sfc: Limit filter search depth further for performance hints (i.e. RFS)

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/net/sfc/filter.c b/drivers/net/sfc/filter.c
index d4722c41c4ce..47a1b7984788 100644
--- a/drivers/net/sfc/filter.c
+++ b/drivers/net/sfc/filter.c
@@ -27,6 +27,10 @@
  */
 #define FILTER_CTL_SRCH_MAX 200
 
+/* Don't try very hard to find space for performance hints, as this is
+ * counter-productive. */
+#define FILTER_CTL_SRCH_HINT_MAX 5
+
 enum efx_filter_table_id {
         EFX_FILTER_TABLE_RX_IP = 0,
         EFX_FILTER_TABLE_RX_MAC,
@@ -325,15 +329,16 @@ static int efx_filter_search(struct efx_filter_table *table,
                              struct efx_filter_spec *spec, u32 key,
                              bool for_insert, int *depth_required)
 {
-        unsigned hash, incr, filter_idx, depth;
+        unsigned hash, incr, filter_idx, depth, depth_max;
         struct efx_filter_spec *cmp;
 
         hash = efx_filter_hash(key);
         incr = efx_filter_increment(key);
+        depth_max = (spec->priority <= EFX_FILTER_PRI_HINT ?
+                     FILTER_CTL_SRCH_HINT_MAX : FILTER_CTL_SRCH_MAX);
 
         for (depth = 1, filter_idx = hash & (table->size - 1);
-             depth <= FILTER_CTL_SRCH_MAX &&
-                     test_bit(filter_idx, table->used_bitmap);
+             depth <= depth_max && test_bit(filter_idx, table->used_bitmap);
              ++depth) {
                 cmp = &table->spec[filter_idx];
                 if (efx_filter_equal(spec, cmp))
@@ -342,7 +347,7 @@ static int efx_filter_search(struct efx_filter_table *table,
         }
         if (!for_insert)
                 return -ENOENT;
-        if (depth > FILTER_CTL_SRCH_MAX)
+        if (depth > depth_max)
                 return -EBUSY;
 found:
         *depth_required = depth;