>From 8722f5ea3ce89aaffe6f63cb6986b2a2b89eb830 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oliver@xxxxxxxxxx>
Date: Wed, 3 Feb 2010 16:58:58 +0100
Subject: [PATCH] usb:cdc-acm:fix possible deadlock with multiple openers
The lock must be dropped before usb_autopm_interface_put() is called
Signed-off-by: Oliver Neukum <oliver@xxxxxxxxxx>
---
drivers/usb/class/cdc-acm.c | 11 ++++++-----
1 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 34d4eb9..e5fd3b0 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -566,7 +566,7 @@ 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;
@@ -582,8 +582,9 @@ 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;
@@ -612,18 +613,18 @@ 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);
--
1.6.4.2
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