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[82.65.169.74]) by smtp.googlemail.com with ESMTPSA id p9sm242544wma.12.2020.10.19.10.07.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2020 10:07:17 -0700 (PDT) From: Jerome Brunet To: Oliver Neukum , Greg Kroah-Hartman Cc: Jerome Brunet , Kevin Hilman , linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Pascal Vizeli Subject: [PATCH] usb: cdc-acm: fix cooldown mechanism Date: Mon, 19 Oct 2020 19:07:02 +0200 Message-Id: <20201019170702.150534-1-jbrunet@baylibre.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Patchwork-Bot: notify Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Commit a4e7279cd1d1 ("cdc-acm: introduce a cool down") is causing regression if there is some USB error, such as -EPROTO. This has been reported on some samples of the Odroid-N2 using the Combee II Zibgee USB dongle. > struct acm *acm = container_of(work, struct acm, work) is incorrect in case of a delayed work and causes warnings, usually from the workqueue: > WARNING: CPU: 0 PID: 0 at kernel/workqueue.c:1474 __queue_work+0x480/0x528. When this happens, USB eventually stops working completely after a while. Also the ACM_ERROR_DELAY bit is never set, so the cooldown mechanism previously introduced cannot be triggered and acm_submit_read_urb() is never called. This changes makes the cdc-acm driver use a single delayed work, fixing the pointer arithmetic in acm_softint() and set the ACM_ERROR_DELAY when the cooldown mechanism appear to be needed. Fixes: a4e7279cd1d1 ("cdc-acm: introduce a cool down") Reported-by: Pascal Vizeli Cc: Oliver Neukum Signed-off-by: Jerome Brunet Acked-by: Oliver Neukum --- Hi, I tried to fix problem introduced by commit a4e7279cd1d1 ("cdc-acm: introduce a cool down") while keeping the original intent, or at least what I understand of it. A plain revert of the original commit also works for me. drivers/usb/class/cdc-acm.c | 12 +++++------- drivers/usb/class/cdc-acm.h | 3 +-- 2 files changed, 6 insertions(+), 9 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index f1a9043bdfe5..172cd2d21914 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -507,6 +507,7 @@ static void acm_read_bulk_callback(struct urb *urb) "%s - cooling babbling device\n", __func__); usb_mark_last_busy(acm->dev); set_bit(rb->index, &acm->urbs_in_error_delay); + set_bit(ACM_ERROR_DELAY, &acm->flags); cooldown = true; break; default: @@ -532,7 +533,7 @@ static void acm_read_bulk_callback(struct urb *urb) if (stopped || stalled || cooldown) { if (stalled) - schedule_work(&acm->work); + schedule_delayed_work(&acm->dwork, 0); else if (cooldown) schedule_delayed_work(&acm->dwork, HZ / 2); return; @@ -562,13 +563,13 @@ static void acm_write_bulk(struct urb *urb) acm_write_done(acm, wb); spin_unlock_irqrestore(&acm->write_lock, flags); set_bit(EVENT_TTY_WAKEUP, &acm->flags); - schedule_work(&acm->work); + schedule_delayed_work(&acm->dwork, 0); } static void acm_softint(struct work_struct *work) { int i; - struct acm *acm = container_of(work, struct acm, work); + struct acm *acm = container_of(work, struct acm, dwork.work); if (test_bit(EVENT_RX_STALL, &acm->flags)) { smp_mb(); /* against acm_suspend() */ @@ -584,7 +585,7 @@ static void acm_softint(struct work_struct *work) if (test_and_clear_bit(ACM_ERROR_DELAY, &acm->flags)) { for (i = 0; i < acm->rx_buflimit; i++) if (test_and_clear_bit(i, &acm->urbs_in_error_delay)) - acm_submit_read_urb(acm, i, GFP_NOIO); + acm_submit_read_urb(acm, i, GFP_KERNEL); } if (test_and_clear_bit(EVENT_TTY_WAKEUP, &acm->flags)) @@ -1352,7 +1353,6 @@ static int acm_probe(struct usb_interface *intf, acm->ctrlsize = ctrlsize; 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); @@ -1562,7 +1562,6 @@ 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); @@ -1605,7 +1604,6 @@ static int acm_suspend(struct usb_interface *intf, pm_message_t message) return 0; acm_kill_urbs(acm); - cancel_work_sync(&acm->work); cancel_delayed_work_sync(&acm->dwork); acm->urbs_in_error_delay = 0; diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index cd5e9d8ab237..b95ff769072e 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -112,8 +112,7 @@ struct acm { # 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 various purposes*/ - struct delayed_work dwork; /* for cool downs needed in error recovery */ + struct delayed_work dwork; /* work queue entry for various purposes */ 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 */