nfp: flower: fix stats id allocation

BugLink: https://bugs.launchpad.net/bugs/1860490
[ Upstream commit 39f14c00b13c47186739a4cbc7a16e04d7fdbb60 ]

As flower rules are added, they are given a stats ID based on the number
of rules that can be supported in firmware. Only after the initial
allocation of all available IDs does the driver begin to reuse those that
have been released.

The initial allocation of IDs was modified to account for multiple memory
units on the offloaded device. However, this introduced a bug whereby the
counter that controls the IDs could be decremented before the ID was
assigned (where it is further decremented). This means that the stats ID
could be assigned as -1/0xfffffff which is out of range.

Fix this by only decrementing the main counter after the current ID has
been assigned.

Fixes: 467322e2627f ("nfp: flower: support multiple memory units for filter offloads")
Signed-off-by: John Hurley <john.hurley@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/ethernet/netronome/nfp/flower/metadata.c b/drivers/net/ethernet/netronome/nfp/flower/metadata.c
index 7c4a15e967df337b9f1591b78073a626f27b9586..5defd31d481c26a6bb650301bc4cd16c977f5cb5 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/flower/metadata.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/metadata.c
@@ -65,17 +65,17 @@ static int nfp_get_stats_entry(struct nfp_app *app, u32 *stats_context_id)
        freed_stats_id = priv->stats_ring_size;
        /* Check for unallocated entries first. */
        if (priv->stats_ids.init_unalloc > 0) {
-               if (priv->active_mem_unit == priv->total_mem_units) {
-                       priv->stats_ids.init_unalloc--;
-                       priv->active_mem_unit = 0;
-               }
-
                *stats_context_id =
                        FIELD_PREP(NFP_FL_STAT_ID_STAT,
                                   priv->stats_ids.init_unalloc - 1) |
                        FIELD_PREP(NFP_FL_STAT_ID_MU_NUM,
                                   priv->active_mem_unit);
-               priv->active_mem_unit++;
+
+               if (++priv->active_mem_unit == priv->total_mem_units) {
+                       priv->stats_ids.init_unalloc--;
+                       priv->active_mem_unit = 0;
+               }
+
                return 0;
        }