[PATCH 4.8 24/49] mlxsw: spectrum: Fix refcount bug on span entries

From: Greg Kroah-Hartman
Date: Sat Nov 19 2016 - 04:26:08 EST


4.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Yotam Gigi <yotamg@xxxxxxxxxxxx>


[ Upstream commit 2d644d4c7506646f9c4a2afceb7fd5f030bc0c9f ]

When binding port to a newly created span entry, its refcount is
initialized to zero even though it has a bound port. That leads
to unexpected behaviour when the user tries to delete that port
from the span entry.

Fix this by initializing the reference count to 1.

Also add a warning to put function.

Fixes: 763b4b70afcd ("mlxsw: spectrum: Add support in matchall mirror TC offloading")
Signed-off-by: Yotam Gigi <yotamg@xxxxxxxxxxxx>
Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxxxx>
Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c
@@ -231,7 +231,7 @@ mlxsw_sp_span_entry_create(struct mlxsw_

span_entry->used = true;
span_entry->id = index;
- span_entry->ref_count = 0;
+ span_entry->ref_count = 1;
span_entry->local_port = local_port;
return span_entry;
}
@@ -268,6 +268,7 @@ struct mlxsw_sp_span_entry *mlxsw_sp_spa

span_entry = mlxsw_sp_span_entry_find(port);
if (span_entry) {
+ /* Already exists, just take a reference */
span_entry->ref_count++;
return span_entry;
}
@@ -278,6 +279,7 @@ struct mlxsw_sp_span_entry *mlxsw_sp_spa
static int mlxsw_sp_span_entry_put(struct mlxsw_sp *mlxsw_sp,
struct mlxsw_sp_span_entry *span_entry)
{
+ WARN_ON(!span_entry->ref_count);
if (--span_entry->ref_count == 0)
mlxsw_sp_span_entry_destroy(mlxsw_sp, span_entry);
return 0;