[PATCH net-next v3 04/12] net: mctp: usb: Improve IN endpoint status handling
From: Jeremy Kerr <jk@codeconstruct.com.au>
Date: 2026-07-08 09:59:20
Also in:
linux-usb
Subsystem:
management component transport protocol (mctp), networking drivers, the rest · Maintainers:
Jeremy Kerr, Matt Johnston, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Currently, we give-up on all non-zero status values on our IN/rx urb, and do not re-queue the urb. This will stall the driver, and prevent any further receive. Instead, attempt a re-queue on transient errors, with a max of ten successive failures. Handle EPIPE specially, by scheduling a usb_clear_halt() in non-atomic context. Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> --- v3: - improved IN urb status handling was introduced in v2, but now split to a separate change, via sashiko feedback - now with usb_clear_halt on EPIPE. --- drivers/net/mctp/mctp-usb.c | 70 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 64 insertions(+), 6 deletions(-)
diff --git a/drivers/net/mctp/mctp-usb.c b/drivers/net/mctp/mctp-usb.c
index 9e5c64e76e4a..82de4d5967db 100644
--- a/drivers/net/mctp/mctp-usb.c
+++ b/drivers/net/mctp/mctp-usb.c@@ -32,6 +32,9 @@ struct mctp_usb { struct urb *tx_urb; struct urb *rx_urb; + int in_err_count; + int in_err_orig; + bool clear_halt; /* enforces atomic access to rx_stopped and requeuing the retry work */ spinlock_t rx_lock;
@@ -158,27 +161,66 @@ static int mctp_usb_rx_queue(struct mctp_usb *mctp_usb, gfp_t gfp) return 0; } +static const unsigned int rx_err_max = 10; + static void mctp_usb_in_complete(struct urb *urb) { struct mctp_usb *mctp_usb = urb->context; struct net_device *netdev = mctp_usb->netdev; + unsigned long flags; int status; status = urb->status; switch (status) { - default: - netdev_dbg(netdev, "unexpected rx urb status: %d\n", status); - fallthrough; case -ENOENT: case -ECONNRESET: case -ESHUTDOWN: - case -EPROTO: + /* device shutdown, don't resubmit */ mctp_usblib_rx_cancel(&mctp_usb->rx); return; + + case -EPIPE: + /* endpoint stall: clear halt, which will cause a resubmit */ + + if (!mctp_usb->in_err_count++) + mctp_usb->in_err_orig = status; + if (mctp_usb->in_err_count >= rx_err_max) { + netdev_err(netdev, "excessive stalls from IN EP\n"); + return; + } + + mctp_usb->clear_halt = true; + spin_lock_irqsave(&mctp_usb->rx_lock, flags); + if (!mctp_usb->rx_stopped) + schedule_delayed_work(&mctp_usb->rx_retry_work, + RX_RETRY_DELAY); + spin_unlock_irqrestore(&mctp_usb->rx_lock, flags); + mctp_usblib_rx_cancel(&mctp_usb->rx); + return; + + default: + netdev_dbg(netdev, "unexpected rx urb status: %d\n", status); + fallthrough; + case -ETIME: + case -EPROTO: + case -EILSEQ: + case -EOVERFLOW: + /* possibly transient; record first failure, resubmit */ + mctp_usblib_rx_cancel(&mctp_usb->rx); + if (!mctp_usb->in_err_count++) + mctp_usb->in_err_orig = status; + if (mctp_usb->in_err_count >= rx_err_max) { + netdev_err(netdev, + "excessive errors from IN EP, first: %d\n", + mctp_usb->in_err_orig); + return; + } + break; + case 0: - mctp_usblib_rx_complete(netdev, &mctp_usb->rx, - urb->actual_length); + mctp_usblib_rx_complete(netdev, &mctp_usb->rx, urb->actual_length); + mctp_usb->in_err_count = 0; break; }
@@ -189,6 +231,20 @@ static void mctp_usb_rx_retry_work(struct work_struct *work) { struct mctp_usb *mctp_usb = container_of(work, struct mctp_usb, rx_retry_work.work); + int rc; + + /* We are only called when rx completions are suspended */ + if (mctp_usb->clear_halt) { + int pipe = usb_rcvbulkpipe(mctp_usb->usbdev, mctp_usb->ep_in); + + rc = usb_clear_halt(mctp_usb->usbdev, pipe); + if (rc) { + netdev_err(mctp_usb->netdev, + "can't clear IN EP halt: %d\n", rc); + return; + } + mctp_usb->clear_halt = false; + } mctp_usb_rx_queue(mctp_usb, GFP_KERNEL); }
@@ -198,6 +254,8 @@ static int mctp_usb_open(struct net_device *dev) struct mctp_usb *mctp_usb = netdev_priv(dev); WRITE_ONCE(mctp_usb->rx_stopped, false); + mctp_usb->clear_halt = false; + mctp_usb->in_err_count = 0; netif_start_queue(dev);
--
2.47.3