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authorVlad Buslov <vladbu@mellanox.com>2019-06-13 17:54:04 +0300
committerDavid S. Miller <davem@davemloft.net>2019-06-14 19:29:57 -0700
commit99815f5031db36414178f45e3009fb5f0e219dd4 (patch)
tree3315f9e1d75ea2f8a030260f42a4bb626b6d3593 /net/sched
parentf0c03ee0ec664e07e0ec1ead7091cbe53f0f321c (diff)
downloadlinux-99815f5031db36414178f45e3009fb5f0e219dd4.tar.bz2
net: sched: flower: don't call synchronize_rcu() on mask creation
Current flower mask creating code assumes that temporary mask that is used when inserting new filter is stack allocated. To prevent race condition with data patch synchronize_rcu() is called every time fl_create_new_mask() replaces temporary stack allocated mask. As reported by Jiri, this increases runtime of creating 20000 flower classifiers from 4 seconds to 163 seconds. However, this design is no longer necessary since temporary mask was converted to be dynamically allocated by commit 2cddd2014782 ("net/sched: cls_flower: allocate mask dynamically in fl_change()"). Remove synchronize_rcu() calls from mask creation code. Instead, refactor fl_change() to always deallocate temporary mask with rcu grace period. Fixes: 195c234d15c9 ("net: sched: flower: handle concurrent mask insertion") Reported-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: Vlad Buslov <vladbu@mellanox.com> Tested-by: Jiri Pirko <jiri@mellanox.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched')
-rw-r--r--net/sched/cls_flower.c34
1 files changed, 18 insertions, 16 deletions
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index c388372df0e2..eedd5786c084 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -320,10 +320,13 @@ static int fl_init(struct tcf_proto *tp)
return rhashtable_init(&head->ht, &mask_ht_params);
}
-static void fl_mask_free(struct fl_flow_mask *mask)
+static void fl_mask_free(struct fl_flow_mask *mask, bool mask_init_done)
{
- WARN_ON(!list_empty(&mask->filters));
- rhashtable_destroy(&mask->ht);
+ /* temporary masks don't have their filters list and ht initialized */
+ if (mask_init_done) {
+ WARN_ON(!list_empty(&mask->filters));
+ rhashtable_destroy(&mask->ht);
+ }
kfree(mask);
}
@@ -332,7 +335,15 @@ static void fl_mask_free_work(struct work_struct *work)
struct fl_flow_mask *mask = container_of(to_rcu_work(work),
struct fl_flow_mask, rwork);
- fl_mask_free(mask);
+ fl_mask_free(mask, true);
+}
+
+static void fl_uninit_mask_free_work(struct work_struct *work)
+{
+ struct fl_flow_mask *mask = container_of(to_rcu_work(work),
+ struct fl_flow_mask, rwork);
+
+ fl_mask_free(mask, false);
}
static bool fl_mask_put(struct cls_fl_head *head, struct fl_flow_mask *mask)
@@ -1346,9 +1357,6 @@ static struct fl_flow_mask *fl_create_new_mask(struct cls_fl_head *head,
if (err)
goto errout_destroy;
- /* Wait until any potential concurrent users of mask are finished */
- synchronize_rcu();
-
spin_lock(&head->masks_lock);
list_add_tail_rcu(&newmask->list, &head->masks);
spin_unlock(&head->masks_lock);
@@ -1375,11 +1383,7 @@ static int fl_check_assign_mask(struct cls_fl_head *head,
/* Insert mask as temporary node to prevent concurrent creation of mask
* with same key. Any concurrent lookups with same key will return
- * -EAGAIN because mask's refcnt is zero. It is safe to insert
- * stack-allocated 'mask' to masks hash table because we call
- * synchronize_rcu() before returning from this function (either in case
- * of error or after replacing it with heap-allocated mask in
- * fl_create_new_mask()).
+ * -EAGAIN because mask's refcnt is zero.
*/
fnew->mask = rhashtable_lookup_get_insert_fast(&head->ht,
&mask->ht_node,
@@ -1414,8 +1418,6 @@ static int fl_check_assign_mask(struct cls_fl_head *head,
errout_cleanup:
rhashtable_remove_fast(&head->ht, &mask->ht_node,
mask_ht_params);
- /* Wait until any potential concurrent users of mask are finished */
- synchronize_rcu();
return ret;
}
@@ -1644,7 +1646,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
*arg = fnew;
kfree(tb);
- kfree(mask);
+ tcf_queue_work(&mask->rwork, fl_uninit_mask_free_work);
return 0;
errout_ht:
@@ -1664,7 +1666,7 @@ errout:
errout_tb:
kfree(tb);
errout_mask_alloc:
- kfree(mask);
+ tcf_queue_work(&mask->rwork, fl_uninit_mask_free_work);
errout_fold:
if (fold)
__fl_put(fold);