From: Vitor Soares <vitor.soares(a)toradex.com>
When the mcp251xfd_start_xmit() function fails, the driver stops
processing messages, and the interrupt routine does not return,
running indefinitely even after killing the running application.
Error messages:
[ 441.298819] mcp251xfd spi2.0 can0: ERROR in mcp251xfd_start_xmit: -16
[ 441.306498] mcp251xfd spi2.0 can0: Transmit Event FIFO buffer not empty. (seq=0x000017c7, tef_tail=0x000017cf, tef_head=0x000017d0, tx_head=0x000017d3).
... and repeat forever.
The issue can be triggered when multiple devices share the same
SPI interface. And there is concurrent access to the bus.
The problem occurs because tx_ring->head increments even if
mcp251xfd_start_xmit() fails. Consequently, the driver skips one
TX package while still expecting a response in
mcp251xfd_handle_tefif_one().
This patch resolves the issue by decreasing tx_ring->head if
mcp251xfd_start_xmit() fails. With the fix, if we trigger the issue and
the err = -EBUSY, the driver returns NETDEV_TX_BUSY. The network stack
retries to transmit the message.
Otherwise, it prints an error and discards the message.
Fixes: 55e5b97f003e ("can: mcp25xxfd: add driver for Microchip MCP25xxFD SPI CAN")
Cc: stable(a)vger.kernel.org
Signed-off-by: Vitor Soares <vitor.soares(a)toradex.com>
---
V2->V3:
- Add tx_dropped stats.
- netdev_sent_queue() only if can_put_echo_skb() succeed.
V1->V2:
- Return NETDEV_TX_BUSY if mcp251xfd_tx_obj_write() == -EBUSY.
- Rework the commit message to address the change above.
- Change can_put_echo_skb() to be called after mcp251xfd_tx_obj_write() succeed.
Otherwise, we get Kernel NULL pointer dereference error.
drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c | 34 ++++++++++++--------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
index 160528d3cc26..146c44e47c60 100644
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-tx.c
@@ -166,6 +166,7 @@ netdev_tx_t mcp251xfd_start_xmit(struct sk_buff *skb,
struct net_device *ndev)
{
struct mcp251xfd_priv *priv = netdev_priv(ndev);
+ struct net_device_stats *stats = &ndev->stats;
struct mcp251xfd_tx_ring *tx_ring = priv->tx;
struct mcp251xfd_tx_obj *tx_obj;
unsigned int frame_len;
@@ -181,25 +182,32 @@ netdev_tx_t mcp251xfd_start_xmit(struct sk_buff *skb,
tx_obj = mcp251xfd_get_tx_obj_next(tx_ring);
mcp251xfd_tx_obj_from_skb(priv, tx_obj, skb, tx_ring->head);
- /* Stop queue if we occupy the complete TX FIFO */
tx_head = mcp251xfd_get_tx_head(tx_ring);
- tx_ring->head++;
- if (mcp251xfd_get_tx_free(tx_ring) == 0)
- netif_stop_queue(ndev);
-
frame_len = can_skb_get_frame_len(skb);
- err = can_put_echo_skb(skb, ndev, tx_head, frame_len);
- if (!err)
- netdev_sent_queue(priv->ndev, frame_len);
+
+ tx_ring->head++;
err = mcp251xfd_tx_obj_write(priv, tx_obj);
- if (err)
- goto out_err;
+ if (err) {
+ tx_ring->head--;
- return NETDEV_TX_OK;
+ if (err == -EBUSY)
+ return NETDEV_TX_BUSY;
- out_err:
- netdev_err(priv->ndev, "ERROR in %s: %d\n", __func__, err);
+ stats->tx_dropped++;
+
+ if (net_ratelimit())
+ netdev_err(priv->ndev,
+ "ERROR in %s: %d\n", __func__, err);
+ } else {
+ err = can_put_echo_skb(skb, ndev, tx_head, frame_len);
+ if (!err)
+ netdev_sent_queue(priv->ndev, frame_len);
+
+ /* Stop queue if we occupy the complete TX FIFO */
+ if (mcp251xfd_get_tx_free(tx_ring) == 0)
+ netif_stop_queue(ndev);
+ }
return NETDEV_TX_OK;
}
--
2.34.1
The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x 680d11f6e5427b6af1321932286722d24a8b16c1
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2024042925-enrich-charbroil-ce36@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..
Possible dependencies:
680d11f6e542 ("udp: preserve the connected status if only UDP cmsg")
5298953e742d ("udp6: don't make extra copies of iflow")
42dcfd850e51 ("udp6: allow SO_MARK ctrl msg to affect routing")
3df98d79215a ("lsm,selinux: pass flowi_common instead of flowi to the LSM hooks")
e94ee171349d ("xfrm: Use correct address family in xfrm_state_find")
5eff06902394 ("ipv4: fill fl4_icmp_{type,code} in ping_v4_sendmsg")
6abde0b24122 ("crypto/chtls: IPv6 support for inline TLS")
ed52f2c608c9 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 680d11f6e5427b6af1321932286722d24a8b16c1 Mon Sep 17 00:00:00 2001
From: Yick Xie <yick.xie(a)gmail.com>
Date: Fri, 19 Apr 2024 01:06:10 +0800
Subject: [PATCH] udp: preserve the connected status if only UDP cmsg
If "udp_cmsg_send()" returned 0 (i.e. only UDP cmsg),
"connected" should not be set to 0. Otherwise it stops
the connected socket from using the cached route.
Fixes: 2e8de8576343 ("udp: add gso segment cmsg")
Signed-off-by: Yick Xie <yick.xie(a)gmail.com>
Cc: stable(a)vger.kernel.org
Reviewed-by: Willem de Bruijn <willemb(a)google.com>
Link: https://lore.kernel.org/r/20240418170610.867084-1-yick.xie@gmail.com
Signed-off-by: Jakub Kicinski <kuba(a)kernel.org>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index c02bf011d4a6..420905be5f30 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1123,16 +1123,17 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
if (msg->msg_controllen) {
err = udp_cmsg_send(sk, msg, &ipc.gso_size);
- if (err > 0)
+ if (err > 0) {
err = ip_cmsg_send(sk, msg, &ipc,
sk->sk_family == AF_INET6);
+ connected = 0;
+ }
if (unlikely(err < 0)) {
kfree(ipc.opt);
return err;
}
if (ipc.opt)
free = 1;
- connected = 0;
}
if (!ipc.opt) {
struct ip_options_rcu *inet_opt;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8b1dd7f51249..1a4cccdd40c9 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1474,9 +1474,11 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
ipc6.opt = opt;
err = udp_cmsg_send(sk, msg, &ipc6.gso_size);
- if (err > 0)
+ if (err > 0) {
err = ip6_datagram_send_ctl(sock_net(sk), sk, msg, fl6,
&ipc6);
+ connected = false;
+ }
if (err < 0) {
fl6_sock_release(flowlabel);
return err;
@@ -1488,7 +1490,6 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
}
if (!(opt->opt_nflen|opt->opt_flen))
opt = NULL;
- connected = false;
}
if (!opt) {
opt = txopt_get(np);