mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
um: convert count_lock to mutex, fix a race in line_open()
If two processes are opening the same line, the second to get into line_open() will decide that it doesn't need to do anything (correctly) or wait for anything. The latter, unfortunately, is incorrect - the first opener might not be through yet. We need to have exclusion covering the entire line_init(), including the blocking parts. Moreover, the next patch will need to widen the exclusion on mconsole side of things, also including the blocking bits, so let's just convert that sucker to mutex... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
parent
43574c1afe
commit
d8c215adbf
4 changed files with 12 additions and 20 deletions
|
@ -409,7 +409,7 @@ int line_open(struct line *lines, struct tty_struct *tty)
|
|||
struct line *line = &lines[tty->index];
|
||||
int err = -ENODEV;
|
||||
|
||||
spin_lock(&line->count_lock);
|
||||
mutex_lock(&line->count_lock);
|
||||
if (!line->valid)
|
||||
goto out_unlock;
|
||||
|
||||
|
@ -421,10 +421,9 @@ int line_open(struct line *lines, struct tty_struct *tty)
|
|||
tty->driver_data = line;
|
||||
line->tty = tty;
|
||||
|
||||
spin_unlock(&line->count_lock);
|
||||
err = enable_chan(line);
|
||||
if (err) /* line_close() will be called by our caller */
|
||||
return err;
|
||||
goto out_unlock;
|
||||
|
||||
INIT_DELAYED_WORK(&line->task, line_timer_cb);
|
||||
|
||||
|
@ -435,11 +434,8 @@ int line_open(struct line *lines, struct tty_struct *tty)
|
|||
|
||||
chan_window_size(&line->chan_list, &tty->winsize.ws_row,
|
||||
&tty->winsize.ws_col);
|
||||
|
||||
return 0;
|
||||
|
||||
out_unlock:
|
||||
spin_unlock(&line->count_lock);
|
||||
mutex_unlock(&line->count_lock);
|
||||
return err;
|
||||
}
|
||||
|
||||
|
@ -459,7 +455,7 @@ void line_close(struct tty_struct *tty, struct file * filp)
|
|||
/* We ignore the error anyway! */
|
||||
flush_buffer(line);
|
||||
|
||||
spin_lock(&line->count_lock);
|
||||
mutex_lock(&line->count_lock);
|
||||
BUG_ON(!line->valid);
|
||||
|
||||
if (--line->count)
|
||||
|
@ -468,17 +464,13 @@ void line_close(struct tty_struct *tty, struct file * filp)
|
|||
line->tty = NULL;
|
||||
tty->driver_data = NULL;
|
||||
|
||||
spin_unlock(&line->count_lock);
|
||||
|
||||
if (line->sigio) {
|
||||
unregister_winch(tty);
|
||||
line->sigio = 0;
|
||||
}
|
||||
|
||||
return;
|
||||
|
||||
out_unlock:
|
||||
spin_unlock(&line->count_lock);
|
||||
mutex_unlock(&line->count_lock);
|
||||
}
|
||||
|
||||
void close_lines(struct line *lines, int nlines)
|
||||
|
@ -495,7 +487,7 @@ static int setup_one_line(struct line *lines, int n, char *init,
|
|||
struct line *line = &lines[n];
|
||||
int err = -EINVAL;
|
||||
|
||||
spin_lock(&line->count_lock);
|
||||
mutex_lock(&line->count_lock);
|
||||
|
||||
if (line->count) {
|
||||
*error_out = "Device is already open";
|
||||
|
@ -510,7 +502,7 @@ static int setup_one_line(struct line *lines, int n, char *init,
|
|||
}
|
||||
err = 0;
|
||||
out:
|
||||
spin_unlock(&line->count_lock);
|
||||
mutex_unlock(&line->count_lock);
|
||||
return err;
|
||||
}
|
||||
|
||||
|
@ -609,13 +601,13 @@ int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
|
|||
|
||||
line = &lines[dev];
|
||||
|
||||
spin_lock(&line->count_lock);
|
||||
mutex_lock(&line->count_lock);
|
||||
if (!line->valid)
|
||||
CONFIG_CHUNK(str, size, n, "none", 1);
|
||||
else if (line->tty == NULL)
|
||||
CONFIG_CHUNK(str, size, n, line->init_str, 1);
|
||||
else n = chan_config_string(&line->chan_list, str, size, error_out);
|
||||
spin_unlock(&line->count_lock);
|
||||
mutex_unlock(&line->count_lock);
|
||||
|
||||
return n;
|
||||
}
|
||||
|
|
|
@ -32,7 +32,7 @@ struct line_driver {
|
|||
|
||||
struct line {
|
||||
struct tty_struct *tty;
|
||||
spinlock_t count_lock;
|
||||
struct mutex count_lock;
|
||||
unsigned long count;
|
||||
int valid;
|
||||
|
||||
|
|
|
@ -201,7 +201,7 @@ static int ssl_init(void)
|
|||
serial_lines[i].valid = 1;
|
||||
}
|
||||
spin_lock_init(&serial_lines[i].lock);
|
||||
spin_lock_init(&serial_lines[i].count_lock);
|
||||
mutex_init(&serial_lines[i].count_lock);
|
||||
serial_lines[i].driver = &driver;
|
||||
}
|
||||
ssl_driver = register_lines(&driver, &ssl_ops, serial_lines,
|
||||
|
|
|
@ -173,7 +173,7 @@ static int stdio_init(void)
|
|||
vts[i].valid = 1;
|
||||
}
|
||||
spin_lock_init(&vts[i].lock);
|
||||
spin_lock_init(&vts[i].count_lock);
|
||||
mutex_init(&vts[i].count_lock);
|
||||
vts[i].driver = &driver;
|
||||
}
|
||||
console_driver = register_lines(&driver, &console_ops, vts,
|
||||
|
|
Loading…
Reference in a new issue