From: "Ahmed S. Darwish" <ahmed.darwish@xxxxxxxxx> 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit ded5006667318c06df875609535176bd33f243a1 upstream. Upon receiving a hardware event with the BUS_RESET flag set, the driver kills all of its anchored URBs and resets all of its transmit URB contexts. Unfortunately it does so under the context of URB completion handler `kvaser_usb_read_bulk_callback()', which is often called in an atomic context. While the device is flooded with many received error packets, usb_kill_urb() typically sleeps/reschedules till the transfer request of each killed URB in question completes, leading to the sleep in atomic bug. [3] In v2 submission of the original driver patch [1], it was stated that the URBs kill and tx contexts reset was needed since we don't receive any tx acknowledgments later and thus such resources will be locked down forever. Fortunately this is no longer needed since an earlier bugfix in this patch series is now applied: all tx URB contexts are reset upon CAN channel close. [2] Moreover, a BUS_RESET is now treated _exactly_ like a BUS_OFF event, which is the recommended handling method advised by the device manufacturer. [1] http://article.gmane.org/gmane.linux.network/239442 http://www.webcitation.org/6Vr2yagAQ [2] can: kvaser_usb: Reset all URB tx contexts upon channel close 889b77f7fd2bcc922493d73a4c51d8a851505815 [3] Stacktrace: <IRQ> [<ffffffff8158de87>] dump_stack+0x45/0x57 [<ffffffff8158b60c>] __schedule_bug+0x41/0x4f [<ffffffff815904b1>] __schedule+0x5f1/0x700 [<ffffffff8159360a>] ? _raw_spin_unlock_irqrestore+0xa/0x10 [<ffffffff81590684>] schedule+0x24/0x70 [<ffffffff8147d0a5>] usb_kill_urb+0x65/0xa0 [<ffffffff81077970>] ? prepare_to_wait_event+0x110/0x110 [<ffffffff8147d7d8>] usb_kill_anchored_urbs+0x48/0x80 [<ffffffffa01f4028>] kvaser_usb_unlink_tx_urbs+0x18/0x50 [kvaser_usb] [<ffffffffa01f45d0>] kvaser_usb_rx_error+0xc0/0x400 [kvaser_usb] [<ffffffff8108b14a>] ? vprintk_default+0x1a/0x20 [<ffffffffa01f5241>] kvaser_usb_read_bulk_callback+0x4c1/0x5f0 [kvaser_usb] [<ffffffff8147a73e>] __usb_hcd_giveback_urb+0x5e/0xc0 [<ffffffff8147a8a1>] usb_hcd_giveback_urb+0x41/0x110 [<ffffffffa0008748>] finish_urb+0x98/0x180 [ohci_hcd] [<ffffffff810cd1a7>] ? acct_account_cputime+0x17/0x20 [<ffffffff81069f65>] ? local_clock+0x15/0x30 [<ffffffffa000a36b>] ohci_work+0x1fb/0x5a0 [ohci_hcd] [<ffffffff814fbb31>] ? process_backlog+0xb1/0x130 [<ffffffffa000cd5b>] ohci_irq+0xeb/0x270 [ohci_hcd] [<ffffffff81479fc1>] usb_hcd_irq+0x21/0x30 [<ffffffff8108bfd3>] handle_irq_event_percpu+0x43/0x120 [<ffffffff8108c0ed>] handle_irq_event+0x3d/0x60 [<ffffffff8108ec84>] handle_fasteoi_irq+0x74/0x110 [<ffffffff81004dfd>] handle_irq+0x1d/0x30 [<ffffffff81004727>] do_IRQ+0x57/0x100 [<ffffffff8159482a>] common_interrupt+0x6a/0x6a Signed-off-by: Ahmed S. Darwish <ahmed.darwish@xxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- drivers/net/can/usb/kvaser_usb.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c index 63fb90b006ba..ccdc4cdc496f 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -654,11 +654,6 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev, priv = dev->nets[channel]; stats = &priv->netdev->stats; - if (status & M16C_STATE_BUS_RESET) { - kvaser_usb_unlink_tx_urbs(priv); - return; - } - skb = alloc_can_err_skb(priv->netdev, &cf); if (!skb) { stats->rx_dropped++; @@ -669,7 +664,7 @@ static void kvaser_usb_rx_error(const struct kvaser_usb *dev, netdev_dbg(priv->netdev, "Error status: 0x%02x\n", status); - if (status & M16C_STATE_BUS_OFF) { + if (status & (M16C_STATE_BUS_OFF | M16C_STATE_BUS_RESET)) { cf->can_id |= CAN_ERR_BUSOFF; priv->can.can_stats.bus_off++; -- 2.2.2 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html