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Commit 2b626dc1 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman
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USB: cdc-acm: fix possible deadlock with multiple openers 



The lock must be dropped before usb_autopm_interface_put() is called

Signed-off-by: default avatarOliver Neukum <oliver@neukum.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent d7e18a9f

drivers/usb/class/cdc-acm.c

+6 −5
Original line number Diff line number Diff line
@@ -553,7 +553,7 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp) 


	acm = acm_table[tty->index];

	if (!acm || !acm->dev)

		goto err_out;

		goto out;

	else

		rv = 0;
@@ -569,8 +569,9 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp) 


	mutex_lock(&acm->mutex);

	if (acm->port.count++) {

		mutex_unlock(&acm->mutex);

		usb_autopm_put_interface(acm->control);

		goto done;

		goto out;

	}



	acm->ctrlurb->dev = acm->dev;
@@ -599,18 +600,18 @@ static int acm_tty_open(struct tty_struct *tty, struct file *filp) 
	set_bit(ASYNCB_INITIALIZED, &acm->port.flags);

	rv = tty_port_block_til_ready(&acm->port, tty, filp);

	tasklet_schedule(&acm->urb_task);

done:



	mutex_unlock(&acm->mutex);

err_out:

out:

	mutex_unlock(&open_mutex);

	return rv;



full_bailout:

	usb_kill_urb(acm->ctrlurb);

bail_out:

	usb_autopm_put_interface(acm->control);

	acm->port.count--;

	mutex_unlock(&acm->mutex);

	usb_autopm_put_interface(acm->control);

early_bail:

	mutex_unlock(&open_mutex);

	tty_port_tty_set(&acm->port, NULL);