Merge branch 'sfc-filter-locking'

Edward Cree says:

====================
sfc: rework locking around filter management

The use of a spinlock to protect filter state combined with the need for a
 sleeping operation (MCDI) to apply that state to the NIC (on EF10) led to
 unfixable race conditions, around the handling of filter restoration after
 an MC reboot.
So, this patch series removes the requirement to be able to modify the SW
 filter table from atomic context, by using a workqueue to request
 asynchronous filter operations (which are needed for ARFS).  Then, the
 filter table locks are changed to mutexes, replacing the dance of spinlocks
 and 'busy' flags.  Also, a mutex is added to protect the RSS context state,
 since otherwise a similar race is possible around restoring that after an
 MC reboot.  While we're at it, fix a couple of other related bugs.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 38 insertions, 42 deletions

diff --git a/drivers/net/ethernet/sfc/farch.c b/drivers/net/ethernet/sfc/farch.c
index ad001e77d554..4a19c7efdf8d 100644
--- a/drivers/net/ethernet/sfc/farch.c
+++ b/drivers/net/ethernet/sfc/farch.c
@@ -1878,6 +1878,7 @@ struct efx_farch_filter_table {
 };
 
 struct efx_farch_filter_state {
+	struct rw_semaphore lock; /* Protects table contents */
 	struct efx_farch_filter_table table[EFX_FARCH_FILTER_TABLE_COUNT];
 };
 
@@ -2397,9 +2398,13 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 	if (rc)
 		return rc;
 
+	down_write(&state->lock);
+
 	table = &state->table[efx_farch_filter_spec_table_id(&spec)];
-	if (table->size == 0)
-		return -EINVAL;
+	if (table->size == 0) {
+		rc = -EINVAL;
+		goto out_unlock;
+	}
 
 	netif_vdbg(efx, hw, efx->net_dev,
 		   "%s: type %d search_limit=%d", __func__, spec.type,
@@ -2412,8 +2417,6 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 			     EFX_FARCH_FILTER_MC_DEF - EFX_FARCH_FILTER_UC_DEF);
 		rep_index = spec.type - EFX_FARCH_FILTER_UC_DEF;
 		ins_index = rep_index;
-
-		spin_lock_bh(&efx->filter_lock);
 	} else {
 		/* Search concurrently for
 		 * (1) a filter to be replaced (rep_index): any filter
@@ -2443,8 +2446,6 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 		ins_index = -1;
 		depth = 1;
 
-		spin_lock_bh(&efx->filter_lock);
-
 		for (;;) {
 			if (!test_bit(i, table->used_bitmap)) {
 				if (ins_index < 0)
@@ -2463,7 +2464,7 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 				/* Case (b) */
 				if (ins_index < 0) {
 					rc = -EBUSY;
-					goto out;
+					goto out_unlock;
 				}
 				rep_index = -1;
 				break;
@@ -2483,11 +2484,11 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 
 		if (spec.priority == saved_spec->priority && !replace_equal) {
 			rc = -EEXIST;
-			goto out;
+			goto out_unlock;
 		}
 		if (spec.priority < saved_spec->priority) {
 			rc = -EPERM;
-			goto out;
+			goto out_unlock;
 		}
 		if (saved_spec->priority == EFX_FILTER_PRI_AUTO ||
 		    saved_spec->flags & EFX_FILTER_FLAG_RX_OVER_AUTO)
@@ -2528,8 +2529,8 @@ s32 efx_farch_filter_insert(struct efx_nic *efx,
 		   __func__, spec.type, ins_index, spec.dmaq_id);
 	rc = efx_farch_filter_make_id(&spec, ins_index);
 
-out:
-	spin_unlock_bh(&efx->filter_lock);
+out_unlock:
+	up_write(&state->lock);
 	return rc;
 }
 
@@ -2604,11 +2605,11 @@ int efx_farch_filter_remove_safe(struct efx_nic *efx,
 	filter_idx = efx_farch_filter_id_index(filter_id);
 	if (filter_idx >= table->size)
 		return -ENOENT;
+	down_write(&state->lock);
 	spec = &table->spec[filter_idx];
 
-	spin_lock_bh(&efx->filter_lock);
 	rc = efx_farch_filter_remove(efx, table, filter_idx, priority);
-	spin_unlock_bh(&efx->filter_lock);
+	up_write(&state->lock);
 
 	return rc;
 }
@@ -2622,30 +2623,28 @@ int efx_farch_filter_get_safe(struct efx_nic *efx,
 	struct efx_farch_filter_table *table;
 	struct efx_farch_filter_spec *spec;
 	unsigned int filter_idx;
-	int rc;
+	int rc = -ENOENT;
+
+	down_read(&state->lock);
 
 	table_id = efx_farch_filter_id_table_id(filter_id);
 	if ((unsigned int)table_id >= EFX_FARCH_FILTER_TABLE_COUNT)
-		return -ENOENT;
+		goto out_unlock;
 	table = &state->table[table_id];
 
 	filter_idx = efx_farch_filter_id_index(filter_id);
 	if (filter_idx >= table->size)
-		return -ENOENT;
+		goto out_unlock;
 	spec = &table->spec[filter_idx];
 
-	spin_lock_bh(&efx->filter_lock);
-
 	if (test_bit(filter_idx, table->used_bitmap) &&
 	    spec->priority == priority) {
 		efx_farch_filter_to_gen_spec(spec_buf, spec);
 		rc = 0;
-	} else {
-		rc = -ENOENT;
 	}
 
-	spin_unlock_bh(&efx->filter_lock);
-
+out_unlock:
+	up_read(&state->lock);
 	return rc;
 }
 
@@ -2658,13 +2657,13 @@ efx_farch_filter_table_clear(struct efx_nic *efx,
 	struct efx_farch_filter_table *table = &state->table[table_id];
 	unsigned int filter_idx;
 
-	spin_lock_bh(&efx->filter_lock);
+	down_write(&state->lock);
 	for (filter_idx = 0; filter_idx < table->size; ++filter_idx) {
 		if (table->spec[filter_idx].priority != EFX_FILTER_PRI_AUTO)
 			efx_farch_filter_remove(efx, table,
 						filter_idx, priority);
 	}
-	spin_unlock_bh(&efx->filter_lock);
+	up_write(&state->lock);
 }
 
 int efx_farch_filter_clear_rx(struct efx_nic *efx,
@@ -2688,7 +2687,7 @@ u32 efx_farch_filter_count_rx_used(struct efx_nic *efx,
 	unsigned int filter_idx;
 	u32 count = 0;
 
-	spin_lock_bh(&efx->filter_lock);
+	down_read(&state->lock);
 
 	for (table_id = EFX_FARCH_FILTER_TABLE_RX_IP;
 	     table_id <= EFX_FARCH_FILTER_TABLE_RX_DEF;
@@ -2701,7 +2700,7 @@ u32 efx_farch_filter_count_rx_used(struct efx_nic *efx,
 		}
 	}
 
-	spin_unlock_bh(&efx->filter_lock);
+	up_read(&state->lock);
 
 	return count;
 }
@@ -2716,7 +2715,7 @@ s32 efx_farch_filter_get_rx_ids(struct efx_nic *efx,
 	unsigned int filter_idx;
 	s32 count = 0;
 
-	spin_lock_bh(&efx->filter_lock);
+	down_read(&state->lock);
 
 	for (table_id = EFX_FARCH_FILTER_TABLE_RX_IP;
 	     table_id <= EFX_FARCH_FILTER_TABLE_RX_DEF;
@@ -2735,7 +2734,7 @@ s32 efx_farch_filter_get_rx_ids(struct efx_nic *efx,
 		}
 	}
 out:
-	spin_unlock_bh(&efx->filter_lock);
+	up_read(&state->lock);
 
 	return count;
 }
@@ -2749,7 +2748,7 @@ void efx_farch_filter_table_restore(struct efx_nic *efx)
 	efx_oword_t filter;
 	unsigned int filter_idx;
 
-	spin_lock_bh(&efx->filter_lock);
+	down_write(&state->lock);
 
 	for (table_id = 0; table_id < EFX_FARCH_FILTER_TABLE_COUNT; table_id++) {
 		table = &state->table[table_id];
@@ -2770,7 +2769,7 @@ void efx_farch_filter_table_restore(struct efx_nic *efx)
 	efx_farch_filter_push_rx_config(efx);
 	efx_farch_filter_push_tx_limits(efx);
 
-	spin_unlock_bh(&efx->filter_lock);
+	up_write(&state->lock);
 }
 
 void efx_farch_filter_table_remove(struct efx_nic *efx)
@@ -2864,7 +2863,7 @@ void efx_farch_filter_update_rx_scatter(struct efx_nic *efx)
 	efx_oword_t filter;
 	unsigned int filter_idx;
 
-	spin_lock_bh(&efx->filter_lock);
+	down_write(&state->lock);
 
 	for (table_id = EFX_FARCH_FILTER_TABLE_RX_IP;
 	     table_id <= EFX_FARCH_FILTER_TABLE_RX_DEF;
@@ -2896,33 +2895,30 @@ void efx_farch_filter_update_rx_scatter(struct efx_nic *efx)
 
 	efx_farch_filter_push_rx_config(efx);
 
-	spin_unlock_bh(&efx->filter_lock);
+	up_write(&state->lock);
 }
 
 #ifdef CONFIG_RFS_ACCEL
 
-s32 efx_farch_filter_rfs_insert(struct efx_nic *efx,
-				struct efx_filter_spec *gen_spec)
-{
-	return efx_farch_filter_insert(efx, gen_spec, true);
-}
-
 bool efx_farch_filter_rfs_expire_one(struct efx_nic *efx, u32 flow_id,
 				     unsigned int index)
 {
 	struct efx_farch_filter_state *state = efx->filter_state;
-	struct efx_farch_filter_table *table =
-		&state->table[EFX_FARCH_FILTER_TABLE_RX_IP];
+	struct efx_farch_filter_table *table;
+	bool ret = false;
 
+	down_write(&state->lock);
+	table = &state->table[EFX_FARCH_FILTER_TABLE_RX_IP];
 	if (test_bit(index, table->used_bitmap) &&
 	    table->spec[index].priority == EFX_FILTER_PRI_HINT &&
 	    rps_may_expire_flow(efx->net_dev, table->spec[index].dmaq_id,
 				flow_id, index)) {
 		efx_farch_filter_table_clear_entry(efx, table, index);
-		return true;
+		ret = true;
 	}
 
-	return false;
+	up_write(&state->lock);
+	return ret;
 }
 
 #endif /* CONFIG_RFS_ACCEL */