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USB: cdc-acm: fix broken runtime suspend 

The current ACM runtime-suspend implementation is broken in several
ways:

Firstly, it buffers only the first write request being made while
suspended -- any further writes are silently dropped.

Secondly, writes being dropped also leak write urbs, which are never
reclaimed (until the device is unbound).

Thirdly, even the single buffered write is not cleared at shutdown
(which may happen before the device is resumed), something which can
lead to another urb leak as well as a PM usage-counter leak.

Fix this by implementing a delayed-write queue using urb anchors and
making sure to discard the queue properly at shutdown.

Fixes: 11ea859d64 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Reported-by: Xiao Jin <jin.xiao@intel.com>
Cc: <stable@vger.kernel.org>	# v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2014-05-26 19:23:38 +02:00 committed by Greg Kroah-Hartman
parent e144ed28be
commit 140cb81ac8
2 changed files with 23 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
drivers/usb/class/cdc-acm.c
View File

@ -573,6 +573,8 @@ static void acm_port_destruct(struct tty_port *port)
static void acm_port_shutdown(struct tty_port *port)
{
struct acm *acm = container_of(port, struct acm, port);
struct urb *urb;
struct acm_wb *wb;
int i;
dev_dbg(&acm->control->dev, "%s\n", __func__);
@ -581,6 +583,16 @@ static void acm_port_shutdown(struct tty_port *port)
if (!acm->disconnected) {
usb_autopm_get_interface(acm->control);
acm_set_control(acm, acm->ctrlout = 0);
for (;;) {
urb = usb_get_from_anchor(&acm->delayed);
if (!urb)
break;
wb = urb->context;
wb->use = 0;
usb_autopm_put_interface_async(acm->control);
}
usb_kill_urb(acm->ctrlurb);
for (i = 0; i < ACM_NW; i++)
usb_kill_urb(acm->wb[i].urb);
@ -648,12 +660,9 @@ static int acm_tty_write(struct tty_struct *tty,
usb_autopm_get_interface_async(acm->control);
if (acm->susp_count) {
if (!acm->delayed_wb)
acm->delayed_wb = wb;
else
usb_autopm_put_interface_async(acm->control);
usb_anchor_urb(wb->urb, &acm->delayed);
spin_unlock_irqrestore(&acm->write_lock, flags);
return count; /* A white lie */
return count;
}
usb_mark_last_busy(acm->dev);
@ -1269,6 +1278,7 @@ static int acm_probe(struct usb_interface *intf,
acm->bInterval = epread->bInterval;
tty_port_init(&acm->port);
acm->port.ops = &acm_port_ops;
init_usb_anchor(&acm->delayed);
buf = usb_alloc_coherent(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma);
if (!buf) {
@ -1539,7 +1549,7 @@ static int acm_suspend(struct usb_interface *intf, pm_message_t message)
static int acm_resume(struct usb_interface *intf)
{
struct acm *acm = usb_get_intfdata(intf);
struct acm_wb *wb;
struct urb *urb;
int rv = 0;
spin_lock_irq(&acm->read_lock);
@ -1551,10 +1561,12 @@ static int acm_resume(struct usb_interface *intf)
if (test_bit(ASYNCB_INITIALIZED, &acm->port.flags)) {
rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);
if (acm->delayed_wb) {
wb = acm->delayed_wb;
acm->delayed_wb = NULL;
acm_start_wb(acm, wb);
for (;;) {
urb = usb_get_from_anchor(&acm->delayed);
if (!urb)
break;
acm_start_wb(acm, urb->context);
}
/*

2
drivers/usb/class/cdc-acm.h
View File

@ -120,7 +120,7 @@ struct acm {
unsigned int throttled:1; /* actually throttled */
unsigned int throttle_req:1; /* throttle requested */
u8 bInterval;
struct acm_wb *delayed_wb; /* write queued for a device about to be woken */
struct usb_anchor delayed; /* writes queued for a device about to be woken */
};
#define CDC_DATA_INTERFACE_TYPE 0x0a