sfc: Remove efx_rx_queue::add_lock

Ensure that efx_fast_push_rx_descriptors() must only run
from efx_process_channel() [NAPI], or when napi_disable()
has been executed.

Reimplement the slow fill by sending an event to the
channel, so that NAPI runs, and hanging the subsequent
fast fill off the event handler. Replace the sfc_refill
workqueue and delayed work items with a timer. We do
not need to stop this timer in efx_flush_all() because
it's safe to send the event always; receiving it will
be delayed until NAPI is restarted.

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

1 files changed, 39 insertions, 10 deletions

diff --git a/drivers/net/sfc/nic.c b/drivers/net/sfc/nic.c
index ca9cf1a33803..0ee6fd367e6f 100644
--- a/drivers/net/sfc/nic.c
+++ b/drivers/net/sfc/nic.c
@@ -79,10 +79,14 @@ MODULE_PARM_DESC(rx_xon_thresh_bytes, "RX fifo XON threshold");
 /* Depth of RX flush request fifo */
 #define EFX_RX_FLUSH_COUNT 4
 
-/* Magic value for efx_generate_test_event() */
-#define EFX_CHANNEL_MAGIC(_channel)			\
+/* Generated event code for efx_generate_test_event() */
+#define EFX_CHANNEL_MAGIC_TEST(_channel)	\
 	(0x00010100 + (_channel)->channel)
 
+/* Generated event code for efx_generate_fill_event() */
+#define EFX_CHANNEL_MAGIC_FILL(_channel)	\
+	(0x00010200 + (_channel)->channel)
+
 /**************************************************************************
  *
  * Solarstorm hardware access
@@ -854,6 +858,26 @@ efx_handle_rx_event(struct efx_channel *channel, const efx_qword_t *event)
 		      checksummed, discard);
 }
 
+static void
+efx_handle_generated_event(struct efx_channel *channel, efx_qword_t *event)
+{
+	struct efx_nic *efx = channel->efx;
+	unsigned code;
+
+	code = EFX_QWORD_FIELD(*event, FSF_AZ_DRV_GEN_EV_MAGIC);
+	if (code == EFX_CHANNEL_MAGIC_TEST(channel))
+		++channel->magic_count;
+	else if (code == EFX_CHANNEL_MAGIC_FILL(channel))
+		/* The queue must be empty, so we won't receive any rx
+		 * events, so efx_process_channel() won't refill the
+		 * queue. Refill it here */
+		efx_fast_push_rx_descriptors(&efx->rx_queue[channel->channel]);
+	else
+		EFX_LOG(efx, "channel %d received generated "
+			"event "EFX_QWORD_FMT"\n", channel->channel,
+			EFX_QWORD_VAL(*event));
+}
+
 /* Global events are basically PHY events */
 static void
 efx_handle_global_event(struct efx_channel *channel, efx_qword_t *event)
@@ -997,13 +1021,7 @@ int efx_nic_process_eventq(struct efx_channel *channel, int budget)
 			}
 			break;
 		case FSE_AZ_EV_CODE_DRV_GEN_EV:
-			if (EFX_QWORD_FIELD(event, FSF_AZ_DRV_GEN_EV_MAGIC)
-			    == EFX_CHANNEL_MAGIC(channel))
-				++channel->magic_count;
-
-			EFX_LOG(channel->efx, "channel %d received generated "
-				"event "EFX_QWORD_FMT"\n", channel->channel,
-				EFX_QWORD_VAL(event));
+			efx_handle_generated_event(channel, &event);
 			break;
 		case FSE_AZ_EV_CODE_GLOBAL_EV:
 			efx_handle_global_event(channel, &event);
@@ -1096,7 +1114,18 @@ void efx_nic_remove_eventq(struct efx_channel *channel)
 
 void efx_nic_generate_test_event(struct efx_channel *channel)
 {
-	unsigned int magic = EFX_CHANNEL_MAGIC(channel);
+	unsigned int magic = EFX_CHANNEL_MAGIC_TEST(channel);
+	efx_qword_t test_event;
+
+	EFX_POPULATE_QWORD_2(test_event, FSF_AZ_EV_CODE,
+			     FSE_AZ_EV_CODE_DRV_GEN_EV,
+			     FSF_AZ_DRV_GEN_EV_MAGIC, magic);
+	efx_generate_event(channel, &test_event);
+}
+
+void efx_nic_generate_fill_event(struct efx_channel *channel)
+{
+	unsigned int magic = EFX_CHANNEL_MAGIC_FILL(channel);
 	efx_qword_t test_event;
 
 	EFX_POPULATE_QWORD_2(test_event, FSF_AZ_EV_CODE,