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Commit 810b3ae4 authored by Anjali Singhai Jain's avatar Anjali Singhai Jain Committed by Jeff Kirsher
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i40e/i40evf: Ignore a driver perceived Tx hang if the number of desc pending < 4 



We are seeing situations where the driver sees a hang with less than 4
desc pending, if the driver chooses to ignore it the queue progresses
forward and the stack never experiences a real hang.
With this patch we will log a stat when this situation happens
"tx_sluggish" will increment and we can see some more details
at a higher debug level. Other than that we will ignore this
particular case of Tx hang.

Change-ID: I7d1d1666d990e2b12f4f6bed0d17d22e1b6410d5
Signed-off-by: default avatarAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 30650cc5

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

+1 −0
Original line number Diff line number Diff line
@@ -316,6 +316,7 @@ struct i40e_pf { 
	u32 tx_timeout_count;

	u32 tx_timeout_recovery_level;

	unsigned long tx_timeout_last_recovery;

	u32 tx_sluggish_count;

	u32 hw_csum_rx_error;

	u32 led_status;

	u16 corer_count; /* Core reset count */

drivers/net/ethernet/intel/i40e/i40e_debugfs.c

+3 −0
Original line number Diff line number Diff line
@@ -1356,6 +1356,9 @@ static ssize_t i40e_dbg_command_write(struct file *filp, 
				 "emp reset count: %d\n", pf->empr_count);

			dev_info(&pf->pdev->dev,

				 "pf reset count: %d\n", pf->pfr_count);

			dev_info(&pf->pdev->dev,

				 "pf tx sluggish count: %d\n",

				 pf->tx_sluggish_count);

		} else if (strncmp(&cmd_buf[5], "port", 4) == 0) {

			struct i40e_aqc_query_port_ets_config_resp *bw_data;

			struct i40e_dcbx_config *cfg =

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

+9 −1
Original line number Diff line number Diff line
@@ -607,6 +607,7 @@ static u32 i40e_get_tx_pending(struct i40e_ring *ring) 
static bool i40e_check_tx_hang(struct i40e_ring *tx_ring)

{

	u32 tx_pending = i40e_get_tx_pending(tx_ring);

	struct i40e_pf *pf = tx_ring->vsi->back;

	bool ret = false;



	clear_check_for_tx_hang(tx_ring);
@@ -623,10 +624,17 @@ static bool i40e_check_tx_hang(struct i40e_ring *tx_ring) 
	 * pending but without time to complete it yet.

	 */

	if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) &&

	    tx_pending) {

	    (tx_pending >= I40E_MIN_DESC_PENDING)) {

		/* make sure it is true for two checks in a row */

		ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED,

				       &tx_ring->state);

	} else if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) &&

		   (tx_pending < I40E_MIN_DESC_PENDING) &&

		   (tx_pending > 0)) {

		if (I40E_DEBUG_FLOW & pf->hw.debug_mask)

			dev_info(tx_ring->dev, "HW needs some more descs to do a cacheline flush. tx_pending %d, queue %d",

				 tx_pending, tx_ring->queue_index);

		pf->tx_sluggish_count++;

	} else {

		/* update completed stats and disarm the hang check */

		tx_ring->tx_stats.tx_done_old = tx_ring->stats.packets;

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

+1 −0
Original line number Diff line number Diff line
@@ -121,6 +121,7 @@ enum i40e_dyn_idx_t { 
/* Tx Descriptors needed, worst case */

#define TXD_USE_COUNT(S) DIV_ROUND_UP((S), I40E_MAX_DATA_PER_TXD)

#define DESC_NEEDED (MAX_SKB_FRAGS + 4)

#define I40E_MIN_DESC_PENDING	4



#define I40E_TX_FLAGS_CSUM		(u32)(1)

#define I40E_TX_FLAGS_HW_VLAN		(u32)(1 << 1)

drivers/net/ethernet/intel/i40evf/i40e_txrx.c

+4 −2
Original line number Diff line number Diff line
@@ -163,11 +163,13 @@ static bool i40e_check_tx_hang(struct i40e_ring *tx_ring) 
	 * pending but without time to complete it yet.

	 */

	if ((tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) &&

	    tx_pending) {

	    (tx_pending >= I40E_MIN_DESC_PENDING)) {

		/* make sure it is true for two checks in a row */

		ret = test_and_set_bit(__I40E_HANG_CHECK_ARMED,

				       &tx_ring->state);

	} else {

	} else if (!(tx_ring->tx_stats.tx_done_old == tx_ring->stats.packets) ||

		   !(tx_pending < I40E_MIN_DESC_PENDING) ||

		   !(tx_pending > 0)) {

		/* update completed stats and disarm the hang check */

		tx_ring->tx_stats.tx_done_old = tx_ring->stats.packets;

		clear_bit(__I40E_HANG_CHECK_ARMED, &tx_ring->state);