[PATCH v2 0/5] can: esd_usb: Fixes and improvements

[PATCH v2 0/5] can: esd_usb: Fixes and improvements

[Stefan Mätje]

The first patch fixes a condition where the esd_usb CAN driver
may not detect connected CAN-USB devices correctly after a
reboot. This patch was already presented on the list before
starting this series and changes due to that feedback are
integrated.

References:
https://lore.kernel.org/linux-can/d7fd564775351ea8a60a6ada83a0368a99ea6b19.camel@esd.eu/

The second patch fixes situations where the the handling of TX
context objects for each sent CAN frame could go out of sync
with the acknowledged or erroneous TX jobs and then lose free
TX context objects. This could lead to the driver incapable of
sending frames.

The third patch adds TX FIFO watermark to eliminate occasional
error messages and significantly reduce the number of calls to
netif_start_queue() and netif_stop_queue().

The forth patch makes some error messages also print the error
code to achieve a higher significance. Removes also a duplicate
message and makes the register / unregister messages symmetric.

The fifth patch avoids emitting any error messages during the 
disconnect of CAN-USB devices or the driver unload.

Previous versions:
 v1: https://lore.kernel.org/linux-can/20250811210611.3233202-1-stefan.maetje@esd.eu/

Changes in v2:
  - Withdraw "can: esd_usb: Fix possible calls to kfree() with NULL".
  - Reworked now first patch:
    - Functions esd_usb_req_version() and esd_usb_recv_version()
      now allocate their own transfer buffers.
    - Check whether the announced message size fits into received
      data block.
  - Second patch: Added a Fixes tag
  - Third patch: Added a Fixes tag
  - Forth patch:
    - Convert all occurrences of error status prints to use
      "ERR_PTR(err)" instead of printing the decimal value
      of "err".
    - Rename retval to err in esd_usb_read_bulk_callback() to
      make the naming of error status variables consistent
      with all other functions.

Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
Stefan Mätje (5):
  can: esd_usb: Fix not detecting version reply in probe routine
  can: esd_usb: Fix handling of TX context objects
  can: esd_usb: Add watermark handling for TX jobs
  can: esd_usb: Rework display of error messages
  can: esd_usb: Avoid errors triggered from USB disconnect

 drivers/net/can/usb/esd_usb.c | 238 ++++++++++++++++++++++++----------
 1 file changed, 171 insertions(+), 67 deletions(-)


base-commit: 0e6639c8505d70e821bc27f951a0ff6303f10d4d
-- 
2.34.1

[PATCH v2 1/5] can: esd_usb: Fix not detecting version reply in probe routine

[Stefan Mätje]

This patch fixes some problems in the esd_usb_probe routine that render
the CAN interface unusable.

The probe routine sends a version request message to the USB device to
receive a version reply with the number of CAN ports and the hard-
& firmware versions. Then for each CAN port a CAN netdev is registered.

The previous code assumed that the version reply would be received
immediately. But if the driver was reloaded without power cycling the
USB device (i. e. on a reboot) there could already be other incoming
messages in the USB buffers. These would be in front of the version
reply and need to be skipped.

In the previous code these problems were present:
- Only one usb_bulk_msg() read was done into a buffer of
  sizeof(union esd_usb_msg) which is smaller than ESD_USB_RX_BUFFER_SIZE
  which could lead to an overflow error from the USB stack.
- The first bytes of the received data were taken without checking for
  the message type. This could lead to zero detected CAN interfaces.

To mitigate these problems:
- Moved the code to send the version request message into a standalone
  function esd_usb_req_version().
- Added a function esd_usb_recv_version() using a transfer buffer
  with ESD_USB_RX_BUFFER_SIZE. It reads and skips incoming "esd_usb_msg"
  messages until a version reply message is found. This is evaluated to
  return the count of CAN ports and version information.
- The data drain loop is limited by a maximum # of bytes to read from
  the device based on its internal buffer sizes and a timeout
  ESD_USB_DRAIN_TIMEOUT_MS.

This version of the patch incorporates changes recommended on the
linux-can list for a very first version.

References:
https://lore.kernel.org/linux-can/d7fd564775351ea8a60a6ada83a0368a99ea6b19.camel@esd.eu/#r

Fixes: 80662d943075 ("can: esd_usb: Add support for esd CAN-USB/3")
Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 145 ++++++++++++++++++++++++++--------
 1 file changed, 110 insertions(+), 35 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 27a3818885c2..fb0563582326 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -3,7 +3,7 @@
  * CAN driver for esd electronics gmbh CAN-USB/2, CAN-USB/3 and CAN-USB/Micro
  *
  * Copyright (C) 2010-2012 esd electronic system design gmbh, Matthias Fuchs <socketcan@esd.eu>
- * Copyright (C) 2022-2024 esd electronics gmbh, Frank Jungclaus <frank.jungclaus@esd.eu>
+ * Copyright (C) 2022-2025 esd electronics gmbh, Frank Jungclaus <frank.jungclaus@esd.eu>
  */
 
 #include <linux/can.h>
@@ -44,6 +44,9 @@ MODULE_LICENSE("GPL v2");
 #define ESD_USB_CMD_TS			5 /* also used for TS_REPLY */
 #define ESD_USB_CMD_IDADD		6 /* also used for IDADD_REPLY */
 
+/* esd version message name size */
+#define ESD_USB_FW_NAME_SZ 16
+
 /* esd CAN message flags - dlc field */
 #define ESD_USB_RTR	BIT(4)
 #define ESD_USB_NO_BRS	BIT(4)
@@ -95,6 +98,7 @@ MODULE_LICENSE("GPL v2");
 #define ESD_USB_RX_BUFFER_SIZE		1024
 #define ESD_USB_MAX_RX_URBS		4
 #define ESD_USB_MAX_TX_URBS		16 /* must be power of 2 */
+#define ESD_USB_DRAIN_TIMEOUT_MS	100
 
 /* Modes for CAN-USB/3, to be used for esd_usb_3_set_baudrate_msg_x.mode */
 #define ESD_USB_3_BAUDRATE_MODE_DISABLE		0 /* remove from bus */
@@ -131,7 +135,7 @@ struct esd_usb_version_reply_msg {
 	u8 nets;
 	u8 features;
 	__le32 version;
-	u8 name[16];
+	u8 name[ESD_USB_FW_NAME_SZ];
 	__le32 rsvd;
 	__le32 ts;
 };
@@ -625,17 +629,106 @@ static int esd_usb_send_msg(struct esd_usb *dev, union esd_usb_msg *msg)
 			    1000);
 }
 
-static int esd_usb_wait_msg(struct esd_usb *dev,
-			    union esd_usb_msg *msg)
+static int esd_usb_req_version(struct esd_usb *dev)
 {
-	int actual_length;
+	union esd_usb_msg *msg;
+	int err;
 
-	return usb_bulk_msg(dev->udev,
-			    usb_rcvbulkpipe(dev->udev, 1),
-			    msg,
-			    sizeof(*msg),
-			    &actual_length,
-			    1000);
+	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	msg->hdr.cmd = ESD_USB_CMD_VERSION;
+	msg->hdr.len = sizeof(struct esd_usb_version_msg) / sizeof(u32); /* # of 32bit words */
+	msg->version.rsvd = 0;
+	msg->version.flags = 0;
+	msg->version.drv_version = 0;
+
+	err = esd_usb_send_msg(dev, msg);
+	kfree(msg);
+	return err;
+}
+
+static int esd_usb_recv_version(struct esd_usb *dev)
+{
+	/* Device hardware has 2 RX buffers with ESD_USB_RX_BUFFER_SIZE, * 4 to give some slack. */
+	const int max_drain_bytes = (4 * ESD_USB_RX_BUFFER_SIZE);
+	unsigned long end_jiffies;
+	void *rx_buf;
+	int cnt_other = 0;
+	int cnt_ts = 0;
+	int cnt_vs = 0;
+	int len_sum = 0;
+	int attempt = 0;
+	int err;
+
+	rx_buf = kmalloc(ESD_USB_RX_BUFFER_SIZE, GFP_KERNEL);
+	if (!rx_buf)
+		return -ENOMEM;
+
+	end_jiffies = jiffies + msecs_to_jiffies(ESD_USB_DRAIN_TIMEOUT_MS);
+	do {
+		int actual_length;
+		int pos;
+
+		err = usb_bulk_msg(dev->udev,
+				   usb_rcvbulkpipe(dev->udev, 1),
+				   rx_buf,
+				   ESD_USB_RX_BUFFER_SIZE,
+				   &actual_length,
+				   ESD_USB_DRAIN_TIMEOUT_MS);
+		dev_dbg(&dev->udev->dev, "AT %d, LEN %d, ERR %d\n", attempt, actual_length, err);
+		++attempt;
+		if (err)
+			goto bail;
+		if (actual_length == 0)
+			continue;
+
+		err = -ENOENT;
+		len_sum += actual_length;
+		pos = 0;
+		while (pos < actual_length - sizeof(struct esd_usb_header_msg)) {
+			union esd_usb_msg *p_msg;
+
+			p_msg = (union esd_usb_msg *)(rx_buf + pos);
+
+			pos += p_msg->hdr.len * sizeof(u32); /* convert to # of bytes */
+			if (pos > actual_length) {
+				dev_err(&dev->udev->dev, "format error\n");
+				err = -EPROTO;
+				goto bail;
+			}
+
+			switch (p_msg->hdr.cmd) {
+			case ESD_USB_CMD_VERSION:
+				++cnt_vs;
+				dev->net_count = min(p_msg->version_reply.nets, ESD_USB_MAX_NETS);
+				dev->version = le32_to_cpu(p_msg->version_reply.version);
+				err = 0;
+				dev_dbg(&dev->udev->dev, "TS 0x%08x, V 0x%08x, N %u, F 0x%02x, %.*s\n",
+					le32_to_cpu(p_msg->version_reply.ts),
+					le32_to_cpu(p_msg->version_reply.version),
+					p_msg->version_reply.nets,
+					p_msg->version_reply.features,
+					ESD_USB_FW_NAME_SZ, p_msg->version_reply.name);
+				break;
+			case ESD_USB_CMD_TS:
+				++cnt_ts;
+				dev_dbg(&dev->udev->dev, "TS 0x%08x\n",
+					le32_to_cpu(p_msg->rx.ts));
+				break;
+			default:
+				++cnt_other;
+				dev_dbg(&dev->udev->dev, "HDR %d\n", p_msg->hdr.cmd);
+				break;
+			}
+		}
+	} while (cnt_vs == 0 && len_sum < max_drain_bytes && time_before(jiffies, end_jiffies));
+bail:
+	dev_dbg(&dev->udev->dev, "RC=%d; ATT=%d, TS=%d, VS=%d, O=%d, B=%d\n",
+		err, attempt, cnt_ts, cnt_vs, cnt_other, len_sum);
+	kfree(rx_buf);
+	return err;
 }
 
 static int esd_usb_setup_rx_urbs(struct esd_usb *dev)
@@ -1273,13 +1366,12 @@ static int esd_usb_probe(struct usb_interface *intf,
 			 const struct usb_device_id *id)
 {
 	struct esd_usb *dev;
-	union esd_usb_msg *msg;
 	int i, err;
 
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (!dev) {
 		err = -ENOMEM;
-		goto done;
+		goto bail;
 	}
 
 	dev->udev = interface_to_usbdev(intf);
@@ -1288,34 +1380,19 @@ static int esd_usb_probe(struct usb_interface *intf,
 
 	usb_set_intfdata(intf, dev);
 
-	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
-	if (!msg) {
-		err = -ENOMEM;
-		goto free_msg;
-	}
-
 	/* query number of CAN interfaces (nets) */
-	msg->hdr.cmd = ESD_USB_CMD_VERSION;
-	msg->hdr.len = sizeof(struct esd_usb_version_msg) / sizeof(u32); /* # of 32bit words */
-	msg->version.rsvd = 0;
-	msg->version.flags = 0;
-	msg->version.drv_version = 0;
-
-	err = esd_usb_send_msg(dev, msg);
+	err = esd_usb_req_version(dev);
 	if (err < 0) {
 		dev_err(&intf->dev, "sending version message failed\n");
-		goto free_msg;
+		goto bail;
 	}
 
-	err = esd_usb_wait_msg(dev, msg);
+	err = esd_usb_recv_version(dev);
 	if (err < 0) {
 		dev_err(&intf->dev, "no version message answer\n");
-		goto free_msg;
+		goto bail;
 	}
 
-	dev->net_count = (int)msg->version_reply.nets;
-	dev->version = le32_to_cpu(msg->version_reply.version);
-
 	if (device_create_file(&intf->dev, &dev_attr_firmware))
 		dev_err(&intf->dev,
 			"Couldn't create device file for firmware\n");
@@ -1332,11 +1409,9 @@ static int esd_usb_probe(struct usb_interface *intf,
 	for (i = 0; i < dev->net_count; i++)
 		esd_usb_probe_one_net(intf, i);
 
-free_msg:
-	kfree(msg);
+bail:
 	if (err)
 		kfree(dev);
-done:
 	return err;
 }
 
-- 
2.34.1

[PATCH v2 2/5] can: esd_usb: Fix handling of TX context objects

[Stefan Mätje]

For each TX CAN frame submitted to the USB device the driver saves the
echo skb index in struct esd_tx_urb_context context objects. If the
driver runs out of free context objects CAN transmission stops.

This patch fixes some spots where such context objects are not freed
correctly.

In esd_usb_tx_done_msg() the check for netif_device_present() is moved
after the identification and release of TX context and the release of
the echo skb. This is allowed even if netif_device_present() would
return false because the mentioned operations don't touch the device
itself but only free local acquired resources. This keeps the context
handling with the acknowledged TX jobs in sync.

In esd_usb_start_xmit() a check is performed to see whether a context
object could be allocated. Added a netif_stop_queue() there before the
function is aborted. This makes sure the network queue is stopped and
avoids getting tons of log messages in a situation without free TX
objects. The adjacent log message now also prints the active jobs
counter making a cross check between active jobs and "no free context"
condition possible.

In esd_usb_start_xmit() the error handling of usb_submit_urb() missed to
free the context object together with the echo skb and decreasing the
job count.

Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index fb0563582326..4ba6b6abd928 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -460,9 +460,6 @@ static void esd_usb_tx_done_msg(struct esd_usb_net_priv *priv,
 	struct net_device *netdev = priv->netdev;
 	struct esd_tx_urb_context *context;
 
-	if (!netif_device_present(netdev))
-		return;
-
 	context = &priv->tx_contexts[msg->txdone.hnd & (ESD_USB_MAX_TX_URBS - 1)];
 
 	if (!msg->txdone.status) {
@@ -478,6 +475,9 @@ static void esd_usb_tx_done_msg(struct esd_usb_net_priv *priv,
 	context->echo_index = ESD_USB_MAX_TX_URBS;
 	atomic_dec(&priv->active_tx_jobs);
 
+	if (!netif_device_present(netdev))
+		return;
+
 	netif_wake_queue(netdev);
 }
 
@@ -975,9 +975,11 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 		}
 	}
 
-	/* This may never happen */
+	/* This should never happen */
 	if (!context) {
-		netdev_warn(netdev, "couldn't find free context\n");
+		netdev_warn(netdev, "No free context. Jobs: %d\n",
+			    atomic_read(&priv->active_tx_jobs));
+		netif_stop_queue(netdev);
 		ret = NETDEV_TX_BUSY;
 		goto releasebuf;
 	}
@@ -1008,6 +1010,8 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 	if (err) {
 		can_free_echo_skb(netdev, context->echo_index, NULL);
 
+		/* Release used context on error */
+		context->echo_index = ESD_USB_MAX_TX_URBS;
 		atomic_dec(&priv->active_tx_jobs);
 		usb_unanchor_urb(urb);
 
-- 
2.34.1

[PATCH v2 3/5] can: esd_usb: Add watermark handling for TX jobs

[Stefan Mätje]

The driver tried to keep as much CAN frames as possible submitted to the
USB device (ESD_USB_MAX_TX_URBS). This has led to occasional "No free
context" error messages in high load situations like with
"cangen -g 0 -p 10 canX".

This patch now calls netif_stop_queue() already if the number of active
jobs reaches ESD_USB_TX_URBS_HI_WM which is < ESD_USB_MAX_TX_URBS.
The netif_start_queue() is called in esd_usb_tx_done_msg() only if
the number of active jobs is <= ESD_USB_TX_URBS_LO_WM.

This change eliminates the occasional error messages and significantly
reduces the number of calls to netif_start_queue() and
netif_stop_queue().

The watermark limits have been chosen with the CAN-USB/Micro in mind to
not to compromise its TX throughput. This device is running on USB 1.1
only with its 1ms USB polling cycle where a ESD_USB_TX_URBS_LO_WM
value below 9 decreases the TX throughput.

Fixes: 96d8e90382dc ("can: Add driver for esd CAN-USB/2 device")
Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 4ba6b6abd928..98ab7c836880 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -98,6 +98,8 @@ MODULE_LICENSE("GPL v2");
 #define ESD_USB_RX_BUFFER_SIZE		1024
 #define ESD_USB_MAX_RX_URBS		4
 #define ESD_USB_MAX_TX_URBS		16 /* must be power of 2 */
+#define ESD_USB_TX_URBS_HI_WM		((15 * ESD_USB_MAX_TX_URBS) / 16)
+#define ESD_USB_TX_URBS_LO_WM		((9 * ESD_USB_MAX_TX_URBS) / 16)
 #define ESD_USB_DRAIN_TIMEOUT_MS	100
 
 /* Modes for CAN-USB/3, to be used for esd_usb_3_set_baudrate_msg_x.mode */
@@ -478,7 +480,8 @@ static void esd_usb_tx_done_msg(struct esd_usb_net_priv *priv,
 	if (!netif_device_present(netdev))
 		return;
 
-	netif_wake_queue(netdev);
+	if (atomic_read(&priv->active_tx_jobs) <= ESD_USB_TX_URBS_LO_WM)
+		netif_wake_queue(netdev);
 }
 
 static void esd_usb_read_bulk_callback(struct urb *urb)
@@ -987,7 +990,7 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 	context->priv = priv;
 	context->echo_index = i;
 
-	/* hnd must not be 0 - MSB is stripped in txdone handling */
+	/* hnd must not be 0 - MSB is stripped in TX done handling */
 	msg->tx.hnd = BIT(31) | i; /* returned in TX done message */
 
 	usb_fill_bulk_urb(urb, dev->udev, usb_sndbulkpipe(dev->udev, 2), buf,
@@ -1002,8 +1005,8 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 
 	atomic_inc(&priv->active_tx_jobs);
 
-	/* Slow down tx path */
-	if (atomic_read(&priv->active_tx_jobs) >= ESD_USB_MAX_TX_URBS)
+	/* Slow down TX path */
+	if (atomic_read(&priv->active_tx_jobs) >= ESD_USB_TX_URBS_HI_WM)
 		netif_stop_queue(netdev);
 
 	err = usb_submit_urb(urb, GFP_ATOMIC);
-- 
2.34.1

[PATCH v2 4/5] can: esd_usb: Rework display of error messages

[Stefan Mätje]

- esd_usb_open(): Get rid of duplicate "couldn't start device: %d\n"
  message already printed from esd_usb_start().
- Fix duplicate printout of network device name when network device
  is registered. Add an unregister message for the network device
  as counterpart to the register message.
- Added the printout of error codes together with the error messages
  in esd_usb_close() and some in esd_usb_probe(). The additional error
  codes should lead to a better understanding what is really going
  wrong.
- Convert all occurrences of error status prints to use "ERR_PTR(err)"
  instead of printing the decimal value of "err".
- Rename retval to err in esd_usb_read_bulk_callback() to make the
  naming of error status variables consistent with all other functions.

Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 40 +++++++++++++++++++----------------
 1 file changed, 22 insertions(+), 18 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 98ab7c836880..8e6688f10451 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -9,6 +9,7 @@
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/error.h>
+#include <linux/err.h>
 #include <linux/ethtool.h>
 #include <linux/module.h>
 #include <linux/netdevice.h>
@@ -487,7 +488,7 @@ static void esd_usb_tx_done_msg(struct esd_usb_net_priv *priv,
 static void esd_usb_read_bulk_callback(struct urb *urb)
 {
 	struct esd_usb *dev = urb->context;
-	int retval;
+	int err;
 	int pos = 0;
 	int i;
 
@@ -503,7 +504,7 @@ static void esd_usb_read_bulk_callback(struct urb *urb)
 
 	default:
 		dev_info(dev->udev->dev.parent,
-			 "Rx URB aborted (%d)\n", urb->status);
+			 "Rx URB aborted (%pe)\n", ERR_PTR(urb->status));
 		goto resubmit_urb;
 	}
 
@@ -546,15 +547,15 @@ static void esd_usb_read_bulk_callback(struct urb *urb)
 			  urb->transfer_buffer, ESD_USB_RX_BUFFER_SIZE,
 			  esd_usb_read_bulk_callback, dev);
 
-	retval = usb_submit_urb(urb, GFP_ATOMIC);
-	if (retval == -ENODEV) {
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err == -ENODEV) {
 		for (i = 0; i < dev->net_count; i++) {
 			if (dev->nets[i])
 				netif_device_detach(dev->nets[i]->netdev);
 		}
-	} else if (retval) {
+	} else if (err) {
 		dev_err(dev->udev->dev.parent,
-			"failed resubmitting read bulk urb: %d\n", retval);
+			"failed resubmitting read bulk urb: %pe\n", ERR_PTR(err));
 	}
 }
 
@@ -579,7 +580,7 @@ static void esd_usb_write_bulk_callback(struct urb *urb)
 		return;
 
 	if (urb->status)
-		netdev_info(netdev, "Tx URB aborted (%d)\n", urb->status);
+		netdev_info(netdev, "Tx URB aborted (%pe)\n", ERR_PTR(urb->status));
 
 	netif_trans_update(netdev);
 }
@@ -854,7 +855,7 @@ static int esd_usb_start(struct esd_usb_net_priv *priv)
 	if (err == -ENODEV)
 		netif_device_detach(netdev);
 	if (err)
-		netdev_err(netdev, "couldn't start device: %d\n", err);
+		netdev_err(netdev, "couldn't start device: %pe\n", ERR_PTR(err));
 
 	kfree(msg);
 	return err;
@@ -896,7 +897,6 @@ static int esd_usb_open(struct net_device *netdev)
 	/* finally start device */
 	err = esd_usb_start(priv);
 	if (err) {
-		netdev_warn(netdev, "couldn't start device: %d\n", err);
 		close_candev(netdev);
 		return err;
 	}
@@ -1023,7 +1023,7 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 		if (err == -ENODEV)
 			netif_device_detach(netdev);
 		else
-			netdev_warn(netdev, "failed tx_urb %d\n", err);
+			netdev_warn(netdev, "failed tx_urb %pe\n", ERR_PTR(err));
 
 		goto releasebuf;
 	}
@@ -1051,6 +1051,7 @@ static int esd_usb_close(struct net_device *netdev)
 {
 	struct esd_usb_net_priv *priv = netdev_priv(netdev);
 	union esd_usb_msg *msg;
+	int err;
 	int i;
 
 	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
@@ -1064,8 +1065,9 @@ static int esd_usb_close(struct net_device *netdev)
 	msg->filter.option = ESD_USB_ID_ENABLE; /* start with segment 0 */
 	for (i = 0; i <= ESD_USB_MAX_ID_SEGMENT; i++)
 		msg->filter.mask[i] = 0;
-	if (esd_usb_send_msg(priv->usb, msg) < 0)
-		netdev_err(netdev, "sending idadd message failed\n");
+	err = esd_usb_send_msg(priv->usb, msg);
+	if (err < 0)
+		netdev_err(netdev, "sending idadd message failed: %pe\n", ERR_PTR(err));
 
 	/* set CAN controller to reset mode */
 	msg->hdr.len = sizeof(struct esd_usb_set_baudrate_msg) / sizeof(u32); /* # of 32bit words */
@@ -1073,8 +1075,9 @@ static int esd_usb_close(struct net_device *netdev)
 	msg->setbaud.net = priv->index;
 	msg->setbaud.rsvd = 0;
 	msg->setbaud.baud = cpu_to_le32(ESD_USB_NO_BAUDRATE);
-	if (esd_usb_send_msg(priv->usb, msg) < 0)
-		netdev_err(netdev, "sending setbaud message failed\n");
+	err = esd_usb_send_msg(priv->usb, msg);
+	if (err < 0)
+		netdev_err(netdev, "sending setbaud message failed: %pe\n", ERR_PTR(err));
 
 	priv->can.state = CAN_STATE_STOPPED;
 
@@ -1351,14 +1354,14 @@ static int esd_usb_probe_one_net(struct usb_interface *intf, int index)
 
 	err = register_candev(netdev);
 	if (err) {
-		dev_err(&intf->dev, "couldn't register CAN device: %d\n", err);
+		dev_err(&intf->dev, "couldn't register CAN device: %pe\n", ERR_PTR(err));
 		free_candev(netdev);
 		err = -ENOMEM;
 		goto done;
 	}
 
 	dev->nets[index] = priv;
-	netdev_info(netdev, "device %s registered\n", netdev->name);
+	netdev_info(netdev, "registered\n");
 
 done:
 	return err;
@@ -1390,13 +1393,13 @@ static int esd_usb_probe(struct usb_interface *intf,
 	/* query number of CAN interfaces (nets) */
 	err = esd_usb_req_version(dev);
 	if (err < 0) {
-		dev_err(&intf->dev, "sending version message failed\n");
+		dev_err(&intf->dev, "sending version message failed: %pe\n", ERR_PTR(err));
 		goto bail;
 	}
 
 	err = esd_usb_recv_version(dev);
 	if (err < 0) {
-		dev_err(&intf->dev, "no version message answer\n");
+		dev_err(&intf->dev, "no version message answer: %pe\n", ERR_PTR(err));
 		goto bail;
 	}
 
@@ -1439,6 +1442,7 @@ static void esd_usb_disconnect(struct usb_interface *intf)
 		for (i = 0; i < dev->net_count; i++) {
 			if (dev->nets[i]) {
 				netdev = dev->nets[i]->netdev;
+				netdev_info(netdev, "unregister\n");
 				unregister_netdev(netdev);
 				free_candev(netdev);
 			}
-- 
2.34.1

[PATCH v2 5/5] can: esd_usb: Avoid errors triggered from USB disconnect

[Stefan Mätje]

The USB stack calls during disconnect the esd_usb_disconnect() callback.
esd_usb_disconnect() calls netdev_unregister() for each network which
in turn calls the net_device_ops::ndo_stop callback esd_usb_close() if
the net device is up.

The esd_usb_close() callback tries to disable all CAN Ids and to reset
the CAN controller of the device sending appropriate control messages.

Sending these messages in .disconnect() is moot and always fails because
either the device is gone or the USB communication is already torn down
by the USB stack in the course of a rmmod operation.

This patch moves the code that sends these control messages to a new
function esd_usb_stop() which is approximately the counterpart of
esd_usb_start() to make code structure less convoluted.

It then changes esd_usb_close() not to send the control messages at
all if the ndo_stop() callback is executed from the USB .disconnect()
callback. A new flag in_usb_disconnect is added to the struct esd_usb
device structure to mark this condition which is checked by
esd_usb_close() whether to skip the send operations in esd_usb_start().

Signed-off-by: Stefan Mätje <stefan.maetje@esd.eu>
---
 drivers/net/can/usb/esd_usb.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/net/can/usb/esd_usb.c b/drivers/net/can/usb/esd_usb.c
index 8e6688f10451..0196394c5986 100644
--- a/drivers/net/can/usb/esd_usb.c
+++ b/drivers/net/can/usb/esd_usb.c
@@ -281,6 +281,7 @@ struct esd_usb {
 	int net_count;
 	u32 version;
 	int rxinitdone;
+	int in_usb_disconnect;
 	void *rxbuf[ESD_USB_MAX_RX_URBS];
 	dma_addr_t rxbuf_dma[ESD_USB_MAX_RX_URBS];
 };
@@ -1047,9 +1048,9 @@ static netdev_tx_t esd_usb_start_xmit(struct sk_buff *skb,
 	return ret;
 }
 
-static int esd_usb_close(struct net_device *netdev)
+/* Stop interface */
+static int esd_usb_stop(struct esd_usb_net_priv *priv)
 {
-	struct esd_usb_net_priv *priv = netdev_priv(netdev);
 	union esd_usb_msg *msg;
 	int err;
 	int i;
@@ -1066,8 +1067,10 @@ static int esd_usb_close(struct net_device *netdev)
 	for (i = 0; i <= ESD_USB_MAX_ID_SEGMENT; i++)
 		msg->filter.mask[i] = 0;
 	err = esd_usb_send_msg(priv->usb, msg);
-	if (err < 0)
-		netdev_err(netdev, "sending idadd message failed: %pe\n", ERR_PTR(err));
+	if (err < 0) {
+		netdev_err(priv->netdev, "sending idadd message failed: %pe\n", ERR_PTR(err));
+		goto bail;
+	}
 
 	/* set CAN controller to reset mode */
 	msg->hdr.len = sizeof(struct esd_usb_set_baudrate_msg) / sizeof(u32); /* # of 32bit words */
@@ -1077,7 +1080,23 @@ static int esd_usb_close(struct net_device *netdev)
 	msg->setbaud.baud = cpu_to_le32(ESD_USB_NO_BAUDRATE);
 	err = esd_usb_send_msg(priv->usb, msg);
 	if (err < 0)
-		netdev_err(netdev, "sending setbaud message failed: %pe\n", ERR_PTR(err));
+		netdev_err(priv->netdev, "sending setbaud message failed: %pe\n", ERR_PTR(err));
+
+bail:
+	kfree(msg);
+
+	return err;
+}
+
+static int esd_usb_close(struct net_device *netdev)
+{
+	struct esd_usb_net_priv *priv = netdev_priv(netdev);
+	int err = 0;
+
+	if (!priv->usb->in_usb_disconnect) {
+		/* It's moot to try this in usb_disconnect()! */
+		err = esd_usb_stop(priv);
+	}
 
 	priv->can.state = CAN_STATE_STOPPED;
 
@@ -1085,9 +1104,7 @@ static int esd_usb_close(struct net_device *netdev)
 
 	close_candev(netdev);
 
-	kfree(msg);
-
-	return 0;
+	return err;
 }
 
 static const struct net_device_ops esd_usb_netdev_ops = {
@@ -1439,6 +1456,7 @@ static void esd_usb_disconnect(struct usb_interface *intf)
 	usb_set_intfdata(intf, NULL);
 
 	if (dev) {
+		dev->in_usb_disconnect = 1;
 		for (i = 0; i < dev->net_count; i++) {
 			if (dev->nets[i]) {
 				netdev = dev->nets[i]->netdev;
-- 
2.34.1