Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 17daabb5 authored by Alan Brady's avatar Alan Brady Committed by Jeff Kirsher
Browse files

i40e: Simplify i40e_detect_recover_hung_queue logic 



This patch greatly reduces the unneeded complexity in the
i40e_detect_recover_hung_queue code path.  The previous implementation
set a 'hung bit' which would then get cleared while polling.  If the
detection routine was called a second time with the bit already set, we
would issue a software interrupt.  This patch makes it such that if
interrupts are disabled and we have pending TX descriptors, we trigger a
software interrupt since in, the worst case, queues are already clean
and we have an extra interrupt.

Additionally this patch removes the workaround for lost interrupts as
calling napi_reschedule in this context can cause software interrupts to
fire on the wrong CPU.

Change-ID: Iae108582a3ceb6229ed1d22e4ed6e69cf97aad8d
Signed-off-by: default avatarAlan Brady <alan.brady@intel.com>
Tested-by: default avatarAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 373149fc

drivers/net/ethernet/intel/i40e/i40e.h

+0 −4
Original line number Diff line number Diff line
@@ -617,7 +617,6 @@ struct i40e_vsi { 
	u32 tx_busy;

	u64 tx_linearize;

	u64 tx_force_wb;

	u64 tx_lost_interrupt;

	u32 rx_buf_failed;

	u32 rx_page_failed;
@@ -703,9 +702,6 @@ struct i40e_q_vector { 


	u8 num_ringpairs;	/* total number of ring pairs in vector */



#define I40E_Q_VECTOR_HUNG_DETECT 0 /* Bit Index for hung detection logic */

	unsigned long hung_detected; /* Set/Reset for hung_detection logic */



	cpumask_t affinity_mask;

	struct irq_affinity_notify affinity_notify;

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

+0 −1
Original line number Diff line number Diff line
@@ -89,7 +89,6 @@ static const struct i40e_stats i40e_gstrings_misc_stats[] = { 
	I40E_VSI_STAT("rx_unknown_protocol", eth_stats.rx_unknown_protocol),

	I40E_VSI_STAT("tx_linearize", tx_linearize),

	I40E_VSI_STAT("tx_force_wb", tx_force_wb),

	I40E_VSI_STAT("tx_lost_interrupt", tx_lost_interrupt),

	I40E_VSI_STAT("rx_alloc_fail", rx_buf_failed),

	I40E_VSI_STAT("rx_pg_alloc_fail", rx_page_failed),

};

drivers/net/ethernet/intel/i40e/i40e_main.c

+11 −48
Original line number Diff line number Diff line
@@ -737,7 +737,6 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 
	struct i40e_eth_stats *oes;

	struct i40e_eth_stats *es;     /* device's eth stats */

	u32 tx_restart, tx_busy;

	u64 tx_lost_interrupt;

	struct i40e_ring *p;

	u32 rx_page, rx_buf;

	u64 bytes, packets;
@@ -763,7 +762,6 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 
	rx_b = rx_p = 0;

	tx_b = tx_p = 0;

	tx_restart = tx_busy = tx_linearize = tx_force_wb = 0;

	tx_lost_interrupt = 0;

	rx_page = 0;

	rx_buf = 0;

	rcu_read_lock();
@@ -782,7 +780,6 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 
		tx_busy += p->tx_stats.tx_busy;

		tx_linearize += p->tx_stats.tx_linearize;

		tx_force_wb += p->tx_stats.tx_force_wb;

		tx_lost_interrupt += p->tx_stats.tx_lost_interrupt;



		/* Rx queue is part of the same block as Tx queue */

		p = &p[1];
@@ -801,7 +798,6 @@ static void i40e_update_vsi_stats(struct i40e_vsi *vsi) 
	vsi->tx_busy = tx_busy;

	vsi->tx_linearize = tx_linearize;

	vsi->tx_force_wb = tx_force_wb;

	vsi->tx_lost_interrupt = tx_lost_interrupt;

	vsi->rx_page_failed = rx_page;

	vsi->rx_buf_failed = rx_buf;
@@ -4508,16 +4504,15 @@ static int i40e_pf_wait_queues_disabled(struct i40e_pf *pf) 
 * @vsi: Pointer to VSI struct

 *

 * This function checks specified queue for given VSI. Detects hung condition.

 * Sets hung bit since it is two step process. Before next run of service task

 * if napi_poll runs, it reset 'hung' bit for respective q_vector. If not,

 * hung condition remain unchanged and during subsequent run, this function

 * issues SW interrupt to recover from hung condition.

 * We proactively detect hung TX queues by checking if interrupts are disabled

 * but there are pending descriptors.  If it appears hung, attempt to recover

 * by triggering a SW interrupt.

 **/

static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi)

{

	struct i40e_ring *tx_ring = NULL;

	struct i40e_pf	*pf;

	u32 head, val, tx_pending_hw;

	u32 val, tx_pending;

	int i;



	pf = vsi->back;
@@ -4543,47 +4538,15 @@ static void i40e_detect_recover_hung_queue(int q_idx, struct i40e_vsi *vsi) 
	else

		val = rd32(&pf->hw, I40E_PFINT_DYN_CTL0);



	head = i40e_get_head(tx_ring);



	tx_pending_hw = i40e_get_tx_pending(tx_ring, false);



	/* HW is done executing descriptors, updated HEAD write back,

	 * but SW hasn't processed those descriptors. If interrupt is

	 * not generated from this point ON, it could result into

	 * dev_watchdog detecting timeout on those netdev_queue,

	 * hence proactively trigger SW interrupt.

	 */

	if (tx_pending_hw && (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))) {

		/* NAPI Poll didn't run and clear since it was set */

		if (test_and_clear_bit(I40E_Q_VECTOR_HUNG_DETECT,

				       &tx_ring->q_vector->hung_detected)) {

			netdev_info(vsi->netdev, "VSI_seid %d, Hung TX queue %d, tx_pending_hw: %d, NTC:0x%x, HWB: 0x%x, NTU: 0x%x, TAIL: 0x%x\n",

				    vsi->seid, q_idx, tx_pending_hw,

				    tx_ring->next_to_clean, head,

				    tx_ring->next_to_use,

				    readl(tx_ring->tail));

			netdev_info(vsi->netdev, "VSI_seid %d, Issuing force_wb for TX queue %d, Interrupt Reg: 0x%x\n",

				    vsi->seid, q_idx, val);

			i40e_force_wb(vsi, tx_ring->q_vector);

		} else {

			/* First Chance - detected possible hung */

			set_bit(I40E_Q_VECTOR_HUNG_DETECT,

				&tx_ring->q_vector->hung_detected);

		}

	}

	tx_pending = i40e_get_tx_pending(tx_ring);



	/* This is the case where we have interrupts missing,

	 * so the tx_pending in HW will most likely be 0, but we

	 * will have tx_pending in SW since the WB happened but the

	 * interrupt got lost.

	/* Interrupts are disabled and TX pending is non-zero,

	 * trigger the SW interrupt (don't wait). Worst case

	 * there will be one extra interrupt which may result

	 * into not cleaning any queues because queues are cleaned.

	 */

	if ((!tx_pending_hw) && i40e_get_tx_pending(tx_ring, true) &&

	    (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK))) {

		local_bh_disable();

		if (napi_reschedule(&tx_ring->q_vector->napi))

			tx_ring->tx_stats.tx_lost_interrupt++;

		local_bh_enable();

	}

	if (tx_pending && (!(val & I40E_PFINT_DYN_CTLN_INTENA_MASK)))

		i40e_force_wb(vsi, tx_ring->q_vector);

}



/**

drivers/net/ethernet/intel/i40e/i40e_txrx.c

+3 −9
Original line number Diff line number Diff line
@@ -711,19 +711,15 @@ void i40e_free_tx_resources(struct i40e_ring *tx_ring) 
/**

 * i40e_get_tx_pending - how many tx descriptors not processed

 * @tx_ring: the ring of descriptors

 * @in_sw: is tx_pending being checked in SW or HW

 *

 * Since there is no access to the ring head register

 * in XL710, we need to use our local copies

 **/

u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw)

u32 i40e_get_tx_pending(struct i40e_ring *ring)

{

	u32 head, tail;



	if (!in_sw)

	head = i40e_get_head(ring);

	else

		head = ring->next_to_clean;

	tail = readl(ring->tail);



	if (head != tail)
@@ -846,7 +842,7 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi, 
		 * them to be written back in case we stay in NAPI.

		 * In this mode on X722 we do not enable Interrupt.

		 */

		unsigned int j = i40e_get_tx_pending(tx_ring, false);

		unsigned int j = i40e_get_tx_pending(tx_ring);



		if (budget &&

		    ((j / WB_STRIDE) == 0) && (j > 0) &&
@@ -2126,8 +2122,6 @@ int i40e_napi_poll(struct napi_struct *napi, int budget) 
		return 0;

	}



	/* Clear hung_detected bit */

	clear_bit(I40E_Q_VECTOR_HUNG_DETECT, &q_vector->hung_detected);

	/* Since the actual Tx work is minimal, we can give the Tx a larger

	 * budget and be more aggressive about cleaning up the Tx descriptors.

	 */

drivers/net/ethernet/intel/i40e/i40e_txrx.h

+1 −2
Original line number Diff line number Diff line
@@ -275,7 +275,6 @@ struct i40e_tx_queue_stats { 
	u64 tx_done_old;

	u64 tx_linearize;

	u64 tx_force_wb;

	u64 tx_lost_interrupt;

};



struct i40e_rx_queue_stats {
@@ -400,7 +399,7 @@ void i40e_free_tx_resources(struct i40e_ring *tx_ring); 
void i40e_free_rx_resources(struct i40e_ring *rx_ring);

int i40e_napi_poll(struct napi_struct *napi, int budget);

void i40e_force_wb(struct i40e_vsi *vsi, struct i40e_q_vector *q_vector);

u32 i40e_get_tx_pending(struct i40e_ring *ring, bool in_sw);

u32 i40e_get_tx_pending(struct i40e_ring *ring);

int __i40e_maybe_stop_tx(struct i40e_ring *tx_ring, int size);

bool __i40e_chk_linearize(struct sk_buff *skb);