sfc: complete the next packet when we receive a timestamp

We now ignore the "completion" event when using tx queue timestamping,
and only pay attention to the two (high and low) timestamp events. The
NIC will send a pair of timestamp events for every packet transmitted.
The current firmware may merge the completion events, and it is possible
that future versions may reorder the completion and timestamp events.
As such the completion event is not useful.

Without this patch in place a merged completion event on a queue with
timestamping will cause a "spurious TX completion" error. This affects
SFN8000-series adapters.

Signed-off-by: Tom Zhao <tzhao@solarflare.com>
Acked-by: Martin Habets <mhabets@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 52113b7529d6fecd3bcbb5332a98a39a358befb4..3f16bd807c6ef65b71917a9a5af5b7235db18b9b 100644 (file)
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -2853,11 +2853,24 @@ efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
        }
 
        /* Transmit timestamps are only available for 8XXX series. They result
-        * in three events per packet. These occur in order, and are:
-        *  - the normal completion event
+        * in up to three events per packet. These occur in order, and are:
+        *  - the normal completion event (may be omitted)
         *  - the low part of the timestamp
         *  - the high part of the timestamp
         *
+        * It's possible for multiple completion events to appear before the
+        * corresponding timestamps. So we can for example get:
+        *  COMP N
+        *  COMP N+1
+        *  TS_LO N
+        *  TS_HI N
+        *  TS_LO N+1
+        *  TS_HI N+1
+        *
+        * In addition it's also possible for the adjacent completions to be
+        * merged, so we may not see COMP N above. As such, the completion
+        * events are not very useful here.
+        *
         * Each part of the timestamp is itself split across two 16 bit
         * fields in the event.
         */
@@ -2865,17 +2878,7 @@ efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
 
        switch (tx_ev_type) {
        case TX_TIMESTAMP_EVENT_TX_EV_COMPLETION:
-               /* In case of Queue flush or FLR, we might have received
-                * the previous TX completion event but not the Timestamp
-                * events.
-                */
-               if (tx_queue->completed_desc_ptr != tx_queue->ptr_mask)
-                       efx_xmit_done(tx_queue, tx_queue->completed_desc_ptr);
-
-               tx_ev_desc_ptr = EFX_QWORD_FIELD(*event,
-                                                ESF_DZ_TX_DESCR_INDX);
-               tx_queue->completed_desc_ptr =
-                                       tx_ev_desc_ptr & tx_queue->ptr_mask;
+               /* Ignore this event - see above. */
                break;
 
        case TX_TIMESTAMP_EVENT_TX_EV_TSTAMP_LO:
@@ -2887,8 +2890,7 @@ efx_ef10_handle_tx_event(struct efx_channel *channel, efx_qword_t *event)
                ts_part = efx_ef10_extract_event_ts(event);
                tx_queue->completed_timestamp_major = ts_part;
 
-               efx_xmit_done(tx_queue, tx_queue->completed_desc_ptr);
-               tx_queue->completed_desc_ptr = tx_queue->ptr_mask;
+               efx_xmit_done_single(tx_queue);
                break;
 
        default:

diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index f1bdb04efbe4d326ebc12f7f1fd544467249825f..95395d67ea2d662878d0dc8cac63b90424db1200 100644 (file)
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -20,6 +20,7 @@ netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb,
                                struct net_device *net_dev);
 netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb);
 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index);
+void efx_xmit_done_single(struct efx_tx_queue *tx_queue);
 int efx_setup_tc(struct net_device *net_dev, enum tc_setup_type type,
                 void *type_data);
 extern unsigned int efx_piobuf_size;

diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 9f9886f222c864d9dfb06bf6c39ce2900c064648..8164f0edcbf0aa13f57cc24420fb8965374d5589 100644 (file)
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -208,8 +208,6 @@ struct efx_tx_buffer {
  *     avoid cache-line ping-pong between the xmit path and the
  *     completion path.
  * @merge_events: Number of TX merged completion events
- * @completed_desc_ptr: Most recent completed pointer - only used with
- *      timestamping.
  * @completed_timestamp_major: Top part of the most recent tx timestamp.
  * @completed_timestamp_minor: Low part of the most recent tx timestamp.
  * @insert_count: Current insert pointer
@@ -269,7 +267,6 @@ struct efx_tx_queue {
        unsigned int merge_events;
        unsigned int bytes_compl;
        unsigned int pkts_compl;
-       unsigned int completed_desc_ptr;
        u32 completed_timestamp_major;
        u32 completed_timestamp_minor;
 

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 04d7f41d7ed90c4107a0093718523d57b2a17aa5..8aafc54a4684469d645e9304733e6f8f49c6a5b3 100644 (file)
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -535,6 +535,44 @@ netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb,
        return efx_enqueue_skb(tx_queue, skb);
 }
 
+void efx_xmit_done_single(struct efx_tx_queue *tx_queue)
+{
+       unsigned int pkts_compl = 0, bytes_compl = 0;
+       unsigned int read_ptr;
+       bool finished = false;
+
+       read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
+
+       while (!finished) {
+               struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
+
+               if (!efx_tx_buffer_in_use(buffer)) {
+                       struct efx_nic *efx = tx_queue->efx;
+
+                       netif_err(efx, hw, efx->net_dev,
+                                 "TX queue %d spurious single TX completion\n",
+                                 tx_queue->queue);
+                       efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
+                       return;
+               }
+
+               /* Need to check the flag before dequeueing. */
+               if (buffer->flags & EFX_TX_BUF_SKB)
+                       finished = true;
+               efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
+
+               ++tx_queue->read_count;
+               read_ptr = tx_queue->read_count & tx_queue->ptr_mask;
+       }
+
+       tx_queue->pkts_compl += pkts_compl;
+       tx_queue->bytes_compl += bytes_compl;
+
+       EFX_WARN_ON_PARANOID(pkts_compl != 1);
+
+       efx_xmit_done_check_empty(tx_queue);
+}
+
 void efx_init_tx_queue_core_txq(struct efx_tx_queue *tx_queue)
 {
        struct efx_nic *efx = tx_queue->efx;

diff --git a/drivers/net/ethernet/sfc/tx_common.c b/drivers/net/ethernet/sfc/tx_common.c
index b1571e9789d02b94f93902dfeff24386fbabc42f..70876df1da69b92b741975ad3095ef4432ef158b 100644 (file)
--- a/drivers/net/ethernet/sfc/tx_common.c
+++ b/drivers/net/ethernet/sfc/tx_common.c
@@ -80,7 +80,6 @@ void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
        tx_queue->xmit_more_available = false;
        tx_queue->timestamping = (efx_ptp_use_mac_tx_timestamps(efx) &&
                                  tx_queue->channel == efx_ptp_channel(efx));
-       tx_queue->completed_desc_ptr = tx_queue->ptr_mask;
        tx_queue->completed_timestamp_major = 0;
        tx_queue->completed_timestamp_minor = 0;
 
@@ -210,10 +209,9 @@ static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
        while (read_ptr != stop_index) {
                struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
 
-               if (!(buffer->flags & EFX_TX_BUF_OPTION) &&
-                   unlikely(buffer->len == 0)) {
+               if (!efx_tx_buffer_in_use(buffer)) {
                        netif_err(efx, tx_err, efx->net_dev,
-                                 "TX queue %d spurious TX completion id %x\n",
+                                 "TX queue %d spurious TX completion id %d\n",
                                  tx_queue->queue, read_ptr);
                        efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
                        return;
@@ -226,6 +224,19 @@ static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
        }
 }
 
+void efx_xmit_done_check_empty(struct efx_tx_queue *tx_queue)
+{
+       if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
+               tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
+               if (tx_queue->read_count == tx_queue->old_write_count) {
+                       /* Ensure that read_count is flushed. */
+                       smp_mb();
+                       tx_queue->empty_read_count =
+                               tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
+               }
+       }
+}
+
 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 {
        unsigned int fill_level, pkts_compl = 0, bytes_compl = 0;
@@ -256,15 +267,7 @@ void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
                        netif_tx_wake_queue(tx_queue->core_txq);
        }
 
-       /* Check whether the hardware queue is now empty */
-       if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) {
-               tx_queue->old_write_count = READ_ONCE(tx_queue->write_count);
-               if (tx_queue->read_count == tx_queue->old_write_count) {
-                       smp_mb();
-                       tx_queue->empty_read_count =
-                               tx_queue->read_count | EFX_EMPTY_COUNT_VALID;
-               }
-       }
+       efx_xmit_done_check_empty(tx_queue);
 }
 
 /* Remove buffers put into a tx_queue for the current packet.

diff --git a/drivers/net/ethernet/sfc/tx_common.h b/drivers/net/ethernet/sfc/tx_common.h
index f92f1fe3a87ff27baed559478a628fadf2c8818c..99cf7ce2f36c9a169f1239c1e9d1ac17334aaa03 100644 (file)
--- a/drivers/net/ethernet/sfc/tx_common.h
+++ b/drivers/net/ethernet/sfc/tx_common.h
@@ -21,6 +21,12 @@ void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
                        unsigned int *pkts_compl,
                        unsigned int *bytes_compl);
 
+static inline bool efx_tx_buffer_in_use(struct efx_tx_buffer *buffer)
+{
+       return buffer->len || (buffer->flags & EFX_TX_BUF_OPTION);
+}
+
+void efx_xmit_done_check_empty(struct efx_tx_queue *tx_queue);
 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index);
 
 void efx_enqueue_unwind(struct efx_tx_queue *tx_queue,