From ee2ffa0dfdd2db19705f2ba1c6a4c0bfe8122dd8 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 18 Aug 2010 04:37:35 +1000 Subject: [PATCH] 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 +++++++++++++++++-------- fs/file_table.c | 42 +++++++++++++++++----------------------- fs/open.c | 4 ++-- include/linux/fs.h | 7 ++----- include/linux/tty.h | 1 + security/selinux/hooks.c | 4 ++-- 7 files changed, 48 insertions(+), 42 deletions(-) diff --git a/drivers/char/pty.c b/drivers/char/pty.c index ad46eae1f9bb..2c64faa8efa4 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 0350c42375a2..cd5b829634ea 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) diff --git a/fs/file_table.c b/fs/file_table.c index edecd36fed9b..6f0e62ecfddd 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -32,8 +32,7 @@ struct files_stat_struct files_stat = { .max_files = NR_FILE }; -/* public. Not pretty! */ -__cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(files_lock); /* SLAB cache for file structures */ static struct kmem_cache *filp_cachep __read_mostly; @@ -249,7 +248,7 @@ static void __fput(struct file *file) cdev_put(inode->i_cdev); fops_put(file->f_op); put_pid(file->f_owner.pid); - file_kill(file); + file_sb_list_del(file); if (file->f_mode & FMODE_WRITE) drop_file_write_access(file); file->f_path.dentry = NULL; @@ -328,31 +327,29 @@ struct file *fget_light(unsigned int fd, int *fput_needed) return file; } - void put_filp(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) { security_file_free(file); - file_kill(file); + file_sb_list_del(file); file_free(file); } } -void file_move(struct file *file, struct list_head *list) +void file_sb_list_add(struct file *file, struct super_block *sb) { - if (!list) - return; - file_list_lock(); - list_move(&file->f_u.fu_list, list); - file_list_unlock(); + spin_lock(&files_lock); + BUG_ON(!list_empty(&file->f_u.fu_list)); + list_add(&file->f_u.fu_list, &sb->s_files); + spin_unlock(&files_lock); } -void file_kill(struct file *file) +void file_sb_list_del(struct file *file) { if (!list_empty(&file->f_u.fu_list)) { - file_list_lock(); + spin_lock(&files_lock); list_del_init(&file->f_u.fu_list); - file_list_unlock(); + spin_unlock(&files_lock); } } @@ -361,7 +358,7 @@ int fs_may_remount_ro(struct super_block *sb) struct file *file; /* Check that no files are currently opened for writing. */ - file_list_lock(); + spin_lock(&files_lock); list_for_each_entry(file, &sb->s_files, f_u.fu_list) { struct inode *inode = file->f_path.dentry->d_inode; @@ -373,10 +370,10 @@ int fs_may_remount_ro(struct super_block *sb) if (S_ISREG(inode->i_mode) && (file->f_mode & FMODE_WRITE)) goto too_bad; } - file_list_unlock(); + spin_unlock(&files_lock); return 1; /* Tis' cool bro. */ too_bad: - file_list_unlock(); + spin_unlock(&files_lock); return 0; } @@ -392,7 +389,7 @@ void mark_files_ro(struct super_block *sb) struct file *f; retry: - file_list_lock(); + spin_lock(&files_lock); list_for_each_entry(f, &sb->s_files, f_u.fu_list) { struct vfsmount *mnt; if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) @@ -408,16 +405,13 @@ retry: continue; file_release_write(f); mnt = mntget(f->f_path.mnt); - file_list_unlock(); - /* - * This can sleep, so we can't hold - * the file_list_lock() spinlock. - */ + /* This can sleep, so we can't hold the spinlock. */ + spin_unlock(&files_lock); mnt_drop_write(mnt); mntput(mnt); goto retry; } - file_list_unlock(); + spin_unlock(&files_lock); } void __init files_init(unsigned long mempages) diff --git a/fs/open.c b/fs/open.c index 630715f9f73d..d74e1983e8dc 100644 --- a/fs/open.c +++ b/fs/open.c @@ -675,7 +675,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, f->f_path.mnt = mnt; f->f_pos = 0; f->f_op = fops_get(inode->i_fop); - file_move(f, &inode->i_sb->s_files); + file_sb_list_add(f, inode->i_sb); error = security_dentry_open(f, cred); if (error) @@ -721,7 +721,7 @@ cleanup_all: mnt_drop_write(mnt); } } - file_kill(f); + file_sb_list_del(f); f->f_path.dentry = NULL; f->f_path.mnt = NULL; cleanup_file: diff --git a/include/linux/fs.h b/include/linux/fs.h index 29f7c975304c..5a9a9e5a3705 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -944,9 +944,6 @@ struct file { unsigned long f_mnt_write_state; #endif }; -extern spinlock_t files_lock; -#define file_list_lock() spin_lock(&files_lock); -#define file_list_unlock() spin_unlock(&files_lock); #define get_file(x) atomic_long_inc(&(x)->f_count) #define fput_atomic(x) atomic_long_add_unless(&(x)->f_count, -1, 1) @@ -2188,8 +2185,8 @@ static inline void insert_inode_hash(struct inode *inode) { __insert_inode_hash(inode, inode->i_ino); } -extern void file_move(struct file *f, struct list_head *list); -extern void file_kill(struct file *f); +extern void file_sb_list_add(struct file *f, struct super_block *sb); +extern void file_sb_list_del(struct file *f); #ifdef CONFIG_BLOCK extern void submit_bio(int, struct bio *); extern int bdev_read_only(struct block_device *); diff --git a/include/linux/tty.h b/include/linux/tty.h index 1437da3ddc62..f6b371a2514e 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -470,6 +470,7 @@ extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty); extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty); extern struct mutex tty_mutex; +extern spinlock_t tty_files_lock; extern void tty_write_unlock(struct tty_struct *tty); extern int tty_write_lock(struct tty_struct *tty, int ndelay); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 42043f96e54f..bd7da0f0ccf3 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2170,7 +2170,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, tty = get_current_tty(); if (tty) { - file_list_lock(); + spin_lock(&tty_files_lock); if (!list_empty(&tty->tty_files)) { struct inode *inode; @@ -2186,7 +2186,7 @@ static inline void flush_unauthorized_files(const struct cred *cred, drop_tty = 1; } } - file_list_unlock(); + spin_unlock(&tty_files_lock); tty_kref_put(tty); } /* Reset controlling tty. */ -- 2.20.1