc); return 0; } @@ -569,6 +573,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) tty_wait_until_sent(tty, 0); + unlock_kernel(); mutex_lock(&tty->ldisc_mutex); /* @@ -582,6 +587,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); mutex_lock(&tty->ldisc_mutex); } + + lock_kernel(); + set_bit(TTY_LDISC_CHANGING, &tty->flags); /* @@ -592,6 +600,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) tty->receive_room = 0; o_ldisc = tty->ldisc; + + unlock_kernel(); /* * Make sure we don't change while someone holds a * reference to the line discipline. The TTY_LDISC bit @@ -617,12 +627,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) flush_scheduled_work(); mutex_lock(&tty->ldisc_mutex); + lock_kernel(); 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); + unlock_kernel(); return -EIO; } @@ -664,6 +676,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) if (o_work) schedule_delayed_work(&o_tty->buf.work, 1); mutex_unlock(&tty->ldisc_mutex); + unlock_kernel(); return retval; } diff --git a/include/linux/tty.h b/include/linux/tty.h index e6da667..405a903 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -449,7 +449,7 @@ extern void initialize_tty_struct(struct tty_struct *tty, struct tty_driver *driver, int idx); extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx, int first_ok); -extern void tty_release_dev(struct file *filp); +extern int tty_release(struct inode *inode, struct file *filp); extern int tty_init_termios(struct tty_struct *tty); extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/