[ 20/72] sfc: Work-around flush timeout when flushes have completed

Greg Kroah-Hartman
2013-03-26T23:24:30Z

From: Daniel Pieczko <dpieczko@solarflare.com>

[ Upstream commit 525d9e824018cd7cc8d8d44832ddcd363abfe6e1 ]

We sometimes hit a "failed to flush" timeout on some TX queues, but the
flushes have completed and the flush completion events seem to go missing.
In this case, we can check the TX_DESC_PTR_TBL register and drain the
queues if the flushes had finished.

[bwh: Minor fixes to coding style]
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/sfc/net_driver.h | 1
drivers/net/ethernet/sfc/nic.c | 56 +++++++++++++++++++++++++++++++---
2 files changed, 53 insertions(+), 4 deletions(-)

--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -194,6 +194,7 @@ struct efx_tx_queue {
/* Members shared between paths and sometimes updated */
unsigned int empty_read_count ____cacheline_aligned_in_smp;
#define EFX_EMPTY_COUNT_VALID 0x80000000
+ atomic_t flush_outstanding;
};

/**
--- a/drivers/net/ethernet/sfc/nic.c
+++ b/drivers/net/ethernet/sfc/nic.c
@@ -73,6 +73,8 @@
_EFX_CHANNEL_MAGIC(_EFX_CHANNEL_MAGIC_TX_DRAIN, \
(_tx_queue)->queue)

+static void efx_magic_event(struct efx_channel *channel, u32 magic);
+
/**************************************************************************
*
* Solarstorm hardware access
@@ -495,6 +497,9 @@ static void efx_flush_tx_queue(struct ef
struct efx_nic *efx = tx_queue->efx;
efx_oword_t tx_flush_descq;

+ WARN_ON(atomic_read(&tx_queue->flush_outstanding));
+ atomic_set(&tx_queue->flush_outstanding, 1);
+
EFX_POPULATE_OWORD_2(tx_flush_descq,
FRF_AZ_TX_FLUSH_DESCQ_CMD, 1,
FRF_AZ_TX_FLUSH_DESCQ, tx_queue->queue);
@@ -670,6 +675,47 @@ static bool efx_flush_wake(struct efx_ni
&& atomic_read(&efx->rxq_flush_pending) > 0));
}

+static bool efx_check_tx_flush_complete(struct efx_nic *efx)
+{
+ bool i = true;
+ efx_oword_t txd_ptr_tbl;
+ struct efx_channel *channel;
+ struct efx_tx_queue *tx_queue;
+
+ efx_for_each_channel(channel, efx) {
+ efx_for_each_channel_tx_queue(tx_queue, channel) {
+ efx_reado_table(efx, &txd_ptr_tbl,
+ FR_BZ_TX_DESC_PTR_TBL, tx_queue->queue);
+ if (EFX_OWORD_FIELD(txd_ptr_tbl,
+ FRF_AZ_TX_DESCQ_FLUSH) ||
+ EFX_OWORD_FIELD(txd_ptr_tbl,
+ FRF_AZ_TX_DESCQ_EN)) {
+ netif_dbg(efx, hw, efx->net_dev,
+ "flush did not complete on TXQ %d\n",
+ tx_queue->queue);
+ i = false;
+ } else if (atomic_cmpxchg(&tx_queue->flush_outstanding,
+ 1, 0)) {
+ /* The flush is complete, but we didn't
+ * receive a flush completion event
+ */
+ netif_dbg(efx, hw, efx->net_dev,
+ "flush complete on TXQ %d, so drain "
+ "the queue\n", tx_queue->queue);
+ /* Don't need to increment drain_pending as it
+ * has already been incremented for the queues
+ * which did not drain
+ */
+ efx_magic_event(channel,
+ EFX_CHANNEL_MAGIC_TX_DRAIN(
+ tx_queue));
+ }
+ }
+ }
+
+ return i;
+}
+
/* Flush all the transmit queues, and continue flushing receive queues until
* they're all flushed. Wait for the DRAIN events to be recieved so that there
* are no more RX and TX events left on any channel. */
@@ -730,7 +776,8 @@ int efx_nic_flush_queues(struct efx_nic
timeout);
}

- if (atomic_read(&efx->drain_pending)) {
+ if (atomic_read(&efx->drain_pending) &&
+ !efx_check_tx_flush_complete(efx)) {
netif_err(efx, hw, efx->net_dev, "failed to flush %d queues "
"(rx %d+%d)\n", atomic_read(&efx->drain_pending),
atomic_read(&efx->rxq_flush_outstanding),
@@ -1017,9 +1064,10 @@ efx_handle_tx_flush_done(struct efx_nic
if (qid < EFX_TXQ_TYPES * efx->n_tx_channels) {
tx_queue = efx_get_tx_queue(efx, qid / EFX_TXQ_TYPES,
qid % EFX_TXQ_TYPES);
-
- efx_magic_event(tx_queue->channel,
- EFX_CHANNEL_MAGIC_TX_DRAIN(tx_queue));
+ if (atomic_cmpxchg(&tx_queue->flush_outstanding, 1, 0)) {
+ efx_magic_event(tx_queue->channel,
+ EFX_CHANNEL_MAGIC_TX_DRAIN(tx_queue));
+ }
}
}