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, 3 insertions, 7 deletions

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index ee0ea01c847e..45398039dee6 100644
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -18,6 +18,7 @@
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/if_vlan.h>
+#include <linux/timer.h>
 #include <linux/mdio.h>
 #include <linux/list.h>
 #include <linux/pci.h>
@@ -242,10 +243,6 @@ struct efx_rx_buffer {
  * @added_count: Number of buffers added to the receive queue.
  * @notified_count: Number of buffers given to NIC (<= @added_count).
  * @removed_count: Number of buffers removed from the receive queue.
- * @add_lock: Receive queue descriptor add spin lock.
- *      This lock must be held in order to add buffers to the RX
- *      descriptor ring (rxd and buffer) and to update added_count (but
- *      not removed_count).
  * @max_fill: RX descriptor maximum fill level (<= ring size)
  * @fast_fill_trigger: RX descriptor fill level that will trigger a fast fill
  *      (<= @max_fill)
@@ -259,7 +256,7 @@ struct efx_rx_buffer {
  *      overflow was observed.  It should never be set.
  * @alloc_page_count: RX allocation strategy counter.
  * @alloc_skb_count: RX allocation strategy counter.
- * @work: Descriptor push work thread
+ * @slow_fill: Timer used to defer efx_nic_generate_fill_event().
  * @buf_page: Page for next RX buffer.
  *      We can use a single page for multiple RX buffers. This tracks
  *      the remaining space in the allocation.
@@ -277,7 +274,6 @@ struct efx_rx_queue {
         int added_count;
         int notified_count;
         int removed_count;
-        spinlock_t add_lock;
         unsigned int max_fill;
         unsigned int fast_fill_trigger;
         unsigned int fast_fill_limit;
@@ -285,7 +281,7 @@ struct efx_rx_queue {
         unsigned int min_overfill;
         unsigned int alloc_page_count;
         unsigned int alloc_skb_count;
-        struct delayed_work work;
+        struct timer_list slow_fill;
         unsigned int slow_fill_count;
 
         struct page *buf_page;