sfc: get rid of custom busy polling code

In linux-4.5, busy polling was implemented in core
NAPI stack, meaning that all custom implementation can
be removed from drivers.

Not only we remove lot's of tricky code, we also remove
one lock operation in fast path.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Edward Cree <ecree@solarflare.com>
Cc: Bert Kenward <bkenward@solarflare.com>
Acked-by: Bert Kenward <bkenward@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 125 deletions

diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 5927c20ba43f..73810d2d630c 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -491,131 +491,6 @@ struct efx_channel {
 	u32 sync_timestamp_minor;
 };
 
-#ifdef CONFIG_NET_RX_BUSY_POLL
-enum efx_channel_busy_poll_state {
-	EFX_CHANNEL_STATE_IDLE = 0,
-	EFX_CHANNEL_STATE_NAPI = BIT(0),
-	EFX_CHANNEL_STATE_NAPI_REQ_BIT = 1,
-	EFX_CHANNEL_STATE_NAPI_REQ = BIT(1),
-	EFX_CHANNEL_STATE_POLL_BIT = 2,
-	EFX_CHANNEL_STATE_POLL = BIT(2),
-	EFX_CHANNEL_STATE_DISABLE_BIT = 3,
-};
-
-static inline void efx_channel_busy_poll_init(struct efx_channel *channel)
-{
-	WRITE_ONCE(channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE);
-}
-
-/* Called from the device poll routine to get ownership of a channel. */
-static inline bool efx_channel_lock_napi(struct efx_channel *channel)
-{
-	unsigned long prev, old = READ_ONCE(channel->busy_poll_state);
-
-	while (1) {
-		switch (old) {
-		case EFX_CHANNEL_STATE_POLL:
-			/* Ensure efx_channel_try_lock_poll() wont starve us */
-			set_bit(EFX_CHANNEL_STATE_NAPI_REQ_BIT,
-				&channel->busy_poll_state);
-			/* fallthrough */
-		case EFX_CHANNEL_STATE_POLL | EFX_CHANNEL_STATE_NAPI_REQ:
-			return false;
-		default:
-			break;
-		}
-		prev = cmpxchg(&channel->busy_poll_state, old,
-			       EFX_CHANNEL_STATE_NAPI);
-		if (unlikely(prev != old)) {
-			/* This is likely to mean we've just entered polling
-			 * state. Go back round to set the REQ bit.
-			 */
-			old = prev;
-			continue;
-		}
-		return true;
-	}
-}
-
-static inline void efx_channel_unlock_napi(struct efx_channel *channel)
-{
-	/* Make sure write has completed from efx_channel_lock_napi() */
-	smp_wmb();
-	WRITE_ONCE(channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE);
-}
-
-/* Called from efx_busy_poll(). */
-static inline bool efx_channel_try_lock_poll(struct efx_channel *channel)
-{
-	return cmpxchg(&channel->busy_poll_state, EFX_CHANNEL_STATE_IDLE,
-			EFX_CHANNEL_STATE_POLL) == EFX_CHANNEL_STATE_IDLE;
-}
-
-static inline void efx_channel_unlock_poll(struct efx_channel *channel)
-{
-	clear_bit_unlock(EFX_CHANNEL_STATE_POLL_BIT, &channel->busy_poll_state);
-}
-
-static inline bool efx_channel_busy_polling(struct efx_channel *channel)
-{
-	return test_bit(EFX_CHANNEL_STATE_POLL_BIT, &channel->busy_poll_state);
-}
-
-static inline void efx_channel_enable(struct efx_channel *channel)
-{
-	clear_bit_unlock(EFX_CHANNEL_STATE_DISABLE_BIT,
-			 &channel->busy_poll_state);
-}
-
-/* Stop further polling or napi access.
- * Returns false if the channel is currently busy polling.
- */
-static inline bool efx_channel_disable(struct efx_channel *channel)
-{
-	set_bit(EFX_CHANNEL_STATE_DISABLE_BIT, &channel->busy_poll_state);
-	/* Implicit barrier in efx_channel_busy_polling() */
-	return !efx_channel_busy_polling(channel);
-}
-
-#else /* CONFIG_NET_RX_BUSY_POLL */
-
-static inline void efx_channel_busy_poll_init(struct efx_channel *channel)
-{
-}
-
-static inline bool efx_channel_lock_napi(struct efx_channel *channel)
-{
-	return true;
-}
-
-static inline void efx_channel_unlock_napi(struct efx_channel *channel)
-{
-}
-
-static inline bool efx_channel_try_lock_poll(struct efx_channel *channel)
-{
-	return false;
-}
-
-static inline void efx_channel_unlock_poll(struct efx_channel *channel)
-{
-}
-
-static inline bool efx_channel_busy_polling(struct efx_channel *channel)
-{
-	return false;
-}
-
-static inline void efx_channel_enable(struct efx_channel *channel)
-{
-}
-
-static inline bool efx_channel_disable(struct efx_channel *channel)
-{
-	return true;
-}
-#endif /* CONFIG_NET_RX_BUSY_POLL */
-
 /**
  * struct efx_msi_context - Context for each MSI
  * @efx: The associated NIC