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Commit 800c55cb authored by Netanel Belgazal's avatar Netanel Belgazal Committed by David S. Miller
Browse files

net: ena: bug fix in lost tx packets detection mechanism 



check_for_missing_tx_completions() is called from a timer
task and looking for lost tx packets.
The old implementation accumulate all the lost tx packets
and did not check if those packets were retrieved on a later stage.
This cause to a situation where the driver reset
the device for no reason.

Fixes: 1738cd3e ("Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: default avatarNetanel Belgazal <netanel@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a2cc5198

drivers/net/ethernet/amazon/ena/ena_ethtool.c

+0 −1
Original line number Original line Diff line number Diff line
@@ -80,7 +80,6 @@ static const struct ena_stats ena_stats_tx_strings[] = { 
	ENA_STAT_TX_ENTRY(tx_poll),

	ENA_STAT_TX_ENTRY(tx_poll),

	ENA_STAT_TX_ENTRY(doorbells),

	ENA_STAT_TX_ENTRY(doorbells),

	ENA_STAT_TX_ENTRY(prepare_ctx_err),

	ENA_STAT_TX_ENTRY(prepare_ctx_err),

	ENA_STAT_TX_ENTRY(missing_tx_comp),

	ENA_STAT_TX_ENTRY(bad_req_id),

	ENA_STAT_TX_ENTRY(bad_req_id),

};

};

drivers/net/ethernet/amazon/ena/ena_netdev.c

+38 −28
Original line number Original line Diff line number Diff line
@@ -1995,6 +1995,7 @@ static netdev_tx_t ena_start_xmit(struct sk_buff *skb, struct net_device *dev) 




	tx_info->tx_descs = nb_hw_desc;

	tx_info->tx_descs = nb_hw_desc;

	tx_info->last_jiffies = jiffies;

	tx_info->last_jiffies = jiffies;

	tx_info->print_once = 0;





	tx_ring->next_to_use = ENA_TX_RING_IDX_NEXT(next_to_use,

	tx_ring->next_to_use = ENA_TX_RING_IDX_NEXT(next_to_use,

		tx_ring->ring_size);

		tx_ring->ring_size);
@@ -2564,13 +2565,44 @@ static void ena_fw_reset_device(struct work_struct *work) 
		"Reset attempt failed. Can not reset the device\n");

		"Reset attempt failed. Can not reset the device\n");

}

}





static void check_for_missing_tx_completions(struct ena_adapter *adapter)

static int check_missing_comp_in_queue(struct ena_adapter *adapter,

				       struct ena_ring *tx_ring)

{

{

	struct ena_tx_buffer *tx_buf;

	struct ena_tx_buffer *tx_buf;

	unsigned long last_jiffies;

	unsigned long last_jiffies;

	u32 missed_tx = 0;

	int i;



	for (i = 0; i < tx_ring->ring_size; i++) {

		tx_buf = &tx_ring->tx_buffer_info[i];

		last_jiffies = tx_buf->last_jiffies;

		if (unlikely(last_jiffies &&

			     time_is_before_jiffies(last_jiffies + TX_TIMEOUT))) {

			if (!tx_buf->print_once)

				netif_notice(adapter, tx_err, adapter->netdev,

					     "Found a Tx that wasn't completed on time, qid %d, index %d.\n",

					     tx_ring->qid, i);



			tx_buf->print_once = 1;

			missed_tx++;



			if (unlikely(missed_tx > MAX_NUM_OF_TIMEOUTED_PACKETS)) {

				netif_err(adapter, tx_err, adapter->netdev,

					  "The number of lost tx completions is above the threshold (%d > %d). Reset the device\n",

					  missed_tx, MAX_NUM_OF_TIMEOUTED_PACKETS);

				set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);

				return -EIO;

			}

		}

	}



	return 0;

}



static void check_for_missing_tx_completions(struct ena_adapter *adapter)

{

	struct ena_ring *tx_ring;

	struct ena_ring *tx_ring;

	int i, j, budget;

	int i, budget, rc;

	u32 missed_tx;





	/* Make sure the driver doesn't turn the device in other process */

	/* Make sure the driver doesn't turn the device in other process */

	smp_rmb();

	smp_rmb();
@@ -2586,31 +2618,9 @@ static void check_for_missing_tx_completions(struct ena_adapter *adapter) 
	for (i = adapter->last_monitored_tx_qid; i < adapter->num_queues; i++) {

	for (i = adapter->last_monitored_tx_qid; i < adapter->num_queues; i++) {

		tx_ring = &adapter->tx_ring[i];

		tx_ring = &adapter->tx_ring[i];





		for (j = 0; j < tx_ring->ring_size; j++) {

		rc = check_missing_comp_in_queue(adapter, tx_ring);

			tx_buf = &tx_ring->tx_buffer_info[j];

		if (unlikely(rc))

			last_jiffies = tx_buf->last_jiffies;

			return;

			if (unlikely(last_jiffies && time_is_before_jiffies(last_jiffies + TX_TIMEOUT))) {

				netif_notice(adapter, tx_err, adapter->netdev,

					     "Found a Tx that wasn't completed on time, qid %d, index %d.\n",

					     tx_ring->qid, j);



				u64_stats_update_begin(&tx_ring->syncp);

				missed_tx = tx_ring->tx_stats.missing_tx_comp++;

				u64_stats_update_end(&tx_ring->syncp);



				/* Clear last jiffies so the lost buffer won't

				 * be counted twice.

				 */

				tx_buf->last_jiffies = 0;



				if (unlikely(missed_tx > MAX_NUM_OF_TIMEOUTED_PACKETS)) {

					netif_err(adapter, tx_err, adapter->netdev,

						  "The number of lost tx completion is above the threshold (%d > %d). Reset the device\n",

						  missed_tx, MAX_NUM_OF_TIMEOUTED_PACKETS);

					set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);

				}

			}

		}





		budget--;

		budget--;

		if (!budget)

		if (!budget)

drivers/net/ethernet/amazon/ena/ena_netdev.h

+12 −2
Original line number Original line Diff line number Diff line
@@ -146,7 +146,18 @@ struct ena_tx_buffer { 
	u32 tx_descs;

	u32 tx_descs;

	/* num of buffers used by this skb */

	/* num of buffers used by this skb */

	u32 num_of_bufs;

	u32 num_of_bufs;

	/* Save the last jiffies to detect missing tx packets */



	/* Used for detect missing tx packets to limit the number of prints */

	u32 print_once;

	/* Save the last jiffies to detect missing tx packets

	 *

	 * sets to non zero value on ena_start_xmit and set to zero on

	 * napi and timer_Service_routine.

	 *

	 * while this value is not protected by lock,

	 * a given packet is not expected to be handled by ena_start_xmit

	 * and by napi/timer_service at the same time.

	 */

	unsigned long last_jiffies;

	unsigned long last_jiffies;

	struct ena_com_buf bufs[ENA_PKT_MAX_BUFS];

	struct ena_com_buf bufs[ENA_PKT_MAX_BUFS];

} ____cacheline_aligned;

} ____cacheline_aligned;
@@ -170,7 +181,6 @@ struct ena_stats_tx { 
	u64 napi_comp;

	u64 napi_comp;

	u64 tx_poll;

	u64 tx_poll;

	u64 doorbells;

	u64 doorbells;

	u64 missing_tx_comp;

	u64 bad_req_id;

	u64 bad_req_id;

};

};