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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: 1738cd3ed3 ("Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Netanel Belgazal <netanel@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Netanel Belgazal 2017-06-11 15:42:50 +03:00 committed by David S. Miller
parent a2cc5198da
commit 800c55cb76
3 changed files with 50 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/ethernet/amazon/ena/ena_ethtool.c
View File

@ -80,7 +80,6 @@ static const struct ena_stats ena_stats_tx_strings[] = {
ENA_STAT_TX_ENTRY(tx_poll),
ENA_STAT_TX_ENTRY(doorbells),
ENA_STAT_TX_ENTRY(prepare_ctx_err),
ENA_STAT_TX_ENTRY(missing_tx_comp),
ENA_STAT_TX_ENTRY(bad_req_id),
};

66
drivers/net/ethernet/amazon/ena/ena_netdev.c
View File

@ -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->last_jiffies = jiffies;
tx_info->print_once = 0;
tx_ring->next_to_use = ENA_TX_RING_IDX_NEXT(next_to_use,
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");
}
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;
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;
int i, j, budget;
u32 missed_tx;
int i, budget, rc;
/* Make sure the driver doesn't turn the device in other process */
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++) {
tx_ring = &adapter->tx_ring[i];
for (j = 0; j < tx_ring->ring_size; j++) {
tx_buf = &tx_ring->tx_buffer_info[j];
last_jiffies = tx_buf->last_jiffies;
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);
}
}
}
rc = check_missing_comp_in_queue(adapter, tx_ring);
if (unlikely(rc))
return;
budget--;
if (!budget)

14
drivers/net/ethernet/amazon/ena/ena_netdev.h
View File

@ -146,7 +146,18 @@ struct ena_tx_buffer {
u32 tx_descs;
/* num of buffers used by this skb */
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;
struct ena_com_buf bufs[ENA_PKT_MAX_BUFS];
} ____cacheline_aligned;
@ -170,7 +181,6 @@ struct ena_stats_tx {
u64 napi_comp;
u64 tx_poll;
u64 doorbells;
u64 missing_tx_comp;
u64 bad_req_id;
};