usb: cdc-acm: drain writes on close
Add a mechanism to let the write queue drain naturally before closing the TTY, rather than always losing that data. There is a timeout, so it can't wait too long. Provide missing locking inside acm_wb_is_avail(); it matters more now. Note, this presumes an earlier patch was applied, removing a call to this routine where the lock was held. Slightly improved diagnostics on write URB completion, so we can tell when a write URB gets killed and, if so, how much data it wrote first ... and so that I/O path is normally silent (and can't much change timings). Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
parent
934da4635c
commit
e5fbab51b4
|
@ -51,6 +51,7 @@
|
||||||
*/
|
*/
|
||||||
|
|
||||||
#undef DEBUG
|
#undef DEBUG
|
||||||
|
#undef VERBOSE_DEBUG
|
||||||
|
|
||||||
#include <linux/kernel.h>
|
#include <linux/kernel.h>
|
||||||
#include <linux/errno.h>
|
#include <linux/errno.h>
|
||||||
|
@ -70,6 +71,9 @@
|
||||||
|
|
||||||
#include "cdc-acm.h"
|
#include "cdc-acm.h"
|
||||||
|
|
||||||
|
|
||||||
|
#define ACM_CLOSE_TIMEOUT 15 /* seconds to let writes drain */
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* Version Information
|
* Version Information
|
||||||
*/
|
*/
|
||||||
|
@ -85,6 +89,12 @@ static DEFINE_MUTEX(open_mutex);
|
||||||
|
|
||||||
#define ACM_READY(acm) (acm && acm->dev && acm->used)
|
#define ACM_READY(acm) (acm && acm->dev && acm->used)
|
||||||
|
|
||||||
|
#ifdef VERBOSE_DEBUG
|
||||||
|
#define verbose 1
|
||||||
|
#else
|
||||||
|
#define verbose 0
|
||||||
|
#endif
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* Functions for ACM control messages.
|
* Functions for ACM control messages.
|
||||||
*/
|
*/
|
||||||
|
@ -136,11 +146,14 @@ static int acm_wb_alloc(struct acm *acm)
|
||||||
static int acm_wb_is_avail(struct acm *acm)
|
static int acm_wb_is_avail(struct acm *acm)
|
||||||
{
|
{
|
||||||
int i, n;
|
int i, n;
|
||||||
|
unsigned long flags;
|
||||||
|
|
||||||
n = ACM_NW;
|
n = ACM_NW;
|
||||||
|
spin_lock_irqsave(&acm->write_lock, flags);
|
||||||
for (i = 0; i < ACM_NW; i++) {
|
for (i = 0; i < ACM_NW; i++) {
|
||||||
n -= acm->wb[i].use;
|
n -= acm->wb[i].use;
|
||||||
}
|
}
|
||||||
|
spin_unlock_irqrestore(&acm->write_lock, flags);
|
||||||
return n;
|
return n;
|
||||||
}
|
}
|
||||||
|
|
||||||
|
@ -467,22 +480,28 @@ urbs:
|
||||||
/* data interface wrote those outgoing bytes */
|
/* data interface wrote those outgoing bytes */
|
||||||
static void acm_write_bulk(struct urb *urb)
|
static void acm_write_bulk(struct urb *urb)
|
||||||
{
|
{
|
||||||
struct acm *acm;
|
|
||||||
struct acm_wb *wb = urb->context;
|
struct acm_wb *wb = urb->context;
|
||||||
|
struct acm *acm = wb->instance;
|
||||||
|
|
||||||
dbg("Entering acm_write_bulk with status %d", urb->status);
|
if (verbose || urb->status
|
||||||
|
|| (urb->actual_length != urb->transfer_buffer_length))
|
||||||
|
dev_dbg(&acm->data->dev, "tx %d/%d bytes -- > %d\n",
|
||||||
|
urb->actual_length,
|
||||||
|
urb->transfer_buffer_length,
|
||||||
|
urb->status);
|
||||||
|
|
||||||
acm = wb->instance;
|
|
||||||
acm_write_done(acm, wb);
|
acm_write_done(acm, wb);
|
||||||
if (ACM_READY(acm))
|
if (ACM_READY(acm))
|
||||||
schedule_work(&acm->work);
|
schedule_work(&acm->work);
|
||||||
|
else
|
||||||
|
wake_up_interruptible(&acm->drain_wait);
|
||||||
}
|
}
|
||||||
|
|
||||||
static void acm_softint(struct work_struct *work)
|
static void acm_softint(struct work_struct *work)
|
||||||
{
|
{
|
||||||
struct acm *acm = container_of(work, struct acm, work);
|
struct acm *acm = container_of(work, struct acm, work);
|
||||||
dbg("Entering acm_softint.");
|
|
||||||
|
|
||||||
|
dev_vdbg(&acm->data->dev, "tx work\n");
|
||||||
if (!ACM_READY(acm))
|
if (!ACM_READY(acm))
|
||||||
return;
|
return;
|
||||||
tty_wakeup(acm->tty);
|
tty_wakeup(acm->tty);
|
||||||
|
@ -603,6 +622,8 @@ static void acm_tty_unregister(struct acm *acm)
|
||||||
kfree(acm);
|
kfree(acm);
|
||||||
}
|
}
|
||||||
|
|
||||||
|
static int acm_tty_chars_in_buffer(struct tty_struct *tty);
|
||||||
|
|
||||||
static void acm_tty_close(struct tty_struct *tty, struct file *filp)
|
static void acm_tty_close(struct tty_struct *tty, struct file *filp)
|
||||||
{
|
{
|
||||||
struct acm *acm = tty->driver_data;
|
struct acm *acm = tty->driver_data;
|
||||||
|
@ -617,6 +638,13 @@ static void acm_tty_close(struct tty_struct *tty, struct file *filp)
|
||||||
if (acm->dev) {
|
if (acm->dev) {
|
||||||
usb_autopm_get_interface(acm->control);
|
usb_autopm_get_interface(acm->control);
|
||||||
acm_set_control(acm, acm->ctrlout = 0);
|
acm_set_control(acm, acm->ctrlout = 0);
|
||||||
|
|
||||||
|
/* try letting the last writes drain naturally */
|
||||||
|
wait_event_interruptible_timeout(acm->drain_wait,
|
||||||
|
(ACM_NW == acm_wb_is_avail(acm))
|
||||||
|
|| !acm->dev,
|
||||||
|
ACM_CLOSE_TIMEOUT * HZ);
|
||||||
|
|
||||||
usb_kill_urb(acm->ctrlurb);
|
usb_kill_urb(acm->ctrlurb);
|
||||||
for (i = 0; i < ACM_NW; i++)
|
for (i = 0; i < ACM_NW; i++)
|
||||||
usb_kill_urb(acm->wb[i].urb);
|
usb_kill_urb(acm->wb[i].urb);
|
||||||
|
@ -1047,6 +1075,7 @@ skip_normal_probe:
|
||||||
acm->urb_task.data = (unsigned long) acm;
|
acm->urb_task.data = (unsigned long) acm;
|
||||||
INIT_WORK(&acm->work, acm_softint);
|
INIT_WORK(&acm->work, acm_softint);
|
||||||
INIT_WORK(&acm->waker, acm_waker);
|
INIT_WORK(&acm->waker, acm_waker);
|
||||||
|
init_waitqueue_head(&acm->drain_wait);
|
||||||
spin_lock_init(&acm->throttle_lock);
|
spin_lock_init(&acm->throttle_lock);
|
||||||
spin_lock_init(&acm->write_lock);
|
spin_lock_init(&acm->write_lock);
|
||||||
spin_lock_init(&acm->read_lock);
|
spin_lock_init(&acm->read_lock);
|
||||||
|
|
|
@ -113,6 +113,7 @@ struct acm {
|
||||||
struct usb_cdc_line_coding line; /* bits, stop, parity */
|
struct usb_cdc_line_coding line; /* bits, stop, parity */
|
||||||
struct work_struct work; /* work queue entry for line discipline waking up */
|
struct work_struct work; /* work queue entry for line discipline waking up */
|
||||||
struct work_struct waker;
|
struct work_struct waker;
|
||||||
|
wait_queue_head_t drain_wait; /* close processing */
|
||||||
struct tasklet_struct urb_task; /* rx processing */
|
struct tasklet_struct urb_task; /* rx processing */
|
||||||
spinlock_t throttle_lock; /* synchronize throtteling and read callback */
|
spinlock_t throttle_lock; /* synchronize throtteling and read callback */
|
||||||
unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */
|
unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */
|
||||||
|
|
Loading…
Reference in New Issue