[PATCH net] net/sched: cls_flower: allocate mask dynamically in fl_change()

[Ivan Vecera]

Recent changes (especially 05cd271fd61a ("cls_flower: Support multiple
masks per priority")) in the fl_flow_mask structure grow it and its
current size e.g. on x86_64 with defconfig is 760 bytes and more than
1024 bytes with some debug options enabled. Prior the mentioned commit
its size was 176 bytes (using defconfig on x86_64).
With regard to this fact it's reasonable to allocate this structure
dynamically in fl_change() to reduce its stack size.

Fixes: 05cd271fd61a ("cls_flower: Support multiple masks per priority")
Cc: Jiri Pirko <j...@resnulli.us>
Cc: Paul Blakey <pa...@mellanox.com>
Signed-off-by: Ivan Vecera <ivec...@redhat.com>
---
 net/sched/cls_flower.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index dad04e710493..47ac88cc34fb 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1291,16 +1291,22 @@ static int fl_change(struct net *net, struct sk_buff 
*in_skb,
        struct cls_fl_filter *fold = *arg;
        struct cls_fl_filter *fnew;
        struct nlattr **tb;
-       struct fl_flow_mask mask = {};
+       struct fl_flow_mask *mask;
        int err;
 
        if (!tca[TCA_OPTIONS])
                return -EINVAL;
 
-       tb = kcalloc(TCA_FLOWER_MAX + 1, sizeof(struct nlattr *), GFP_KERNEL);
-       if (!tb)
+       mask = kcalloc(1, sizeof(struct fl_flow_mask), GFP_KERNEL);
+       if (!mask)
                return -ENOBUFS;
 
+       tb = kcalloc(TCA_FLOWER_MAX + 1, sizeof(struct nlattr *), GFP_KERNEL);
+       if (!tb) {
+               err = -ENOBUFS;
+               goto errout_mask_alloc;
+       }
+
        err = nla_parse_nested(tb, TCA_FLOWER_MAX, tca[TCA_OPTIONS],
                               fl_policy, NULL);
        if (err < 0)
@@ -1343,12 +1349,12 @@ static int fl_change(struct net *net, struct sk_buff 
*in_skb,
                }
        }
 
-       err = fl_set_parms(net, tp, fnew, &mask, base, tb, tca[TCA_RATE], ovr,
+       err = fl_set_parms(net, tp, fnew, mask, base, tb, tca[TCA_RATE], ovr,
                           tp->chain->tmplt_priv, extack);
        if (err)
                goto errout_idr;
 
-       err = fl_check_assign_mask(head, fnew, fold, &mask);
+       err = fl_check_assign_mask(head, fnew, fold, mask);
        if (err)
                goto errout_idr;
 
@@ -1392,6 +1398,7 @@ static int fl_change(struct net *net, struct sk_buff 
*in_skb,
        }
 
        kfree(tb);
+       kfree(mask);
        return 0;
 
 errout_mask:
@@ -1405,6 +1412,8 @@ static int fl_change(struct net *net, struct sk_buff 
*in_skb,
        kfree(fnew);
 errout_tb:
        kfree(tb);
+errout_mask_alloc:
+       kfree(mask);
        return err;
 }
 
-- 
2.19.2