Commit 0895269a authored by Russell King's avatar Russell King Committed by Linus Torvalds

[PATCH] Alternative tty fasync fix

Instead of detecting when filp->private_data becomes NULL in
do_tty_hangup and check_tty_count, we remove the file descriptor
from the list of descriptors associated with the tty.  We use the
same method that dentry_open() uses.

(It also cleans that up to use a "file_kill()" instead of using a dummy
"kill_list()" that leaves pointers to stale stack entries that are never
used)

In addition, we change the for() loops into real list_for_each()
or list_for_each_entry loops as appropriate.
parent 260f6c51
......@@ -232,8 +232,7 @@ static int check_tty_count(struct tty_struct *tty, const char *routine)
int count = 0;
file_list_lock();
for(p = tty->tty_files.next; p != &tty->tty_files; p = p->next) {
if(list_entry(p, struct file, f_list)->private_data == tty)
list_for_each(p, &tty->tty_files) {
count++;
}
file_list_unlock();
......@@ -441,8 +440,8 @@ void do_tty_hangup(void *data)
{
struct tty_struct *tty = (struct tty_struct *) data;
struct file * cons_filp = NULL;
struct file *filp;
struct task_struct *p;
struct list_head *l;
struct pid *pid;
int closecount = 0, n;
......@@ -454,15 +453,7 @@ void do_tty_hangup(void *data)
check_tty_count(tty, "do_tty_hangup");
file_list_lock();
for (l = tty->tty_files.next; l != &tty->tty_files; l = l->next) {
struct file * filp = list_entry(l, struct file, f_list);
/*
* If this file descriptor has been closed, ignore it; it
* will be going away shortly. (We don't test filp->f_count
* for zero since that could open another race.) --rmk
*/
if (filp->private_data == NULL)
continue;
list_for_each_entry(filp, &tty->tty_files, f_list) {
if (IS_CONSOLE_DEV(filp->f_dentry->d_inode->i_rdev) ||
IS_SYSCONS_DEV(filp->f_dentry->d_inode->i_rdev)) {
cons_filp = filp;
......@@ -517,7 +508,8 @@ void do_tty_hangup(void *data)
}
read_lock(&tasklist_lock);
if (tty->session > 0)
if (tty->session > 0) {
struct list_head *l;
for_each_task_pid(tty->session, PIDTYPE_SID, p, l, pid) {
if (p->tty == tty)
p->tty = NULL;
......@@ -528,6 +520,7 @@ void do_tty_hangup(void *data)
if (tty->pgrp > 0)
p->tty_old_pgrp = tty->pgrp;
}
}
read_unlock(&tasklist_lock);
tty->flags = 0;
......@@ -1227,14 +1220,16 @@ static void release_dev(struct file * filp)
}
/*
* We've decremented tty->count, so we should zero out
* filp->private_data, to break the link between the tty and
* the file descriptor. Otherwise if filp_close() blocks before
* the file descriptor is removed from the inuse_filp
* list, check_tty_count() could observe a discrepancy and
* printk a warning message to the user.
* We've decremented tty->count, so we need to remove this file
* descriptor off the tty->tty_files list; this serves two
* purposes:
* - check_tty_count sees the correct number of file descriptors
* associated with this tty.
* - do_tty_hangup no longer sees this file descriptor as
* something that needs to be handled for hangups.
*/
filp->private_data = 0;
file_kill(filp);
filp->private_data = NULL;
/*
* Perform some housekeeping before deciding whether to return.
......
......@@ -188,6 +188,13 @@ void file_move(struct file *file, struct list_head *list)
file_list_unlock();
}
void file_kill(struct file *file)
{
file_list_lock();
list_del_init(&file->f_list);
file_list_unlock();
}
int fs_may_remount_ro(struct super_block *sb)
{
struct list_head *p;
......
......@@ -638,7 +638,6 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
{
struct file * f;
struct inode *inode;
static LIST_HEAD(kill_list);
int error;
error = -ENFILE;
......@@ -683,7 +682,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
fops_put(f->f_op);
if (f->f_mode & FMODE_WRITE)
put_write_access(inode);
file_move(f, &kill_list); /* out of the way.. */
file_kill(f);
f->f_dentry = NULL;
f->f_vfsmnt = NULL;
cleanup_file:
......
......@@ -1183,6 +1183,7 @@ static inline void insert_inode_hash(struct inode *inode) {
extern struct file * get_empty_filp(void);
extern void file_move(struct file *f, struct list_head *list);
extern void file_kill(struct file *f);
struct bio;
extern int submit_bio(int, struct bio *);
extern int bdev_read_only(struct block_device *);
......
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