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net/mlx5: Fix possible deadlock from lockdep when adding fte to fg

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This is a false positive report due to incorrect nested lock
annotations as we lock multiple fgs with the same subclass.
Instead of locking all fgs only lock the one being used as was
done before.

Fixes: bd71b08ec2 ("net/mlx5: Support multiple updates of steering rules in parallel")
Signed-off-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
This commit is contained in:
Roi Dayan 2018-08-20 11:43:03 +03:00 committed by Saeed Mahameed
parent fc433829f9
commit ad9421e36a
1 changed files with 37 additions and 37 deletions
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74
drivers/net/ethernet/mellanox/mlx5/core/fs_core.c
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@ -1578,6 +1578,33 @@ static u64 matched_fgs_get_version(struct list_head *match_head)
return version;
}
static struct fs_fte *
lookup_fte_locked(struct mlx5_flow_group *g,
u32 *match_value,
bool take_write)
{
struct fs_fte *fte_tmp;
if (take_write)
nested_down_write_ref_node(&g->node, FS_LOCK_PARENT);
else
nested_down_read_ref_node(&g->node, FS_LOCK_PARENT);
fte_tmp = rhashtable_lookup_fast(&g->ftes_hash, match_value,
rhash_fte);
if (!fte_tmp || !tree_get_node(&fte_tmp->node)) {
fte_tmp = NULL;
goto out;
}
nested_down_write_ref_node(&fte_tmp->node, FS_LOCK_CHILD);
out:
if (take_write)
up_write_ref_node(&g->node);
else
up_read_ref_node(&g->node);
return fte_tmp;
}
static struct mlx5_flow_handle *
try_add_to_existing_fg(struct mlx5_flow_table *ft,
struct list_head *match_head,
@ -1600,10 +1627,6 @@ try_add_to_existing_fg(struct mlx5_flow_table *ft,
if (IS_ERR(fte))
return ERR_PTR(-ENOMEM);
list_for_each_entry(iter, match_head, list) {
nested_down_read_ref_node(&iter->g->node, FS_LOCK_PARENT);
}
search_again_locked:
version = matched_fgs_get_version(match_head);
/* Try to find a fg that already contains a matching fte */
@ -1611,20 +1634,9 @@ search_again_locked:
struct fs_fte *fte_tmp;
g = iter->g;
fte_tmp = rhashtable_lookup_fast(&g->ftes_hash, spec->match_value,
rhash_fte);
if (!fte_tmp || !tree_get_node(&fte_tmp->node))
fte_tmp = lookup_fte_locked(g, spec->match_value, take_write);
if (!fte_tmp)
continue;
nested_down_write_ref_node(&fte_tmp->node, FS_LOCK_CHILD);
if (!take_write) {
list_for_each_entry(iter, match_head, list)
up_read_ref_node(&iter->g->node);
} else {
list_for_each_entry(iter, match_head, list)
up_write_ref_node(&iter->g->node);
}
rule = add_rule_fg(g, spec->match_value,
flow_act, dest, dest_num, fte_tmp);
up_write_ref_node(&fte_tmp->node);
@ -1633,19 +1645,6 @@ search_again_locked:
return rule;
}
/* No group with matching fte found. Try to add a new fte to any
* matching fg.
*/
if (!take_write) {
list_for_each_entry(iter, match_head, list)
up_read_ref_node(&iter->g->node);
list_for_each_entry(iter, match_head, list)
nested_down_write_ref_node(&iter->g->node,
FS_LOCK_PARENT);
take_write = true;
}
/* Check the ft version, for case that new flow group
* was added while the fgs weren't locked
*/
@ -1657,27 +1656,30 @@ search_again_locked:
/* Check the fgs version, for case the new FTE with the
* same values was added while the fgs weren't locked
*/
if (version != matched_fgs_get_version(match_head))
if (version != matched_fgs_get_version(match_head)) {
take_write = true;
goto search_again_locked;
}
list_for_each_entry(iter, match_head, list) {
g = iter->g;
if (!g->node.active)
continue;
nested_down_write_ref_node(&g->node, FS_LOCK_PARENT);
err = insert_fte(g, fte);
if (err) {
up_write_ref_node(&g->node);
if (err == -ENOSPC)
continue;
list_for_each_entry(iter, match_head, list)
up_write_ref_node(&iter->g->node);
kmem_cache_free(steering->ftes_cache, fte);
return ERR_PTR(err);
}
nested_down_write_ref_node(&fte->node, FS_LOCK_CHILD);
list_for_each_entry(iter, match_head, list)
up_write_ref_node(&iter->g->node);
up_write_ref_node(&g->node);
rule = add_rule_fg(g, spec->match_value,
flow_act, dest, dest_num, fte);
up_write_ref_node(&fte->node);
@ -1686,8 +1688,6 @@ search_again_locked:
}
rule = ERR_PTR(-ENOENT);
out:
list_for_each_entry(iter, match_head, list)
up_write_ref_node(&iter->g->node);
kmem_cache_free(steering->ftes_cache, fte);
return rule;
}