[PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races

[PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races

[Cunhao Lu via B4 Relay]

On a production robot using a LubanCat-5IO with an RK3588, the CAN TX
queue remained stopped while RX continued, and subsequent sends returned
ENOBUFS. The interface still reported ERROR-ACTIVE, with neither a
hardware bus-off condition nor a pending TX request.

During CAN traffic, the driver also repeatedly reported an inconsistent
TX echo state:

  rockchip_canfd fea60000.can can0: rkcanfd_tx_tail_is_eff:
  echo_skb[0]=NULL tx_head=0x00060f7d tx_tail=0x00060f7c

The Rockchip CAN-FD driver completes transmissions by matching
self-received frames with entries in the echo skb ring. A race between its
transmit and completion paths can expose a partially updated echo entry,
dereference an skb queued for NAPI, or stop the TX queue without a later
completion to wake it.

While testing the echo-loss fix with fault injection, I discovered a
separate race between bus-off restart and device close.

Rockchip currently cancels restart_work in close_candev(), after freeing
the IRQ, disabling RX offload and stopping the controller. A concurrent
restart can re-enable the controller and interrupts after IRQ teardown,
and requeue timestamp work that accesses registers after runtime suspend
has disabled the controller clocks.

The CAN core skips scheduling or starting recovery when its
netif_running() check observes the interface down. A new
close_candev_cancel_restart_sync() helper lets Rockchip wait for any
restart already in progress before tearing down resources.
The final close_candev() call retains cancellation and echo cleanup.

Rockchip restart masks the device's interrupts and drains active IRQ
handlers without disabling the shared interrupt line. It also drains
timestamp work before reinitializing the controller and timecounter.
The Rockchip IRQ handler stays suspended until initialization is complete.
Timestamp locking prevents workers from rearming after deactivation and
keeps timestamp conversions consistent with timecounter updates.

The bus-off path drains TX submission and RX-side echo users before
publishing BUS_OFF. Consumed RX FIFO entries are dropped while TX is
disabled to prevent self-transmitted frames from reaching ordinary RX.
Startup serializes carrier restoration, IRQ resumption and queue wake
with a new bus-off. The series also fixes RX offload cleanup when
request_irq() fails during open.

The following issues remain outside this series:

- Races in the Rockchip bus error counter cache.
- Incomplete runtime PM clock cleanup during removal or failed registration.
- Missing explicit interrupt-mask write completion before free_irq() in
  the Rockchip close path.

When I have time, I will send separate patches to fix them one by one.

Hardware testing used a LubanCat-5IO running Linux 6.18 PREEMPT and
PREEMPT_RT kernels with v7 and the applicable prerequisites backported.
Tests on each kernel covered 600 seconds of bidirectional classic CAN
traffic, plus CAN FD and CAN FD+BRS. Local echo and both software and
hardware TX timestamps were also verified.

All 1,000 socket-close iterations passed. Instrumentation captured
1,150 cases where the last TX skb of a closed socket was destroyed,
all after releasing tx_lock and with IRQs enabled.

All 200 injected echo clone failures dropped the frame without
submitting TX, advancing tx_head or adding BQL bytes; subsequent sends
succeeded after removing the injection. BUSY, occupied slots, missing
echo skbs and invalid indices were also tested, along with automatic and
manual recovery from hardware bus-off triggered by bitrate mismatches.
All passed.

Test-only instrumentation captured 20 restart/close and 20 close/FIFO
interleavings. No timestamp worker ran during about 300 seconds after
close, and no WARN/Oops, deadlocks or persistent TX stalls were observed
during CAN testing.

Signed-off-by: Cunhao Lu <1579567540@qq.com>
---
Changes in v8:
- Merge the previously submitted Rockchip TX fixes, with TX serialization
  before the retry fix.
- Move retained-skb handling and the missing-echo guard into the echo
  failure fix, using the original skb as the frame-data source.
- Establish the TX/RX critical sections and caller-held helper locking in
  the TX serialization patch, covering queue updates, TX diagnostics and
  RX pending checks, with assertions for command writes.
- Reuse those critical sections in the bus-off/restart lifecycle patch.
- Rebase onto the latest testing branch in the mkl/linux-can-next repository.
- Link to the Rockchip TX fixes:
  https://lore.kernel.org/linux-can/tencent_E25C9BE6689264E4138A464803B810FDFD09@qq.com
- Link to v7:
  https://patch.msgid.link/20261106-rockchip-canfd-restart-close-v7-0-accdb11bc845@qq.com

Changes in v7:
- Clarify that running checks do not serialize recovery with close, and
  keep the restart-ms example tied to configuration while down.
- Introduce Rockchip restart/IRQ synchronization and TX protection
  together, keeping close cancellation and open failure cleanup in
  separate patches.
- Build on the CAN skb and Rockchip TX fixes, reusing the TX lock and
  adapting failure cleanup to the updated skb ownership contract.
- Link to v6:
  https://patch.msgid.link/20261017-rockchip-canfd-restart-close-v6-0-ed605feb4b6e@qq.com

Changes in v6:
- Update the can_bus_off() comment and document the running-interface
  requirement for automatic recovery.
- Explain Rockchip's use of the cancellation helper.
- Release the original TX skb after unlocking.
- Abort TX submission if echo preparation fails.
- Link to v5:
  https://patch.msgid.link/20261015-rockchip-canfd-restart-close-v5-0-ae77327037c9@qq.com

Changes in v5:
- Drop consumed RX FIFO entries under tx_lock when TX is disabled
  instead of only skipping echo filtering.
- Link to v4:
  https://patch.msgid.link/20261015-rockchip-canfd-restart-close-v4-0-ad149ff79450@qq.com

Changes in v4:
- Serialize timecounter_cyc2time() with the worker's timecounter_read()
  and startup's timecounter_init() using timestamp_lock.
- Update rkcanfd_skb_set_timestamp() to take a non-const private pointer
  and document the expanded scope of timestamp_lock.
- Link to v3:
  https://patch.msgid.link/20261014-rockchip-canfd-restart-close-v3-0-f0eb41090242@qq.com

Changes in v3:
- Replace disable_irq()/enable_irq() in Rockchip restart with device
  interrupt masking, mask readback, irq_suspended and synchronize_irq().
- Use release/acquire ordering when resuming the IRQ handler.
- Initialize timestamp delayed work once at probe and synchronously
  cancel it before restart reinitializes the timecounter.
- Balance RX offload enablement when request_irq() fails during open.
- Prevent timestamp work from reading the counter or rearming after
  deactivation, with cancellation outside the lock.
- Drain TX submission and RX-side echo users before publishing BUS_OFF,
  protecting the core's pre-restart echo flush.
- Serialize carrier restoration, IRQ enablement and queue wake with a new
  bus-off; suspend shared IRQ handling during open until startup finishes.
- Link to v2:
  https://lore.kernel.org/linux-can/tencent_82C93561D200C84C24608C80049C23EEF80A@qq.com/

Changes in v2:
- Split the series into the common checks, the cancellation helper, and
  its use in Rockchip.
- Check netif_running() after the do_set_mode capability check and before
  the restart notification, echo cleanup, and carrier update.
- Only queue automatic recovery for a running interface; keep reporting
  bus-off and make the log message match the scheduling decision.
- Add close_candev_cancel_restart_sync() in linux/can/dev.h and use it in
  close_candev() without changing the existing cleanup order.
- Replace the Rockchip mutex and closing flag with an early call to the
  helper. Drop the extra close-path IRQ synchronization and mask readback.
- Retain IRQ exclusion around hardware reinitialization in the restart
  callback.
- Link to v1:
  https://lore.kernel.org/linux-can/tencent_5802EE88434010229EDF7A53084D994C6106@qq.com/

To: Marc Kleine-Budde <mkl@pengutronix.de>
To: kernel@pengutronix.de
To: Vincent Mailhol <mailhol@kernel.org>
To: Heiko Stuebner <heiko@sntech.de>
To: Oliver Hartkopp <socketcan@hartkopp.net>
To: "David S. Miller" <davem@davemloft.net>
To: Eric Dumazet <edumazet@kernel.org>
To: Jakub Kicinski <kuba@kernel.org>
To: Paolo Abeni <pabeni@redhat.com>
To: Simon Horman <horms@kernel.org>
To: Jonathan Corbet <corbet@lwn.net>
To: Shuah Khan <skhan@linuxfoundation.org>
To: Randy Dunlap <rdunlap@infradead.org>
To: Wolfgang Grandegger <wg@grandegger.com>
Cc: linux-can@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-rockchip@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-doc@vger.kernel.org

---
Cunhao Lu (10):
      can: rockchip_canfd: prevent TX stall on echo skb failure
      can: rockchip_canfd: serialize TX state and command writes
      can: rockchip_canfd: retry the outstanding TX buffer
      can: dev: check netif_running() before bus-off recovery
      can: dev: add close_candev_cancel_restart_sync()
      can: rockchip_canfd: cancel bus-off restart before closing the device
      can: rockchip_canfd: disable RX offload on open failure
      can: rockchip_canfd: serialize TX with bus-off and restart
      can: rockchip_canfd: prevent timestamp work from rearming after bus-off
      can: rockchip_canfd: serialize timecounter timestamp conversion

 Documentation/networking/can.rst                   | 10 +++-
 drivers/net/can/dev/dev.c                          | 17 ++++--
 drivers/net/can/rockchip/rockchip_canfd-core.c     | 66 ++++++++++++++++++++--
 drivers/net/can/rockchip/rockchip_canfd-rx.c       | 29 +++++++---
 .../net/can/rockchip/rockchip_canfd-timestamp.c    | 43 ++++++++++++--
 drivers/net/can/rockchip/rockchip_canfd-tx.c       | 51 ++++++++++++++---
 drivers/net/can/rockchip/rockchip_canfd.h          | 11 +++-
 include/linux/can/dev.h                            | 17 ++++++
 8 files changed, 209 insertions(+), 35 deletions(-)
---
base-commit: 26e74534310157d284fe9f2518c1503e055b6210
change-id: 20261013-rockchip-canfd-restart-close-ebde5954f1bf

Best regards,
--  
Cunhao Lu <1579567540@qq.com>

[PATCH net v8 01/10] can: rockchip_canfd: prevent TX stall on echo skb failure

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

rkcanfd_start_xmit() advances tx_head and requests transmission even when
can_put_echo_skb() fails. Completion matches self-received frames against
the echo ring, so an entry without an echo skb cannot be completed and
can leave the TX queue stopped.

Install the echo skb before writing the hardware TX buffer. If echo
preparation fails or returns success without installing an echo skb,
drop the frame without writing TX data or commands, advancing tx_head
or adding BQL bytes.

Pass an extra reference to can_put_echo_skb() and retain the original skb
as the frame-data source until submission finishes. This keeps the data
alive even if echo cleanup removes the installed clone. Release the
retained reference on both success and failure.

Backports require can_put_echo_skb() to consume the passed reference on
every return path, including -EINVAL, or equivalent ownership handling.

Fixes: b6661d73290c ("can: rockchip_canfd: add TX PATH")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v8:
- Retain the original skb as the frame-data source and release it after
  submission or failure.
- Reject successful echo preparation if no echo skb was installed.
---
 drivers/net/can/rockchip/rockchip_canfd-tx.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-tx.c b/drivers/net/can/rockchip/rockchip_canfd-tx.c
index 12200dcfd3389..420e59b41059c 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-tx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-tx.c
@@ -117,16 +117,21 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	tx_head = rkcanfd_get_tx_head(priv);
 	reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_head);
 
+	/* Retain the original skb as the frame-data source even if the
+	 * echo skb is removed before submission finishes.
+	 */
+	frame_len = can_skb_get_frame_len(skb);
+	err = can_put_echo_skb(skb_get(skb), ndev, tx_head, frame_len);
+	if (unlikely(err || !priv->can.echo_skb[tx_head]))
+		goto out_drop;
+
 	rkcanfd_write(priv, RKCANFD_REG_FD_TXFRAMEINFO, reg_frameinfo);
 	rkcanfd_write(priv, RKCANFD_REG_FD_TXID, reg_id);
 	for (i = 0; i < cfd->len; i += 4)
 		rkcanfd_write(priv, RKCANFD_REG_FD_TXDATA0 + i,
 			      *(u32 *)(cfd->data + i));
 
-	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);
+	netdev_sent_queue(priv->ndev, frame_len);
 
 	WRITE_ONCE(priv->tx_head, priv->tx_head + 1);
 
@@ -137,6 +142,14 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 				  RKCANFD_TX_STOP_THRESHOLD,
 				  RKCANFD_TX_START_THRESHOLD);
 
+	dev_consume_skb_any(skb);
+
+	return NETDEV_TX_OK;
+
+out_drop:
+	ndev->stats.tx_dropped++;
+	dev_kfree_skb_any(skb);
+
 	return NETDEV_TX_OK;
 }
 

-- 
2.34.1

[PATCH net v8 02/10] can: rockchip_canfd: serialize TX state and command writes

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

rkcanfd_get_effective_tx_free() inspects the tail echo entry while the RX
completion path removes it and advances tx_tail. Concurrent TX submission
can observe inconsistent queue state or dereference an skb already queued
for NAPI, where another CPU can free it. An inconsistent free-space check
can also leave the TX queue stopped without a completion to wake it.

TX submission and RX-side retry also share the MODE/CMD/MODE sequence
used for erratum 12. Interleaving these sequences can restore the default
mode before the other caller writes CMD, bypassing the workaround.

Serialize TX submission with RX completion and retry using tx_lock. Hold
it across the TX space and RX pending checks, echo handling, head/tail
updates, BQL accounting, queue stop/wake and command writes. Require
caller-held locking in the shared helpers and keep TX diagnostics in
the same critical section.

Release the original skb retained by the preceding echo-failure fix after
unlocking and restoring IRQs, so its socket destructor cannot run under
tx_lock. Backports need that retained-reference handling and the CAN skb
ownership fix, or equivalent handling.

This lock covers running TX, completion and retry. Synchronization with
bus-off and controller reinitialization is provided by the later
lifecycle fix.

Fixes: ae002cc32ec4 ("can: rockchip_canfd: prepare to use full TX-FIFO depth")
Fixes: 83f9bd6bf39d ("can: rockchip_canfd: implement workaround for erratum 12")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v8:
- Extend the TX/RX critical sections to cover space and pending checks,
  queue updates and diagnostics; require caller-held helper locking and
  assert it for command writes.
- Release the retained original skb after unlocking.
---
 drivers/net/can/rockchip/rockchip_canfd-core.c |  1 +
 drivers/net/can/rockchip/rockchip_canfd-rx.c   | 23 ++++++++++++++---------
 drivers/net/can/rockchip/rockchip_canfd-tx.c   | 26 +++++++++++++++++++++++---
 drivers/net/can/rockchip/rockchip_canfd.h      |  3 +++
 4 files changed, 41 insertions(+), 12 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index 37c1c22c40c9..1cae86973da5 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -921,6 +921,7 @@ static int rkcanfd_probe(struct platform_device *pdev)
 	priv->can.do_set_mode = rkcanfd_set_mode;
 	priv->can.do_get_berr_counter = rkcanfd_get_berr_counter;
 	priv->ndev = ndev;
+	spin_lock_init(&priv->tx_lock);
 
 	match = device_get_match_data(&pdev->dev);
 	if (match) {
diff --git a/drivers/net/can/rockchip/rockchip_canfd-rx.c b/drivers/net/can/rockchip/rockchip_canfd-rx.c
index 24e87daa1df0..23476a334d6c 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-rx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-rx.c
@@ -91,6 +91,7 @@ rkcanfd_fifo_header_to_cfd_header(const struct rkcanfd_priv *priv,
 	return len + cfd->len;
 }
 
+/* Called with tx_lock held. */
 static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 				const struct canfd_frame *cfd_rx, const u32 ts,
 				bool *tx_done)
@@ -101,6 +102,8 @@ static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 	const struct sk_buff *skb;
 	unsigned int tx_tail;
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	tx_tail = rkcanfd_get_tx_tail(priv);
 	skb = priv->can.echo_skb[tx_tail];
 	if (!skb) {
@@ -201,9 +204,11 @@ rkcanfd_fifo_header_empty(const struct rkcanfd_fifo_header *header)
 static int rkcanfd_handle_rx_int_one(struct rkcanfd_priv *priv)
 {
 	struct net_device_stats *stats = &priv->ndev->stats;
-	struct canfd_frame cfd[1] = { }, *skb_cfd;
 	struct rkcanfd_fifo_header header[1] = { };
+	struct canfd_frame cfd[1] = { }, *skb_cfd;
+	bool tx_done = false;
 	struct sk_buff *skb;
+	unsigned long flags;
 	unsigned int len;
 	int err;
 
@@ -237,15 +242,15 @@ static int rkcanfd_handle_rx_int_one(struct rkcanfd_priv *priv)
 		return 0;
 	}
 
-	if (rkcanfd_get_tx_pending(priv)) {
-		bool tx_done = false;
-
+	spin_lock_irqsave(&priv->tx_lock, flags);
+	err = 0;
+	if (rkcanfd_get_tx_pending(priv))
 		err = rkcanfd_rxstx_filter(priv, cfd, header->ts, &tx_done);
-		if (err)
-			return err;
-		if (tx_done && !(priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK))
-			return 0;
-	}
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+	if (err)
+		return err;
+	if (tx_done && !(priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK))
+		return 0;
 
 	/* Manual handling of CAN Bus Error counters. See
 	 * rkcanfd_get_corrected_berr_counter() for detailed
diff --git a/drivers/net/can/rockchip/rockchip_canfd-tx.c b/drivers/net/can/rockchip/rockchip_canfd-tx.c
index 420e59b41059..caa71cf8e39a 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-tx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-tx.c
@@ -14,6 +14,8 @@ static bool rkcanfd_tx_tail_is_eff(const struct rkcanfd_priv *priv)
 	const struct sk_buff *skb;
 	unsigned int tx_tail;
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	if (!rkcanfd_get_tx_pending(priv))
 		return false;
 
@@ -35,6 +37,8 @@ static bool rkcanfd_tx_tail_is_eff(const struct rkcanfd_priv *priv)
 
 unsigned int rkcanfd_get_effective_tx_free(const struct rkcanfd_priv *priv)
 {
+	lockdep_assert_held(&priv->tx_lock);
+
 	if (priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_6 &&
 	    rkcanfd_tx_tail_is_eff(priv))
 		return 0;
@@ -45,6 +49,8 @@ unsigned int rkcanfd_get_effective_tx_free(const struct rkcanfd_priv *priv)
 static void rkcanfd_start_xmit_write_cmd(const struct rkcanfd_priv *priv,
 					 const u32 reg_cmd)
 {
+	lockdep_assert_held(&priv->tx_lock);
+
 	if (priv->devtype_data.quirks & RKCANFD_QUIRK_RK3568_ERRATUM_12)
 		rkcanfd_write(priv, RKCANFD_REG_MODE, priv->reg_mode_default |
 			      RKCANFD_REG_MODE_SPACE_RX_MODE);
@@ -60,6 +66,8 @@ void rkcanfd_xmit_retry(struct rkcanfd_priv *priv)
 	const unsigned int tx_head = rkcanfd_get_tx_head(priv);
 	const u32 reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_head);
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	rkcanfd_start_xmit_write_cmd(priv, reg_cmd);
 }
 
@@ -69,12 +77,15 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	u32 reg_frameinfo, reg_id, reg_cmd;
 	unsigned int tx_head, frame_len;
 	const struct canfd_frame *cfd;
+	unsigned long flags;
 	int err;
 	u8 i;
 
 	if (can_dev_dropped_skb(ndev, skb))
 		return NETDEV_TX_OK;
 
+	spin_lock_irqsave(&priv->tx_lock, flags);
+
 	if (!netif_subqueue_maybe_stop(priv->ndev, 0,
 				       rkcanfd_get_effective_tx_free(priv),
 				       RKCANFD_TX_STOP_THRESHOLD,
@@ -85,7 +96,7 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 				    priv->tx_head, priv->tx_tail,
 				    rkcanfd_get_tx_pending(priv));
 
-		return NETDEV_TX_BUSY;
+		goto out_busy;
 	}
 
 	cfd = (struct canfd_frame *)skb->data;
@@ -117,8 +128,8 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	tx_head = rkcanfd_get_tx_head(priv);
 	reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_head);
 
-	/* Retain the original skb as the frame-data source even if the
-	 * echo skb is removed before submission finishes.
+	/* Keep the original skb alive until IRQs are restored so echo
+	 * preparation cannot invoke its socket destructor under tx_lock.
 	 */
 	frame_len = can_skb_get_frame_len(skb);
 	err = can_put_echo_skb(skb_get(skb), ndev, tx_head, frame_len);
@@ -142,15 +153,22 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 				  RKCANFD_TX_STOP_THRESHOLD,
 				  RKCANFD_TX_START_THRESHOLD);
 
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
 	dev_consume_skb_any(skb);
 
 	return NETDEV_TX_OK;
 
 out_drop:
 	ndev->stats.tx_dropped++;
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
 	dev_kfree_skb_any(skb);
 
 	return NETDEV_TX_OK;
+
+out_busy:
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+
+	return NETDEV_TX_BUSY;
 }
 
 void rkcanfd_handle_tx_done_one(struct rkcanfd_priv *priv, const u32 ts,
@@ -160,6 +178,8 @@ void rkcanfd_handle_tx_done_one(struct rkcanfd_priv *priv, const u32 ts,
 	unsigned int tx_tail;
 	struct sk_buff *skb;
 
+	lockdep_assert_held(&priv->tx_lock);
+
 	tx_tail = rkcanfd_get_tx_tail(priv);
 	skb = priv->can.echo_skb[tx_tail];
 
diff --git a/drivers/net/can/rockchip/rockchip_canfd.h b/drivers/net/can/rockchip/rockchip_canfd.h
index 95bea9bfd8a2..077dd57d42de 100644
--- a/drivers/net/can/rockchip/rockchip_canfd.h
+++ b/drivers/net/can/rockchip/rockchip_canfd.h
@@ -15,6 +15,7 @@
 #include <linux/netdevice.h>
 #include <linux/reset.h>
 #include <linux/skbuff.h>
+#include <linux/spinlock.h>
 #include <linux/timecounter.h>
 #include <linux/types.h>
 #include <linux/u64_stats_sync.h>
@@ -474,6 +475,8 @@ struct rkcanfd_priv {
 	struct can_rx_offload offload;
 	struct net_device *ndev;
 
+	/* Protect running TX/RX echo state, queue updates and TX commands. */
+	spinlock_t tx_lock;
 	void __iomem *regs;
 	unsigned int tx_head;
 	unsigned int tx_tail;

-- 
2.34.1

[PATCH net v8 03/10] can: rockchip_canfd: retry the outstanding TX buffer

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

rkcanfd_xmit_retry() uses tx_head to select the buffer for the erratum 6
retransmission. With a TX FIFO depth of one, the masked head and tail
indices both select buffer 0. With two buffers and one outstanding frame,
tx_head selects the next free buffer instead of the pending one.

Use tx_tail to retry the outstanding buffer. Otherwise, the pending echo
entry can remain incomplete and leave the TX queue stopped.

Backports must include the preceding TX serialization fix or equivalent
synchronization. It prevents completion and retry from observing a newly
published head before its initial TX command and serializes the
MODE/CMD/MODE sequences used by submission and retry.

Fixes: a5605d61c7dd ("can: rockchip_canfd: enable full TX-FIFO depth of 2")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v8:
- Apply the retry-slot correction after TX serialization.
---
 drivers/net/can/rockchip/rockchip_canfd-tx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-tx.c b/drivers/net/can/rockchip/rockchip_canfd-tx.c
index caa71cf8e39a..8998b7855d15 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-tx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-tx.c
@@ -63,8 +63,8 @@ static void rkcanfd_start_xmit_write_cmd(const struct rkcanfd_priv *priv,
 
 void rkcanfd_xmit_retry(struct rkcanfd_priv *priv)
 {
-	const unsigned int tx_head = rkcanfd_get_tx_head(priv);
-	const u32 reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_head);
+	const unsigned int tx_tail = rkcanfd_get_tx_tail(priv);
+	const u32 reg_cmd = RKCANFD_REG_CMD_TX_REQ(tx_tail);
 
 	lockdep_assert_held(&priv->tx_lock);
 

-- 
2.34.1

[PATCH net v8 04/10] can: dev: check netif_running() before bus-off recovery

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

The networking core clears __LINK_STATE_START before calling ndo_stop(),
but CAN bus-off recovery neither checks this state before queuing work
nor before calling the driver's restart callback. Recovery can therefore
be queued or started after the interface has begun closing, potentially
re-enabling hardware while the driver is tearing it down.

Check netif_running() in can_restart() before flushing echo skbs, sending
the restart notification or enabling the carrier. Keep the existing
unsupported-operation check first. In can_bus_off(), schedule recovery
only when the check observes the interface running, and make the log
message reflect that decision. Keep reporting bus-off and disabling the
carrier.

These checks do not wait for recovery that has already passed the check,
nor serialize the check with work submission. Drivers still need to
cancel restart work before tearing down resources and quiesce its
producers before their final cleanup.

Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v7:
- Clarify the running checks' limits and configure restart-ms while down.

Changes in v6:
- Update the can_bus_off() comment and document the running-interface
  requirement for automatic recovery.

---

Q: Do the running checks serialize recovery with device close?

A: No. With automatic recovery enabled, a worker can pass the check
before close clears the running bit. Drivers such as FlexCAN still
cancel it after hardware teardown, so their restart callback can run
after shutdown. The Rockchip patches in this series wait for an active
restart before teardown and cancel again after draining the IRQ.
Other drivers need separate lifetime fixes; these checks only reject
recovery that observes down.

Q: Can HI3110 queue restart work after close and outlive the device?

A: Yes. With restart-ms nonzero, its IRQ thread can sample running
before close, then queue work after close_candev() returns. The later
free_irq() drains the producer but does not cancel the queued core
work. A quick reopen can execute stale recovery; removal can leave
work referring to a freed can_priv. The driver's private workqueue
does not own this work. A separate fix must quiesce producers before
final cancellation and protect teardown from an active restart. The
running checks narrow this window but cannot protect freed memory.

Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261017-rockchip-canfd-restart-close-v6-0-ed605feb4b6e%40qq.com
---
 Documentation/networking/can.rst | 10 ++++++++--
 drivers/net/can/dev/dev.c        | 13 ++++++++++---
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/Documentation/networking/can.rst b/Documentation/networking/can.rst
index 51bc70748f753..9debef8702d5f 100644
--- a/Documentation/networking/can.rst
+++ b/Documentation/networking/can.rst
@@ -1302,7 +1302,8 @@ More info to the above output:
 	Automatic restart delay time. If set to a non-zero value, a
 	restart of the CAN controller will be triggered automatically
 	in case of a bus-off condition after the specified delay time
-	in milliseconds. By default it's off.
+	in milliseconds. Recovery is skipped if the interface is found
+	to be down. By default it's off.
 
 "bitrate 125000 sample-point 0.875"
 	Shows the real bit-rate in bits/sec and the sample-point in the
@@ -1376,9 +1377,14 @@ before you can start it to avoid error-prone default settings::
 A device may enter the "bus-off" state if too many errors occurred on
 the CAN bus. Then no more messages are received or sent. An automatic
 bus-off recovery can be enabled by setting the "restart-ms" to a
-non-zero value, e.g.::
+non-zero value while the interface is down, e.g.::
 
+    $ ip link set canX down
     $ ip link set canX type can restart-ms 100
+    $ ip link set canX up
+
+Before scheduling or starting recovery, the kernel checks whether the
+interface is running and skips recovery if it is down.
 
 Alternatively, the application may realize the "bus-off" condition
 by monitoring CAN error message frames and do a restart when
diff --git a/drivers/net/can/dev/dev.c b/drivers/net/can/dev/dev.c
index 769745e22a3c7..a893a49a33813 100644
--- a/drivers/net/can/dev/dev.c
+++ b/drivers/net/can/dev/dev.c
@@ -198,6 +198,9 @@ static int can_restart(struct net_device *dev)
 	if (!priv->do_set_mode)
 		return -EOPNOTSUPP;
 
+	if (!netif_running(dev))
+		return -ENETDOWN;
+
 	if (netif_carrier_ok(dev))
 		netdev_err(dev, "Attempt to restart for bus-off recovery, but carrier is OK?\n");
 
@@ -259,13 +262,17 @@ int can_restart_now(struct net_device *dev)
  *
  * This functions should be called when the device goes bus-off to
  * tell the netif layer that no more packets can be sent or received.
- * If enabled, a timer is started to trigger bus-off recovery.
+ * If automatic recovery is enabled, schedule delayed work unless the
+ * running check observes the interface down. Drivers must still synchronize
+ * recovery with device close.
  */
 void can_bus_off(struct net_device *dev)
 {
 	struct can_priv *priv = netdev_priv(dev);
+	bool restart;
 
-	if (priv->restart_ms)
+	restart = priv->restart_ms && netif_running(dev);
+	if (restart)
 		netdev_info(dev, "bus-off, scheduling restart in %d ms\n",
 			    priv->restart_ms);
 	else
@@ -273,7 +280,7 @@ void can_bus_off(struct net_device *dev)
 
 	netif_carrier_off(dev);
 
-	if (priv->restart_ms)
+	if (restart)
 		schedule_delayed_work(&priv->restart_work,
 				      msecs_to_jiffies(priv->restart_ms));
 }

-- 
2.34.1

[PATCH net v8 06/10] can: rockchip_canfd: cancel bus-off restart before closing the device

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

The close path cancels restart_work in close_candev() only after freeing
the IRQ, disabling RX offload and stopping the controller. A concurrent
restart can re-enable the controller and interrupts after IRQ teardown,
or requeue timestamp work that accesses registers after runtime suspend
has disabled the controller clocks.

Call close_candev_cancel_restart_sync() at the start of ndo_stop(), while
the resources needed by a running restart are still available. Keep
close_candev() after IRQ teardown for final cancellation and echo cleanup.

Fixes: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v7:
- Keep close cancellation separate from restart and open error handling.
---
 drivers/net/can/rockchip/rockchip_canfd-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index 1cae86973da5..59a79fe057e6 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -758,6 +758,7 @@ static int rkcanfd_stop(struct net_device *ndev)
 {
 	struct rkcanfd_priv *priv = netdev_priv(ndev);
 
+	close_candev_cancel_restart_sync(ndev);
 	netif_stop_queue(ndev);
 
 	rkcanfd_chip_interrupts_disable(priv);

-- 
2.34.1

[PATCH net v8 07/10] can: rockchip_canfd: disable RX offload on open failure

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

rkcanfd_open() enables RX offload before requesting the IRQ. If
request_irq() fails, the error path leaves the offload enabled. A later
open calls napi_enable() on an already enabled NAPI instance.

Disable RX offload on that error path before stopping the controller and
releasing the runtime PM reference.

Fixes: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v7:
- Split the open error cleanup into a separate patch.

Changes in v3:
- Disable RX offload when request_irq() fails during open.
---
 drivers/net/can/rockchip/rockchip_canfd-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index 59a79fe057e6..d05264605efc 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -747,6 +747,7 @@ static int rkcanfd_open(struct net_device *ndev)
 	return 0;
 
 out_rkcanfd_chip_stop:
+	can_rx_offload_disable(&priv->offload);
 	rkcanfd_chip_stop_sync(priv, CAN_STATE_STOPPED);
 	pm_runtime_put(ndev->dev.parent);
 out_close_candev:

-- 
2.34.1

[PATCH net v8 08/10] can: rockchip_canfd: serialize TX with bus-off and restart

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

The bus-off path can reset the controller while TX submission or RX-side
echo handling is active. CAN restart flushes echo skbs before set_mode(),
so disabling TX in that callback is too late to protect the echo ring.

Use tx_lock and tx_enabled to drain TX and RX-side echo users before
publishing CAN_STATE_BUS_OFF. Return NETDEV_TX_BUSY while TX is disabled
and drop consumed RX entries so self-transmitted frames cannot escape
echo filtering as ordinary RX.

Before restart, mask device interrupts and flush the mask write, suspend
shared IRQ access, and drain active handlers and timestamp work. After
reinitialization, restore carrier, TX, IRQ handling and the queue under
tx_lock, so the old bus-off IRQ cannot leave carrier off and a new bus-off
takes precedence. Keep synchronous waits outside the lock and other
shared IRQ users enabled.

Keep IRQ handling suspended until open completes and TX disabled on
close or failed open. Initialize timestamp work once at probe.

Fixes: ff60bfbaf67f ("can: rockchip_canfd: add driver for Rockchip CAN-FD controller")
Fixes: b6661d73290c ("can: rockchip_canfd: add TX PATH")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>

---
Changes in v8:
- Move skb ownership handling and running TX/RX critical sections to
  the preceding TX patches.

Changes in v7:
- Introduce restart/IRQ synchronization and TX protection together.
- Reuse prerequisite TX locking and adapt to the updated skb ownership.

Changes in v6:
- Defer the original skb's release until after unlocking.
- Abort TX submission if echo preparation fails.

Changes in v5:
- Drop consumed RX FIFO entries when tx_enabled is false under tx_lock,
  rather than skipping only echo filtering and delivering them as RX.

Changes in v3:
- Replace disable_irq()/enable_irq() with device interrupt masking,
  mask readback, an irq_suspended flag and synchronize_irq().
- Pair release/acquire accesses to publish reinitialized state before
  the IRQ handler resumes, without disabling other shared IRQ users.
- Initialize timestamp delayed work once at probe and synchronously
  cancel it before reinitializing the timestamp state during restart.
---
 drivers/net/can/rockchip/rockchip_canfd-core.c     | 63 +++++++++++++++++++---
 drivers/net/can/rockchip/rockchip_canfd-rx.c       | 10 +++-
 .../net/can/rockchip/rockchip_canfd-timestamp.c    |  6 ++-
 drivers/net/can/rockchip/rockchip_canfd-tx.c       |  4 ++
 drivers/net/can/rockchip/rockchip_canfd.h          |  5 +-
 5 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-core.c b/drivers/net/can/rockchip/rockchip_canfd-core.c
index d05264605efc2..536d9bc812afe 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-core.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-core.c
@@ -20,6 +20,7 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/smp.h>
 #include <linux/string.h>
 
 #include "rockchip_canfd.h"
@@ -325,6 +326,35 @@ static void rkcanfd_chip_start(struct rkcanfd_priv *priv)
 		   rkcanfd_read(priv, RKCANFD_REG_MODE));
 }
 
+static void rkcanfd_tx_disable(struct rkcanfd_priv *priv)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->tx_lock, flags);
+	priv->tx_enabled = false;
+	netif_stop_queue(priv->ndev);
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+}
+
+static void rkcanfd_chip_start_finish(struct rkcanfd_priv *priv)
+{
+	unsigned long flags;
+
+	/* Serialize carrier, IRQ enable and queue wake with a new bus-off. */
+	spin_lock_irqsave(&priv->tx_lock, flags);
+	/* A manual restart may have raced with the old bus-off IRQ's
+	 * netif_carrier_off(). That IRQ is now drained; restore carrier
+	 * before resuming IRQ handling so a new bus-off takes precedence.
+	 */
+	netif_carrier_on(priv->ndev);
+	priv->tx_enabled = true;
+	/* Publish the initialized state before resuming IRQ handling. */
+	smp_store_release(&priv->irq_suspended, false);
+	rkcanfd_chip_interrupts_enable(priv);
+	netif_wake_queue(priv->ndev);
+	spin_unlock_irqrestore(&priv->tx_lock, flags);
+}
+
 static void __rkcanfd_chip_stop(struct rkcanfd_priv *priv, const enum can_state state)
 {
 	priv->can.state = state;
@@ -356,9 +386,17 @@ static int rkcanfd_set_mode(struct net_device *ndev,
 
 	switch (mode) {
 	case CAN_MODE_START:
+		rkcanfd_tx_disable(priv);
+		rkcanfd_chip_interrupts_disable(priv);
+		/* Flush the interrupt mask write before suspending the handler. */
+		rkcanfd_read(priv, RKCANFD_REG_INT_MASK);
+		WRITE_ONCE(priv->irq_suspended, true);
+		/* Wait for handlers that already passed the suspended check. */
+		synchronize_irq(ndev->irq);
+		rkcanfd_timestamp_stop_sync(priv);
+
 		rkcanfd_chip_start(priv);
-		rkcanfd_chip_interrupts_enable(priv);
-		netif_wake_queue(ndev);
+		rkcanfd_chip_start_finish(priv);
 		break;
 
 	default:
@@ -592,6 +630,12 @@ static int rkcanfd_handle_state_error_int(struct rkcanfd_priv *priv)
 	 * handles cf == NULL.
 	 */
 	skb = rkcanfd_alloc_can_err_skb(priv, &cf, &timestamp);
+	if (new_state == CAN_STATE_BUS_OFF) {
+		/* Drain TX before publishing BUS_OFF, which permits a manual
+		 * restart to flush echo SKBs before calling our set_mode().
+		 */
+		rkcanfd_tx_disable(priv);
+	}
 	can_change_state(ndev, cf, tx_state, rx_state);
 
 	if (new_state == CAN_STATE_BUS_OFF) {
@@ -666,6 +710,10 @@ static irqreturn_t rkcanfd_irq(int irq, void *dev_id)
 	struct rkcanfd_priv *priv = dev_id;
 	u32 reg_int_unmasked, reg_int;
 
+	/* Pairs with smp_store_release() in rkcanfd_chip_start_finish(). */
+	if (smp_load_acquire(&priv->irq_suspended))
+		return IRQ_NONE;
+
 	reg_int_unmasked = rkcanfd_read(priv, RKCANFD_REG_INT);
 	reg_int = reg_int_unmasked & ~priv->reg_int_mask_default;
 
@@ -733,6 +781,8 @@ static int rkcanfd_open(struct net_device *ndev)
 	if (err)
 		goto out_close_candev;
 
+	/* The shared IRQ handler may run before request_irq() returns. */
+	WRITE_ONCE(priv->irq_suspended, true);
 	rkcanfd_chip_start(priv);
 	can_rx_offload_enable(&priv->offload);
 
@@ -740,13 +790,12 @@ static int rkcanfd_open(struct net_device *ndev)
 	if (err)
 		goto out_rkcanfd_chip_stop;
 
-	rkcanfd_chip_interrupts_enable(priv);
-
-	netif_start_queue(ndev);
+	rkcanfd_chip_start_finish(priv);
 
 	return 0;
 
 out_rkcanfd_chip_stop:
+	rkcanfd_tx_disable(priv);
 	can_rx_offload_disable(&priv->offload);
 	rkcanfd_chip_stop_sync(priv, CAN_STATE_STOPPED);
 	pm_runtime_put(ndev->dev.parent);
@@ -760,7 +809,7 @@ static int rkcanfd_stop(struct net_device *ndev)
 	struct rkcanfd_priv *priv = netdev_priv(ndev);
 
 	close_candev_cancel_restart_sync(ndev);
-	netif_stop_queue(ndev);
+	rkcanfd_tx_disable(priv);
 
 	rkcanfd_chip_interrupts_disable(priv);
 	free_irq(ndev->irq, priv);
@@ -937,6 +986,8 @@ static int rkcanfd_probe(struct platform_device *pdev)
 	if (err)
 		goto out_free_candev;
 
+	rkcanfd_timestamp_work_init(priv);
+
 	err = rkcanfd_register(priv);
 	if (err)
 		goto out_can_rx_offload_del;
diff --git a/drivers/net/can/rockchip/rockchip_canfd-rx.c b/drivers/net/can/rockchip/rockchip_canfd-rx.c
index 23476a334d6c3..fb98dd0da4913 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-rx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-rx.c
@@ -91,7 +91,7 @@ rkcanfd_fifo_header_to_cfd_header(const struct rkcanfd_priv *priv,
 	return len + cfd->len;
 }
 
-/* Called with tx_lock held. */
+/* Called with tx_lock held and TX enabled. */
 static int rkcanfd_rxstx_filter(struct rkcanfd_priv *priv,
 				const struct canfd_frame *cfd_rx, const u32 ts,
 				bool *tx_done)
@@ -242,7 +242,15 @@ static int rkcanfd_handle_rx_int_one(struct rkcanfd_priv *priv)
 		return 0;
 	}
 
+	/* Drop consumed FIFO entries while TX is disabled to avoid delivering
+	 * self-received frames as ordinary RX without echo filtering.
+	 */
 	spin_lock_irqsave(&priv->tx_lock, flags);
+	if (unlikely(!priv->tx_enabled)) {
+		spin_unlock_irqrestore(&priv->tx_lock, flags);
+		return 0;
+	}
+
 	err = 0;
 	if (rkcanfd_get_tx_pending(priv))
 		err = rkcanfd_rxstx_filter(priv, cfd, header->ts, &tx_done);
diff --git a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
index 72774cd2f94b7..ad582afbbd682 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
@@ -37,6 +37,11 @@ static void rkcanfd_timestamp_work(struct work_struct *work)
 	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
 }
 
+void rkcanfd_timestamp_work_init(struct rkcanfd_priv *priv)
+{
+	INIT_DELAYED_WORK(&priv->timestamp, rkcanfd_timestamp_work);
+}
+
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv)
 {
 	const struct can_bittiming *dbt = &priv->can.fd.data_bittiming;
@@ -73,7 +78,6 @@ void rkcanfd_timestamp_init(struct rkcanfd_priv *priv)
 	max_cycles = min(max_cycles, cc->mask);
 	work_delay_ns = clocksource_cyc2ns(max_cycles, cc->mult, cc->shift);
 	priv->work_delay_jiffies = div_u64(work_delay_ns, 3u * NSEC_PER_SEC / HZ);
-	INIT_DELAYED_WORK(&priv->timestamp, rkcanfd_timestamp_work);
 
 	netdev_dbg(priv->ndev, "clock=%lu.%02luMHz bitrate=%lu.%02luMBit/s div=%u rate=%lu.%02luMHz mult=%u shift=%u delay=%lus\n",
 		   priv->can.clock.freq / MEGA,
diff --git a/drivers/net/can/rockchip/rockchip_canfd-tx.c b/drivers/net/can/rockchip/rockchip_canfd-tx.c
index 8998b7855d15d..6f60d4119812f 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-tx.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-tx.c
@@ -85,6 +85,10 @@ netdev_tx_t rkcanfd_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 		return NETDEV_TX_OK;
 
 	spin_lock_irqsave(&priv->tx_lock, flags);
+	if (unlikely(!priv->tx_enabled)) {
+		netif_stop_queue(ndev);
+		goto out_busy;
+	}
 
 	if (!netif_subqueue_maybe_stop(priv->ndev, 0,
 				       rkcanfd_get_effective_tx_free(priv),
diff --git a/drivers/net/can/rockchip/rockchip_canfd.h b/drivers/net/can/rockchip/rockchip_canfd.h
index 077dd57d42de9..3664124a8da25 100644
--- a/drivers/net/can/rockchip/rockchip_canfd.h
+++ b/drivers/net/can/rockchip/rockchip_canfd.h
@@ -475,7 +475,7 @@ struct rkcanfd_priv {
 	struct can_rx_offload offload;
 	struct net_device *ndev;
 
-	/* Protect running TX/RX echo state, queue updates and TX commands. */
+	/* Serialize TX submission/completion with bus-off and restart. */
 	spinlock_t tx_lock;
 	void __iomem *regs;
 	unsigned int tx_head;
@@ -483,6 +483,8 @@ struct rkcanfd_priv {
 
 	u32 reg_mode_default;
 	u32 reg_int_mask_default;
+	bool tx_enabled;
+	bool irq_suspended;
 	struct rkcanfd_devtype_data devtype_data;
 
 	struct cyclecounter cc;
@@ -554,6 +556,7 @@ int rkcanfd_handle_rx_int(struct rkcanfd_priv *priv);
 
 void rkcanfd_skb_set_timestamp(const struct rkcanfd_priv *priv,
 			       struct sk_buff *skb, const u32 timestamp);
+void rkcanfd_timestamp_work_init(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_start(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_stop(struct rkcanfd_priv *priv);

-- 
2.34.1

[PATCH net v8 09/10] can: rockchip_canfd: prevent timestamp work from rearming after bus-off

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

The bus-off IRQ cancels timestamp work asynchronously. If the worker
is already running, it can requeue itself after cancellation and keep
polling while the controller remains bus-off.

Add a dedicated lock and an active flag, initialized once at probe.
Serialize the worker's active check, counter read and self-requeue with
start and stop. Clear the flag under the lock before cancelling work
so no worker can read the counter or rearm after deactivation. Enable
the flag and schedule the initial work under the same lock at start.

Keep both cancellation calls outside the lock so synchronous stop can
wait for the worker to finish.

Fixes: 4e1a18bab124 ("can: rockchip_canfd: add hardware timestamping support")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>
---
 .../net/can/rockchip/rockchip_canfd-timestamp.c    | 34 +++++++++++++++++++---
 drivers/net/can/rockchip/rockchip_canfd.h          |  3 ++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
index ad582afbbd68..1d2a122770dc 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
@@ -30,18 +30,27 @@ static void rkcanfd_timestamp_work(struct work_struct *work)
 {
 	const struct delayed_work *delayed_work = to_delayed_work(work);
 	struct rkcanfd_priv *priv;
+	unsigned long flags;
 
 	priv = container_of(delayed_work, struct rkcanfd_priv, timestamp);
-	timecounter_read(&priv->tc);
-
-	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
+	spin_lock_irqsave(&priv->timestamp_lock, flags);
+	if (priv->timestamp_active) {
+		timecounter_read(&priv->tc);
+
+		/* Serialize requeueing with timestamp deactivation. */
+		schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
+	}
+	spin_unlock_irqrestore(&priv->timestamp_lock, flags);
 }
 
 void rkcanfd_timestamp_work_init(struct rkcanfd_priv *priv)
 {
+	spin_lock_init(&priv->timestamp_lock);
+	priv->timestamp_active = false;
 	INIT_DELAYED_WORK(&priv->timestamp, rkcanfd_timestamp_work);
 }
 
+/* The caller must quiesce IRQs and timestamp work before reconfiguration. */
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv)
 {
 	const struct can_bittiming *dbt = &priv->can.fd.data_bittiming;
@@ -93,17 +102,34 @@ void rkcanfd_timestamp_init(struct rkcanfd_priv *priv)
 
 void rkcanfd_timestamp_start(struct rkcanfd_priv *priv)
 {
-	timecounter_init(&priv->tc, &priv->cc, ktime_get_real_ns());
+	unsigned long flags;
 
+	spin_lock_irqsave(&priv->timestamp_lock, flags);
+	timecounter_init(&priv->tc, &priv->cc, ktime_get_real_ns());
+	priv->timestamp_active = true;
 	schedule_delayed_work(&priv->timestamp, priv->work_delay_jiffies);
+	spin_unlock_irqrestore(&priv->timestamp_lock, flags);
 }
 
 void rkcanfd_timestamp_stop(struct rkcanfd_priv *priv)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->timestamp_lock, flags);
+	priv->timestamp_active = false;
+	spin_unlock_irqrestore(&priv->timestamp_lock, flags);
+
 	cancel_delayed_work(&priv->timestamp);
 }
 
 void rkcanfd_timestamp_stop_sync(struct rkcanfd_priv *priv)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->timestamp_lock, flags);
+	priv->timestamp_active = false;
+	spin_unlock_irqrestore(&priv->timestamp_lock, flags);
+
+	/* The worker needs timestamp_lock to finish. */
 	cancel_delayed_work_sync(&priv->timestamp);
 }
diff --git a/drivers/net/can/rockchip/rockchip_canfd.h b/drivers/net/can/rockchip/rockchip_canfd.h
index 3664124a8da2..078876769a05 100644
--- a/drivers/net/can/rockchip/rockchip_canfd.h
+++ b/drivers/net/can/rockchip/rockchip_canfd.h
@@ -477,6 +477,8 @@ struct rkcanfd_priv {
 
 	/* Serialize TX submission/completion with bus-off and restart. */
 	spinlock_t tx_lock;
+	/* Protects timestamp_active and worker reads/requeueing. */
+	spinlock_t timestamp_lock;
 	void __iomem *regs;
 	unsigned int tx_head;
 	unsigned int tx_tail;
@@ -485,6 +487,7 @@ struct rkcanfd_priv {
 	u32 reg_int_mask_default;
 	bool tx_enabled;
 	bool irq_suspended;
+	bool timestamp_active;
 	struct rkcanfd_devtype_data devtype_data;
 
 	struct cyclecounter cc;

-- 
2.34.1

[PATCH net v8 10/10] can: rockchip_canfd: serialize timecounter timestamp conversion

[Cunhao Lu via B4 Relay]

From: Cunhao Lu <1579567540@qq.com>

The timestamp worker advances the timecounter with timecounter_read()
while RX, TX completion and error-frame paths use timecounter_cyc2time()
to convert hardware timestamps without holding timestamp_lock.

timecounter_read() updates frac, cycle_last and nsec in separate steps.
A concurrent conversion can observe the new cycle_last with the old
nsec and produce an incorrect timestamp.

Hold timestamp_lock across timecounter_cyc2time(), using the same lock
as timecounter_read() and timecounter_init(). Keep the SKB timestamp
assignment outside the critical section.

TX completion nests timestamp_lock inside tx_lock; no timestamp-lock
holder acquires tx_lock.

Fixes: 4e1a18bab124 ("can: rockchip_canfd: add hardware timestamping support")
Cc: stable@vger.kernel.org
Signed-off-by: Cunhao Lu <1579567540@qq.com>
---
 drivers/net/can/rockchip/rockchip_canfd-timestamp.c | 5 ++++-
 drivers/net/can/rockchip/rockchip_canfd.h           | 4 ++--
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
index 1d2a122770dc..e255bb33a20d 100644
--- a/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
+++ b/drivers/net/can/rockchip/rockchip_canfd-timestamp.c
@@ -15,13 +15,16 @@ static u64 rkcanfd_timestamp_read(struct cyclecounter *cc)
 	return rkcanfd_get_timestamp(priv);
 }
 
-void rkcanfd_skb_set_timestamp(const struct rkcanfd_priv *priv,
+void rkcanfd_skb_set_timestamp(struct rkcanfd_priv *priv,
 			       struct sk_buff *skb, const u32 timestamp)
 {
 	struct skb_shared_hwtstamps *hwtstamps = skb_hwtstamps(skb);
+	unsigned long flags;
 	u64 ns;
 
+	spin_lock_irqsave(&priv->timestamp_lock, flags);
 	ns = timecounter_cyc2time(&priv->tc, timestamp);
+	spin_unlock_irqrestore(&priv->timestamp_lock, flags);
 
 	hwtstamps->hwtstamp = ns_to_ktime(ns);
 }
diff --git a/drivers/net/can/rockchip/rockchip_canfd.h b/drivers/net/can/rockchip/rockchip_canfd.h
index 078876769a05..ecb9e2d6aa19 100644
--- a/drivers/net/can/rockchip/rockchip_canfd.h
+++ b/drivers/net/can/rockchip/rockchip_canfd.h
@@ -477,7 +477,7 @@ struct rkcanfd_priv {
 
 	/* Serialize TX submission/completion with bus-off and restart. */
 	spinlock_t tx_lock;
-	/* Protects timestamp_active and worker reads/requeueing. */
+	/* Protects tc, timestamp_active and worker requeueing. */
 	spinlock_t timestamp_lock;
 	void __iomem *regs;
 	unsigned int tx_head;
@@ -557,7 +557,7 @@ void rkcanfd_ethtool_init(struct rkcanfd_priv *priv);
 
 int rkcanfd_handle_rx_int(struct rkcanfd_priv *priv);
 
-void rkcanfd_skb_set_timestamp(const struct rkcanfd_priv *priv,
+void rkcanfd_skb_set_timestamp(struct rkcanfd_priv *priv,
 			       struct sk_buff *skb, const u32 timestamp);
 void rkcanfd_timestamp_work_init(struct rkcanfd_priv *priv);
 void rkcanfd_timestamp_init(struct rkcanfd_priv *priv);

-- 
2.34.1

Re: [PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races

[Jakub Kicinski]

On Sun, 08 Nov 2026 19:33:27 +0800 Cunhao Lu via B4 Relay wrote:
> Subject: [PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races

please use get_maintainer.pl, do not CC netdev on CAN patches directly.

Re: [PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races

[Cunhao Lu]

Hi,

> > Subject: [PATCH net v8 00/10] can: fix Rockchip TX stalls and bus-off restart/close races
>
> please use get_maintainer.pl, do not CC netdev on CAN patches directly.

I used b4 prep --auto-to-cc, which invokes get_maintainer.pl.
The series modifies Documentation/networking/can.rst, which matches
Documentation/networking/ under NETWORKING [GENERAL] and is not
excluded there, so netdev@vger.kernel.org was added automatically.

I will manually remove netdev@vger.kernel.org from Cc for the next
revision.

Best regards,
Cunhao Lu