sfc: Don't try to set filters with search depths we know won't work

The filter engine will time-out and ignore filters beyond
200-something hops.  We also need to avoid infinite loops in
efx_filter_search() when the table is full.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/net/sfc/filter.c b/drivers/net/sfc/filter.c
index abc884d09d57..52cb6082b910 100644
--- a/drivers/net/sfc/filter.c
+++ b/drivers/net/sfc/filter.c
@@ -20,6 +20,12 @@
 #define FILTER_CTL_SRCH_FUDGE_WILD 3
 #define FILTER_CTL_SRCH_FUDGE_FULL 1
 
+/* Hard maximum hop limit.  Hardware will time-out beyond 200-something.
+ * We also need to avoid infinite loops in efx_filter_search() when the
+ * table is full.
+ */
+#define FILTER_CTL_SRCH_MAX 200
+
 struct efx_filter_table {
         u32             offset;         /* address of table relative to BAR */
         unsigned        size;           /* number of entries */
@@ -183,7 +189,8 @@ static int efx_filter_search(struct efx_filter_table *table,
         incr = efx_filter_increment(key);
 
         for (depth = 1, filter_idx = hash & (table->size - 1);
-             test_bit(filter_idx, table->used_bitmap);
+             depth <= FILTER_CTL_SRCH_MAX &&
+                     test_bit(filter_idx, table->used_bitmap);
              ++depth) {
                 cmp = &table->spec[filter_idx];
                 if (efx_filter_equal(spec, cmp))
@@ -192,6 +199,8 @@ static int efx_filter_search(struct efx_filter_table *table,
         }
         if (!for_insert)
                 return -ENOENT;
+        if (depth > FILTER_CTL_SRCH_MAX)
+                return -EBUSY;
 found:
         *depth_required = depth;
         return filter_idx;