sfc: Fix bugs in RX queue flushing

Avoid overrunning the hardware limit of 4 concurrent RX queue flushes.
Expand the queue flush state to support this.  Make similar changes to
TX flushing to keep the code symmetric.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index 2f1f1fc..e1b9ce3 100644 (file)
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -109,6 +109,9 @@ MODULE_PARM_DESC(rx_xon_thresh_bytes, "RX fifo XON threshold");
 /* Size and alignment of special buffers (4KB) */
 #define FALCON_BUF_SIZE 4096
 
+/* Depth of RX flush request fifo */
+#define FALCON_RX_FLUSH_COUNT 4
+
 #define FALCON_IS_DUAL_FUNC(efx)               \
        (falcon_rev(efx) < FALCON_REV_B0)
 
@@ -426,7 +429,7 @@ void falcon_init_tx(struct efx_tx_queue *tx_queue)
        efx_oword_t tx_desc_ptr;
        struct efx_nic *efx = tx_queue->efx;
 
-       tx_queue->flushed = false;
+       tx_queue->flushed = FLUSH_NONE;
 
        /* Pin TX descriptor ring */
        falcon_init_special_buffer(efx, &tx_queue->txd);
@@ -476,6 +479,8 @@ static void falcon_flush_tx_queue(struct efx_tx_queue *tx_queue)
        struct efx_nic *efx = tx_queue->efx;
        efx_oword_t tx_flush_descq;
 
+       tx_queue->flushed = FLUSH_PENDING;
+
        /* Post a flush command */
        EFX_POPULATE_OWORD_2(tx_flush_descq,
                             FRF_AZ_TX_FLUSH_DESCQ_CMD, 1,
@@ -489,7 +494,7 @@ void falcon_fini_tx(struct efx_tx_queue *tx_queue)
        efx_oword_t tx_desc_ptr;
 
        /* The queue should have been flushed */
-       WARN_ON(!tx_queue->flushed);
+       WARN_ON(tx_queue->flushed != FLUSH_DONE);
 
        /* Remove TX descriptor ring from card */
        EFX_ZERO_OWORD(tx_desc_ptr);
@@ -578,7 +583,7 @@ void falcon_init_rx(struct efx_rx_queue *rx_queue)
                rx_queue->queue, rx_queue->rxd.index,
                rx_queue->rxd.index + rx_queue->rxd.entries - 1);
 
-       rx_queue->flushed = false;
+       rx_queue->flushed = FLUSH_NONE;
 
        /* Pin RX descriptor ring */
        falcon_init_special_buffer(efx, &rx_queue->rxd);
@@ -607,6 +612,8 @@ static void falcon_flush_rx_queue(struct efx_rx_queue *rx_queue)
        struct efx_nic *efx = rx_queue->efx;
        efx_oword_t rx_flush_descq;
 
+       rx_queue->flushed = FLUSH_PENDING;
+
        /* Post a flush command */
        EFX_POPULATE_OWORD_2(rx_flush_descq,
                             FRF_AZ_RX_FLUSH_DESCQ_CMD, 1,
@@ -620,7 +627,7 @@ void falcon_fini_rx(struct efx_rx_queue *rx_queue)
        struct efx_nic *efx = rx_queue->efx;
 
        /* The queue should already have been flushed */
-       WARN_ON(!rx_queue->flushed);
+       WARN_ON(rx_queue->flushed != FLUSH_DONE);
 
        /* Remove RX descriptor ring from card */
        EFX_ZERO_OWORD(rx_desc_ptr);
@@ -1181,7 +1188,7 @@ static void falcon_poll_flush_events(struct efx_nic *efx)
                                                   FSF_AZ_DRIVER_EV_SUBDATA);
                        if (ev_queue < EFX_TX_QUEUE_COUNT) {
                                tx_queue = efx->tx_queue + ev_queue;
-                               tx_queue->flushed = true;
+                               tx_queue->flushed = FLUSH_DONE;
                        }
                } else if (ev_code == FSE_AZ_EV_CODE_DRIVER_EV &&
                           ev_sub_code == FSE_AZ_RX_DESCQ_FLS_DONE_EV) {
@@ -1191,17 +1198,29 @@ static void falcon_poll_flush_events(struct efx_nic *efx)
                                *event, FSF_AZ_DRIVER_EV_RX_FLUSH_FAIL);
                        if (ev_queue < efx->n_rx_queues) {
                                rx_queue = efx->rx_queue + ev_queue;
-
-                               /* retry the rx flush */
-                               if (ev_failed)
-                                       falcon_flush_rx_queue(rx_queue);
-                               else
-                                       rx_queue->flushed = true;
+                               rx_queue->flushed =
+                                       ev_failed ? FLUSH_FAILED : FLUSH_DONE;
                        }
                }
 
+               /* We're about to destroy the queue anyway, so
+                * it's ok to throw away every non-flush event */
+               EFX_SET_QWORD(*event);
+
                read_ptr = (read_ptr + 1) & EFX_EVQ_MASK;
        } while (read_ptr != end_ptr);
+
+       channel->eventq_read_ptr = read_ptr;
+}
+
+static void falcon_prepare_flush(struct efx_nic *efx)
+{
+       falcon_deconfigure_mac_wrapper(efx);
+
+       /* Wait for the tx and rx fifo's to get to the next packet boundary
+        * (~1ms without back-pressure), then to drain the remainder of the
+        * fifo's at data path speeds (negligible), with a healthy margin. */
+       msleep(10);
 }
 
 /* Handle tx and rx flushes at the same time, since they run in
@@ -1211,50 +1230,56 @@ int falcon_flush_queues(struct efx_nic *efx)
 {
        struct efx_rx_queue *rx_queue;
        struct efx_tx_queue *tx_queue;
-       int i;
-       bool outstanding;
+       int i, tx_pending, rx_pending;
 
-       /* Issue flush requests */
-       efx_for_each_tx_queue(tx_queue, efx) {
-               tx_queue->flushed = false;
+       falcon_prepare_flush(efx);
+
+       /* Flush all tx queues in parallel */
+       efx_for_each_tx_queue(tx_queue, efx)
                falcon_flush_tx_queue(tx_queue);
-       }
-       efx_for_each_rx_queue(rx_queue, efx) {
-               rx_queue->flushed = false;
-               falcon_flush_rx_queue(rx_queue);
-       }
 
-       /* Poll the evq looking for flush completions. Since we're not pushing
-        * any more rx or tx descriptors at this point, we're in no danger of
-        * overflowing the evq whilst we wait */
+       /* The hardware supports four concurrent rx flushes, each of which may
+        * need to be retried if there is an outstanding descriptor fetch */
        for (i = 0; i < FALCON_FLUSH_POLL_COUNT; ++i) {
-               msleep(FALCON_FLUSH_INTERVAL);
-               falcon_poll_flush_events(efx);
+               rx_pending = tx_pending = 0;
+               efx_for_each_rx_queue(rx_queue, efx) {
+                       if (rx_queue->flushed == FLUSH_PENDING)
+                               ++rx_pending;
+               }
+               efx_for_each_rx_queue(rx_queue, efx) {
+                       if (rx_pending == FALCON_RX_FLUSH_COUNT)
+                               break;
+                       if (rx_queue->flushed == FLUSH_FAILED ||
+                           rx_queue->flushed == FLUSH_NONE) {
+                               falcon_flush_rx_queue(rx_queue);
+                               ++rx_pending;
+                       }
+               }
+               efx_for_each_tx_queue(tx_queue, efx) {
+                       if (tx_queue->flushed != FLUSH_DONE)
+                               ++tx_pending;
+               }
 
-               /* Check if every queue has been succesfully flushed */
-               outstanding = false;
-               efx_for_each_tx_queue(tx_queue, efx)
-                       outstanding |= !tx_queue->flushed;
-               efx_for_each_rx_queue(rx_queue, efx)
-                       outstanding |= !rx_queue->flushed;
-               if (!outstanding)
+               if (rx_pending == 0 && tx_pending == 0)
                        return 0;
+
+               msleep(FALCON_FLUSH_INTERVAL);
+               falcon_poll_flush_events(efx);
        }
 
        /* Mark the queues as all flushed. We're going to return failure
-        * leading to a reset, or fake up success anyway. "flushed" now
-        * indicates that we tried to flush. */
+        * leading to a reset, or fake up success anyway */
        efx_for_each_tx_queue(tx_queue, efx) {
-               if (!tx_queue->flushed)
+               if (tx_queue->flushed != FLUSH_DONE)
                        EFX_ERR(efx, "tx queue %d flush command timed out\n",
                                tx_queue->queue);
-               tx_queue->flushed = true;
+               tx_queue->flushed = FLUSH_DONE;
        }
        efx_for_each_rx_queue(rx_queue, efx) {
-               if (!rx_queue->flushed)
+               if (rx_queue->flushed != FLUSH_DONE)
                        EFX_ERR(efx, "rx queue %d flush command timed out\n",
                                rx_queue->queue);
-               rx_queue->flushed = true;
+               rx_queue->flushed = FLUSH_DONE;
        }
 
        if (EFX_WORKAROUND_7803(efx))

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index ac808d5..d0755ab 100644 (file)
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -113,6 +113,13 @@ struct efx_special_buffer {
        int entries;
 };
 
+enum efx_flush_state {
+       FLUSH_NONE,
+       FLUSH_PENDING,
+       FLUSH_FAILED,
+       FLUSH_DONE,
+};
+
 /**
  * struct efx_tx_buffer - An Efx TX buffer
  * @skb: The associated socket buffer.
@@ -189,7 +196,7 @@ struct efx_tx_queue {
        struct efx_nic *nic;
        struct efx_tx_buffer *buffer;
        struct efx_special_buffer txd;
-       bool flushed;
+       enum efx_flush_state flushed;
 
        /* Members used mainly on the completion path */
        unsigned int read_count ____cacheline_aligned_in_smp;
@@ -284,7 +291,7 @@ struct efx_rx_queue {
        struct page *buf_page;
        dma_addr_t buf_dma_addr;
        char *buf_data;
-       bool flushed;
+       enum efx_flush_state flushed;
 };
 
 /**