From: Peter Hurley Date: Wed, 5 Nov 2014 17:12:53 +0000 (-0500) Subject: tty: Don't take tty_mutex for tty count changes X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=0911261d4cb6;p=linux-beck.git tty: Don't take tty_mutex for tty count changes Holding tty_mutex is no longer required to serialize changes to the tty_count or to prevent concurrent opens of closing ttys; tty_lock() is sufficient. Reviewed-by: Alan Cox Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index ea8c6cae8d12..e59de81c39a9 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -1804,10 +1804,6 @@ int tty_release(struct inode *inode, struct file *filp) * each iteration we avoid any problems. */ while (1) { - /* Guard against races with tty->count changes elsewhere and - opens on /dev/tty */ - - mutex_lock(&tty_mutex); tty_lock_pair(tty, o_tty); tty_closing = tty->count <= 1; o_tty_closing = o_tty && @@ -1840,7 +1836,6 @@ int tty_release(struct inode *inode, struct file *filp) printk(KERN_WARNING "%s: %s: read/write wait queue active!\n", __func__, tty_name(tty, buf)); tty_unlock_pair(tty, o_tty); - mutex_unlock(&tty_mutex); schedule(); } @@ -1891,7 +1886,6 @@ int tty_release(struct inode *inode, struct file *filp) read_unlock(&tasklist_lock); } - mutex_unlock(&tty_mutex); tty_unlock_pair(tty, o_tty); /* At this point, the tty->count == 0 should ensure a dead tty cannot be re-opened by a racing opener */