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tty: use lock guard()s in tty_io 

guard()s and scoped_guard()s express more clearly what is protected by
locks. And also makes the code cleaner as it can return immediately in
case of short returns.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250425111315.1036184-3-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2025-04-25 13:13:11 +02:00 committed by Greg Kroah-Hartman
parent 3eabc1a34b
commit f49573f2f5
1 changed files with 40 additions and 56 deletions
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96
drivers/tty/tty_io.c
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@ -276,11 +276,10 @@ static void check_tty_count(struct tty_struct *tty, const char *routine)
struct list_head *p; struct list_head *p;
int count = 0, kopen_count = 0; int count = 0, kopen_count = 0;
spin_lock(&tty->files_lock); scoped_guard(spinlock, &tty->files_lock)
list_for_each(p, &tty->tty_files) { list_for_each(p, &tty->tty_files)
count++; count++;
}
spin_unlock(&tty->files_lock);
if (tty->driver->type == TTY_DRIVER_TYPE_PTY && if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_SLAVE && tty->driver->subtype == PTY_TYPE_SLAVE &&
tty->link && tty->link->count) tty->link && tty->link->count)
@ -378,7 +377,7 @@ EXPORT_SYMBOL_GPL(tty_dev_name_to_number);
*/ */
struct tty_driver *tty_find_polling_driver(char *name, int *line) struct tty_driver *tty_find_polling_driver(char *name, int *line)
{ {
struct tty_driver *p, *res = NULL; struct tty_driver *p;
int tty_line = 0; int tty_line = 0;
int len; int len;
char *str, *stp; char *str, *stp;
@ -392,7 +391,8 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
len = str - name; len = str - name;
tty_line = simple_strtoul(str, &str, 10); tty_line = simple_strtoul(str, &str, 10);
mutex_lock(&tty_mutex); guard(mutex)(&tty_mutex);
/* Search through the tty devices to look for a match */ /* Search through the tty devices to look for a match */
list_for_each_entry(p, &tty_drivers, tty_drivers) { list_for_each_entry(p, &tty_drivers, tty_drivers) {
if (!len || strncmp(name, p->name, len) != 0) if (!len || strncmp(name, p->name, len) != 0)
@ -405,14 +405,12 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line)
if (tty_line >= 0 && tty_line < p->num && p->ops && if (tty_line >= 0 && tty_line < p->num && p->ops &&
p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) { p->ops->poll_init && !p->ops->poll_init(p, tty_line, stp)) {
res = tty_driver_kref_get(p);
*line = tty_line; *line = tty_line;
break; return tty_driver_kref_get(p);
} }
} }
mutex_unlock(&tty_mutex);
return res; return NULL;
} }
EXPORT_SYMBOL_GPL(tty_find_polling_driver); EXPORT_SYMBOL_GPL(tty_find_polling_driver);
#endif #endif
@ -531,16 +529,15 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
*/ */
static struct file *tty_release_redirect(struct tty_struct *tty) static struct file *tty_release_redirect(struct tty_struct *tty)
{ {
struct file *f = NULL; guard(spinlock)(&redirect_lock);
spin_lock(&redirect_lock);
if (redirect && file_tty(redirect) == tty) { if (redirect && file_tty(redirect) == tty) {
f = redirect; struct file *f = redirect;
redirect = NULL; redirect = NULL;
return f;
} }
spin_unlock(&redirect_lock);
return f; return NULL;
} }
/** /**
@ -765,11 +762,8 @@ void __stop_tty(struct tty_struct *tty)
*/ */
void stop_tty(struct tty_struct *tty) void stop_tty(struct tty_struct *tty)
{ {
unsigned long flags; guard(spinlock_irqsave)(&tty->flow.lock);
spin_lock_irqsave(&tty->flow.lock, flags);
__stop_tty(tty); __stop_tty(tty);
spin_unlock_irqrestore(&tty->flow.lock, flags);
} }
EXPORT_SYMBOL(stop_tty); EXPORT_SYMBOL(stop_tty);
@ -796,11 +790,8 @@ void __start_tty(struct tty_struct *tty)
*/ */
void start_tty(struct tty_struct *tty) void start_tty(struct tty_struct *tty)
{ {
unsigned long flags; guard(spinlock_irqsave)(&tty->flow.lock);
spin_lock_irqsave(&tty->flow.lock, flags);
__start_tty(tty); __start_tty(tty);
spin_unlock_irqrestore(&tty->flow.lock, flags);
} }
EXPORT_SYMBOL(start_tty); EXPORT_SYMBOL(start_tty);
@ -809,7 +800,8 @@ static void tty_update_time(struct tty_struct *tty, bool mtime)
time64_t sec = ktime_get_real_seconds(); time64_t sec = ktime_get_real_seconds();
struct tty_file_private *priv; struct tty_file_private *priv;
spin_lock(&tty->files_lock); guard(spinlock)(&tty->files_lock);
list_for_each_entry(priv, &tty->tty_files, list) { list_for_each_entry(priv, &tty->tty_files, list) {
struct inode *inode = file_inode(priv->file); struct inode *inode = file_inode(priv->file);
struct timespec64 time = mtime ? inode_get_mtime(inode) : inode_get_atime(inode); struct timespec64 time = mtime ? inode_get_mtime(inode) : inode_get_atime(inode);
@ -827,7 +819,6 @@ static void tty_update_time(struct tty_struct *tty, bool mtime)
inode_set_atime(inode, sec, 0); inode_set_atime(inode, sec, 0);
} }
} }
spin_unlock(&tty->files_lock);
} }
/* /*
@ -2314,13 +2305,12 @@ static int tiocsti(struct tty_struct *tty, u8 __user *p)
*/ */
static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg) static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{ {
int err; guard(mutex)(&tty->winsize_mutex);
mutex_lock(&tty->winsize_mutex); if (copy_to_user(arg, &tty->winsize, sizeof(*arg)))
err = copy_to_user(arg, &tty->winsize, sizeof(*arg)); return -EFAULT;
mutex_unlock(&tty->winsize_mutex);
return err ? -EFAULT : 0; return 0;
} }
/** /**
@ -2335,10 +2325,10 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
{ {
struct pid *pgrp; struct pid *pgrp;
/* Lock the tty */ guard(mutex)(&tty->winsize_mutex);
mutex_lock(&tty->winsize_mutex);
if (!memcmp(ws, &tty->winsize, sizeof(*ws))) if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
goto done; return 0;
/* Signal the foreground process group */ /* Signal the foreground process group */
pgrp = tty_get_pgrp(tty); pgrp = tty_get_pgrp(tty);
@ -2347,8 +2337,7 @@ int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
put_pid(pgrp); put_pid(pgrp);
tty->winsize = *ws; tty->winsize = *ws;
done:
mutex_unlock(&tty->winsize_mutex);
return 0; return 0;
} }
EXPORT_SYMBOL(tty_do_resize); EXPORT_SYMBOL(tty_do_resize);
@ -2409,13 +2398,14 @@ static int tioccons(struct file *file)
return -EBADF; return -EBADF;
if (!(file->f_mode & FMODE_CAN_WRITE)) if (!(file->f_mode & FMODE_CAN_WRITE))
return -EINVAL; return -EINVAL;
spin_lock(&redirect_lock);
if (redirect) { guard(spinlock)(&redirect_lock);
spin_unlock(&redirect_lock);
if (redirect)
return -EBUSY; return -EBUSY;
}
redirect = get_file(file); redirect = get_file(file);
spin_unlock(&redirect_lock);
return 0; return 0;
} }
@ -3028,11 +3018,9 @@ void __do_SAK(struct tty_struct *tty)
struct task_struct *g, *p; struct task_struct *g, *p;
struct pid *session; struct pid *session;
int i; int i;
unsigned long flags;
spin_lock_irqsave(&tty->ctrl.lock, flags); scoped_guard(spinlock_irqsave, &tty->ctrl.lock)
session = get_pid(tty->ctrl.session); session = get_pid(tty->ctrl.session);
spin_unlock_irqrestore(&tty->ctrl.lock, flags);
tty_ldisc_flush(tty); tty_ldisc_flush(tty);
@ -3055,7 +3043,7 @@ void __do_SAK(struct tty_struct *tty)
PIDTYPE_SID); PIDTYPE_SID);
continue; continue;
} }
task_lock(p); guard(task_lock)(p);
i = iterate_fd(p->files, 0, this_tty, tty); i = iterate_fd(p->files, 0, this_tty, tty);
if (i != 0) { if (i != 0) {
tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n", tty_notice(tty, "SAK: killed process %d (%s): by fd#%d\n",
@ -3063,7 +3051,6 @@ void __do_SAK(struct tty_struct *tty)
group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, group_send_sig_info(SIGKILL, SEND_SIG_PRIV, p,
PIDTYPE_SID); PIDTYPE_SID);
} }
task_unlock(p);
} }
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
put_pid(session); put_pid(session);
@ -3465,9 +3452,8 @@ int tty_register_driver(struct tty_driver *driver)
goto err_unreg_char; goto err_unreg_char;
} }
mutex_lock(&tty_mutex); scoped_guard(mutex, &tty_mutex)
list_add(&driver->tty_drivers, &tty_drivers); list_add(&driver->tty_drivers, &tty_drivers);
mutex_unlock(&tty_mutex);
if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) { if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
for (i = 0; i < driver->num; i++) { for (i = 0; i < driver->num; i++) {
@ -3486,9 +3472,8 @@ int tty_register_driver(struct tty_driver *driver)
for (i--; i >= 0; i--) for (i--; i >= 0; i--)
tty_unregister_device(driver, i); tty_unregister_device(driver, i);
mutex_lock(&tty_mutex); scoped_guard(mutex, &tty_mutex)
list_del(&driver->tty_drivers); list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
err_unreg_char: err_unreg_char:
unregister_chrdev_region(dev, driver->num); unregister_chrdev_region(dev, driver->num);
@ -3507,9 +3492,8 @@ void tty_unregister_driver(struct tty_driver *driver)
{ {
unregister_chrdev_region(MKDEV(driver->major, driver->minor_start), unregister_chrdev_region(MKDEV(driver->major, driver->minor_start),
driver->num); driver->num);
mutex_lock(&tty_mutex); scoped_guard(mutex, &tty_mutex)
list_del(&driver->tty_drivers); list_del(&driver->tty_drivers);
mutex_unlock(&tty_mutex);
} }
EXPORT_SYMBOL(tty_unregister_driver); EXPORT_SYMBOL(tty_unregister_driver);