From ee2ffa0dfdd2db19705f2ba1c6a4c0bfe8122dd8 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:35 +1000 Subject: fs: cleanup files_lock locking fs: cleanup files_lock locking Lock tty_files with a new spinlock, tty_files_lock; provide helpers to manipulate the per-sb files list; unexport the files_lock spinlock. Cc: linux-kernel@vger.kernel.org Cc: Christoph Hellwig Cc: Alan Cox Acked-by: Andi Kleen Acked-by: Greg Kroah-Hartman Signed-off-by: Nick Piggin Signed-off-by: Al Viro --- drivers/char/pty.c | 6 +++++- drivers/char/tty_io.c | 26 ++++++++++++++++++-------- 2 files changed, 23 insertions(+), 9 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/pty.c b/drivers/char/pty.c index ad46eae..2c64faa 100644 --- a/drivers/char/pty.c +++ b/drivers/char/pty.c @@ -676,7 +676,11 @@ static int ptmx_open(struct inode *inode, struct file *filp) set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ filp->private_data = tty; - file_move(filp, &tty->tty_files); + + file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ + spin_lock(&tty_files_lock); + list_add(&filp->f_u.fu_list, &tty->tty_files); + spin_unlock(&tty_files_lock); retval = devpts_pty_new(inode, tty->link); if (retval) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 0350c42..cd5b829 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -136,6 +136,9 @@ LIST_HEAD(tty_drivers); /* linked list of tty drivers */ DEFINE_MUTEX(tty_mutex); EXPORT_SYMBOL(tty_mutex); +/* Spinlock to protect the tty->tty_files list */ +DEFINE_SPINLOCK(tty_files_lock); + static ssize_t tty_read(struct file *, char __user *, size_t, loff_t *); static ssize_t tty_write(struct file *, const char __user *, size_t, loff_t *); ssize_t redirected_tty_write(struct file *, const char __user *, @@ -235,11 +238,11 @@ static int check_tty_count(struct tty_struct *tty, const char *routine) struct list_head *p; int count = 0; - file_list_lock(); + spin_lock(&tty_files_lock); list_for_each(p, &tty->tty_files) { count++; } - file_list_unlock(); + spin_unlock(&tty_files_lock); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_SLAVE && tty->link && tty->link->count) @@ -519,7 +522,7 @@ void __tty_hangup(struct tty_struct *tty) workqueue with the lock held */ check_tty_count(tty, "tty_hangup"); - file_list_lock(); + spin_lock(&tty_files_lock); /* This breaks for file handles being sent over AF_UNIX sockets ? */ list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) { if (filp->f_op->write == redirected_tty_write) @@ -530,7 +533,7 @@ void __tty_hangup(struct tty_struct *tty) __tty_fasync(-1, filp, 0); /* can't block */ filp->f_op = &hung_up_tty_fops; } - file_list_unlock(); + spin_unlock(&tty_files_lock); tty_ldisc_hangup(tty); @@ -1424,9 +1427,9 @@ static void release_one_tty(struct work_struct *work) tty_driver_kref_put(driver); module_put(driver->owner); - file_list_lock(); + spin_lock(&tty_files_lock); list_del_init(&tty->tty_files); - file_list_unlock(); + spin_unlock(&tty_files_lock); put_pid(tty->pgrp); put_pid(tty->session); @@ -1671,7 +1674,10 @@ int tty_release(struct inode *inode, struct file *filp) * - do_tty_hangup no longer sees this file descriptor as * something that needs to be handled for hangups. */ - file_kill(filp); + spin_lock(&tty_files_lock); + BUG_ON(list_empty(&filp->f_u.fu_list)); + list_del_init(&filp->f_u.fu_list); + spin_unlock(&tty_files_lock); filp->private_data = NULL; /* @@ -1840,7 +1846,11 @@ got_driver: } filp->private_data = tty; - file_move(filp, &tty->tty_files); + BUG_ON(list_empty(&filp->f_u.fu_list)); + file_sb_list_del(filp); /* __dentry_open has put it on the sb list */ + spin_lock(&tty_files_lock); + list_add(&filp->f_u.fu_list, &tty->tty_files); + spin_unlock(&tty_files_lock); check_tty_count(tty, "tty_open"); if (tty->driver->type == TTY_DRIVER_TYPE_PTY && tty->driver->subtype == PTY_TYPE_MASTER) -- cgit v1.1