Commit db88681c authored Mar 24, 2023 by Marc Kleine-Budde

Merge patch series "can: m_can: Optimizations for m_can/tcan part 2"

Markus Schneider-Pargmann <msp@baylibre.com> says:

third version part 2, functionally I had to move from spin_lock to
spin_lock_irqsave because of an interrupt that was calling start_xmit,
see attached stack. This is tested on tcan455x but I don't have the
integrated hardware myself so any testing is appreciated.

The series implements many small and bigger throughput improvements.

Changes in v3:
- Remove parenthesis in error messages
- Use memcpy_and_pad for buffer copy in 'can: m_can: Write transmit
  header and data in one transaction'.
- Replace spin_lock with spin_lock_irqsave. I got a report of a
  interrupt that was calling start_xmit just after the netqueue was
  woken up before the locked region was exited. spin_lock_irqsave should
  fix this. I attached the full stack at the end of the mail if someone
  wants to know.
- Rebased to v6.3-rc1.
- Removed tcan4x5x patches from this series.

Changes in v2: https://lore.kernel.org/all/20230125195059.630377-1-msp@baylibre.com
- Rebased on v6.2-rc5
- Fixed missing/broken accounting for non peripheral m_can devices.

part 1:
v1 - https://lore.kernel.org/lkml/20221116205308.2996556-1-msp@baylibre.com
v2 - https://lore.kernel.org/lkml/20221206115728.1056014-1-msp@baylibre.com

part 2:
v1 - https://lore.kernel.org/lkml/20221221152537.751564-1-msp@baylibre.com
v2 - https://lore.kernel.org/lkml/20230125195059.630377-1-msp@baylibre.com

stack of calling start_xmit within locked region:
	[  308.170171]  dump_backtrace+0x0/0x1a0
	[  308.173841]  show_stack+0x18/0x70
	[  308.177158]  sched_show_task+0x154/0x180
	[  308.181084]  dump_cpu_task+0x44/0x54
	[  308.184664]  rcu_dump_cpu_stacks+0xe8/0x12c
	[  308.188846]  rcu_sched_clock_irq+0x9f4/0xd10
	[  308.193118]  update_process_times+0x9c/0xec
	[  308.197304]  tick_sched_handle+0x34/0x60
	[  308.201231]  tick_sched_timer+0x4c/0xa4
	[  308.205071]  __hrtimer_run_queues+0x138/0x1e0
	[  308.209429]  hrtimer_interrupt+0xe8/0x244
	[  308.213440]  arch_timer_handler_phys+0x38/0x50
	[  308.217890]  handle_percpu_devid_irq+0x84/0x130
	[  308.222422]  handle_domain_irq+0x60/0x90
	[  308.226347]  gic_handle_irq+0x54/0x130
	[  308.230099]  do_interrupt_handler+0x34/0x60
	[  308.234286]  el1_interrupt+0x30/0x80
	[  308.237861]  el1h_64_irq_handler+0x18/0x24
	[  308.241958]  el1h_64_irq+0x78/0x7c
	[  308.245360]  queued_spin_lock_slowpath+0xf4/0x390
	[  308.250067]  m_can_start_tx+0x20/0xb0 [m_can]
	[  308.254431]  m_can_start_xmit+0xd8/0x230 [m_can]
	[  308.259054]  dev_hard_start_xmit+0xd4/0x15c
	[  308.263241]  sch_direct_xmit+0xe8/0x370
	[  308.267080]  __qdisc_run+0x118/0x650
	[  308.270660]  net_tx_action+0x118/0x230
	[  308.274409]  _stext+0x124/0x2a0
	[  308.277549]  __irq_exit_rcu+0xe4/0x100
	[  308.281302]  irq_exit+0x10/0x20
	[  308.284444]  handle_domain_irq+0x64/0x90
	[  308.288367]  gic_handle_irq+0x54/0x130
	[  308.292119]  call_on_irq_stack+0x2c/0x54
	[  308.296043]  do_interrupt_handler+0x54/0x60
	[  308.300228]  el1_interrupt+0x30/0x80
	[  308.303804]  el1h_64_irq_handler+0x18/0x24
	[  308.307901]  el1h_64_irq+0x78/0x7c
	[  308.311303]  __netif_schedule+0x78/0xa0
	[  308.315138]  netif_tx_wake_queue+0x50/0x7c
	[  308.319237]  m_can_isr+0x474/0x1710 [m_can]
	[  308.323425]  irq_thread_fn+0x2c/0x9c
	[  308.327005]  irq_thread+0x178/0x2c0
	[  308.330497]  kthread+0x150/0x160
	[  308.333727]  ret_from_fork+0x10/0x20

Link: https://lore.kernel.org/all/20230315110546.2518305-1-msp@baylibre.com


[mkl: apply patches 1...5 only, adjust message accordingly]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

parents a57915ae 9083e0b0

drivers/net/can/m_can/m_can.c

+19 −18

Original line number	Diff line number	Diff line
		@@ -972,8 +972,8 @@ static int m_can_rx_peripheral(struct net_device *dev, u32 irqstatus)
		/* Don't re-enable interrupts if the driver had a fatal error
		* (e.g., FIFO read failure).
		*/
		if (work_done >= 0)
		m_can_enable_all_interrupts(cdev);
		if (work_done < 0)
		m_can_disable_all_interrupts(cdev);

		return work_done;
		}
		@@ -1083,7 +1083,6 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
		return IRQ_NONE;

		/* ACK all irqs */
		if (ir & IR_ALL_INT)
		m_can_write(cdev, M_CAN_IR, ir);

		if (cdev->ops->clear_interrupts)
		@@ -1096,12 +1095,13 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
		*/
		if ((ir & IR_RF0N) \|\| (ir & IR_ERR_ALL_30X)) {
		cdev->irqstatus = ir;
		if (!cdev->is_peripheral) {
		m_can_disable_all_interrupts(cdev);
		if (!cdev->is_peripheral)
		napi_schedule(&cdev->napi);
		else if (m_can_rx_peripheral(dev, ir) < 0)
		} else if (m_can_rx_peripheral(dev, ir) < 0) {
		goto out_fail;
		}
		}

		if (cdev->version == 30) {
		if (ir & IR_TC) {
		@@ -1262,6 +1262,7 @@ static int m_can_set_bittiming(struct net_device *dev)
		static int m_can_chip_config(struct net_device *dev)
		{
		struct m_can_classdev *cdev = netdev_priv(dev);
		u32 interrupts = IR_ALL_INT;
		u32 cccr, test;
		int err;

		@@ -1271,6 +1272,11 @@ static int m_can_chip_config(struct net_device *dev)
		return err;
		}

		/* Disable unused interrupts */
		interrupts &= ~(IR_ARA \| IR_ELO \| IR_DRX \| IR_TEFF \| IR_TEFW \| IR_TFE \|
		IR_TCF \| IR_HPM \| IR_RF1F \| IR_RF1W \| IR_RF1N \|
		IR_RF0F \| IR_RF0W);

		m_can_config_endisable(cdev, true);

		/* RX Buffer/FIFO Element Size 64 bytes data field */
		@@ -1365,16 +1371,13 @@ static int m_can_chip_config(struct net_device *dev)
		m_can_write(cdev, M_CAN_TEST, test);

		/* Enable interrupts */
		m_can_write(cdev, M_CAN_IR, IR_ALL_INT);
		if (!(cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING))
		if (!(cdev->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) {
		if (cdev->version == 30)
		m_can_write(cdev, M_CAN_IE, IR_ALL_INT &
		~(IR_ERR_LEC_30X));
		else
		m_can_write(cdev, M_CAN_IE, IR_ALL_INT &
		~(IR_ERR_LEC_31X));
		interrupts &= ~(IR_ERR_LEC_30X);
		else
		m_can_write(cdev, M_CAN_IE, IR_ALL_INT);
		interrupts &= ~(IR_ERR_LEC_31X);
		}
		m_can_write(cdev, M_CAN_IE, interrupts);

		/* route all interrupts to INT0 */
		m_can_write(cdev, M_CAN_ILS, ILS_ALL_INT0);
		@@ -1592,10 +1595,8 @@ static int m_can_close(struct net_device *dev)
		cdev->tx_skb = NULL;
		destroy_workqueue(cdev->tx_wq);
		cdev->tx_wq = NULL;
		}

		if (cdev->is_peripheral)
		can_rx_offload_disable(&cdev->offload);
		}

		close_candev(dev);