This is a note to let you know that I've just added the patch titled
cdc-acm: introduce a cool down
to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From a4e7279cd1d19f48f0af2a10ed020febaa9ac092 Mon Sep 17 00:00:00 2001
From: Oliver Neukum oneukum@suse.com Date: Wed, 15 Apr 2020 17:13:58 +0200 Subject: cdc-acm: introduce a cool down
Immediate submission in case of a babbling device can lead to a busy loop. Introducing a delayed work.
Signed-off-by: Oliver Neukum oneukum@suse.com Cc: stable stable@vger.kernel.org Tested-by: Jonas Karlsson jonas.karlsson@actia.se Link: https://lore.kernel.org/r/20200415151358.32664-2-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/class/cdc-acm.c | 30 ++++++++++++++++++++++++++++-- drivers/usb/class/cdc-acm.h | 5 ++++- 2 files changed, 32 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 4ef68e6671aa..ded8d93834ca 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -412,9 +412,12 @@ static void acm_ctrl_irq(struct urb *urb)
exit: retval = usb_submit_urb(urb, GFP_ATOMIC); - if (retval && retval != -EPERM) + if (retval && retval != -EPERM && retval != -ENODEV) dev_err(&acm->control->dev, "%s - usb_submit_urb failed: %d\n", __func__, retval); + else + dev_vdbg(&acm->control->dev, + "control resubmission terminated %d\n", retval); }
static int acm_submit_read_urb(struct acm *acm, int index, gfp_t mem_flags) @@ -430,6 +433,8 @@ static int acm_submit_read_urb(struct acm *acm, int index, gfp_t mem_flags) dev_err(&acm->data->dev, "urb %d failed submission with %d\n", index, res); + } else { + dev_vdbg(&acm->data->dev, "intended failure %d\n", res); } set_bit(index, &acm->read_urbs_free); return res; @@ -471,6 +476,7 @@ static void acm_read_bulk_callback(struct urb *urb) int status = urb->status; bool stopped = false; bool stalled = false; + bool cooldown = false;
dev_vdbg(&acm->data->dev, "got urb %d, len %d, status %d\n", rb->index, urb->actual_length, status); @@ -497,6 +503,14 @@ static void acm_read_bulk_callback(struct urb *urb) __func__, status); stopped = true; break; + case -EOVERFLOW: + case -EPROTO: + dev_dbg(&acm->data->dev, + "%s - cooling babbling device\n", __func__); + usb_mark_last_busy(acm->dev); + set_bit(rb->index, &acm->urbs_in_error_delay); + cooldown = true; + break; default: dev_dbg(&acm->data->dev, "%s - nonzero urb status received: %d\n", @@ -518,9 +532,11 @@ static void acm_read_bulk_callback(struct urb *urb) */ smp_mb__after_atomic();
- if (stopped || stalled) { + if (stopped || stalled || cooldown) { if (stalled) schedule_work(&acm->work); + else if (cooldown) + schedule_delayed_work(&acm->dwork, HZ / 2); return; }
@@ -567,6 +583,12 @@ static void acm_softint(struct work_struct *work) } }
+ if (test_and_clear_bit(ACM_ERROR_DELAY, &acm->flags)) { + for (i = 0; i < ACM_NR; i++) + if (test_and_clear_bit(i, &acm->urbs_in_error_delay)) + acm_submit_read_urb(acm, i, GFP_NOIO); + } + if (test_and_clear_bit(EVENT_TTY_WAKEUP, &acm->flags)) tty_port_tty_wakeup(&acm->port); } @@ -1333,6 +1355,7 @@ static int acm_probe(struct usb_interface *intf, acm->readsize = readsize; acm->rx_buflimit = num_rx_buf; INIT_WORK(&acm->work, acm_softint); + INIT_DELAYED_WORK(&acm->dwork, acm_softint); init_waitqueue_head(&acm->wioctl); spin_lock_init(&acm->write_lock); spin_lock_init(&acm->read_lock); @@ -1542,6 +1565,7 @@ static void acm_disconnect(struct usb_interface *intf)
acm_kill_urbs(acm); cancel_work_sync(&acm->work); + cancel_delayed_work_sync(&acm->dwork);
tty_unregister_device(acm_tty_driver, acm->minor);
@@ -1584,6 +1608,8 @@ static int acm_suspend(struct usb_interface *intf, pm_message_t message)
acm_kill_urbs(acm); cancel_work_sync(&acm->work); + cancel_delayed_work_sync(&acm->dwork); + acm->urbs_in_error_delay = 0;
return 0; } diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index ca1c026382c2..cd5e9d8ab237 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -109,8 +109,11 @@ struct acm { # define EVENT_TTY_WAKEUP 0 # define EVENT_RX_STALL 1 # define ACM_THROTTLED 2 +# define ACM_ERROR_DELAY 3 + unsigned long urbs_in_error_delay; /* these need to be restarted after a delay */ 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 various purposes*/ + struct delayed_work dwork; /* for cool downs needed in error recovery */ unsigned int ctrlin; /* input control lines (DCD, DSR, RI, break, overruns) */ unsigned int ctrlout; /* output control lines (DTR, RTS) */ struct async_icount iocount; /* counters for control line changes */