[PATCH 5.4 159/165] net/mlx5: DR, No need for atomic refcount for internal SW steering resources

Greg Kroah-Hartman
2020-01-11T10:34:19Z

From: Yevgeny Kliteynik <kliteyn@mellanox.com>

[ Upstream commit 4ce380ca477507e2f413584cdd99e1698d6682d6 ]

No need for an atomic refcounter for the STE and hashtables.
These are internal SW steering resources and they are always
under domain mutex.

This also fixes the following refcount error:
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 9 PID: 3527 at lib/refcount.c:25 refcount_warn_saturate+0x81/0xe0
Call Trace:
dr_table_init_nic+0x10d/0x110 [mlx5_core]
mlx5dr_table_create+0xb4/0x230 [mlx5_core]
mlx5_cmd_dr_create_flow_table+0x39/0x120 [mlx5_core]
__mlx5_create_flow_table+0x221/0x5f0 [mlx5_core]
esw_create_offloads_fdb_tables+0x180/0x5a0 [mlx5_core]
...

Fixes: 26d688e33f88 ("net/mlx5: DR, Add Steering entry (STE) utilities")
Signed-off-by: Yevgeny Kliteynik <kliteyn@mellanox.com>
Reviewed-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c | 2 -
drivers/net/ethernet/mellanox/mlx5/core/steering/dr_ste.c | 10 ++++----
drivers/net/ethernet/mellanox/mlx5/core/steering/dr_types.h | 14 ++++++------
3 files changed, 14 insertions(+), 12 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_rule.c
@@ -209,7 +209,7 @@ static void dr_rule_rehash_copy_ste_ctrl
/* We need to copy the refcount since this ste
* may have been traversed several times
*/
- refcount_set(&new_ste->refcount, refcount_read(&cur_ste->refcount));
+ new_ste->refcount = cur_ste->refcount;

/* Link old STEs rule_mem list to the new ste */
mlx5dr_rule_update_rule_member(cur_ste, new_ste);
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_ste.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_ste.c
@@ -340,7 +340,7 @@ static void dr_ste_replace(struct mlx5dr
if (dst->next_htbl)
dst->next_htbl->pointing_ste = dst;

- refcount_set(&dst->refcount, refcount_read(&src->refcount));
+ dst->refcount = src->refcount;

INIT_LIST_HEAD(&dst->rule_list);
list_splice_tail_init(&src->rule_list, &dst->rule_list);
@@ -557,7 +557,7 @@ bool mlx5dr_ste_is_not_valid_entry(u8 *p

bool mlx5dr_ste_not_used_ste(struct mlx5dr_ste *ste)
{
- return !refcount_read(&ste->refcount);
+ return !ste->refcount;
}

/* Init one ste as a pattern for ste data array */
@@ -681,14 +681,14 @@ struct mlx5dr_ste_htbl *mlx5dr_ste_htbl_
htbl->ste_arr = chunk->ste_arr;
htbl->hw_ste_arr = chunk->hw_ste_arr;
htbl->miss_list = chunk->miss_list;
- refcount_set(&htbl->refcount, 0);
+ htbl->refcount = 0;

for (i = 0; i < chunk->num_of_entries; i++) {
struct mlx5dr_ste *ste = &htbl->ste_arr[i];

ste->hw_ste = htbl->hw_ste_arr + i * DR_STE_SIZE_REDUCED;
ste->htbl = htbl;
- refcount_set(&ste->refcount, 0);
+ ste->refcount = 0;
INIT_LIST_HEAD(&ste->miss_list_node);
INIT_LIST_HEAD(&htbl->miss_list[i]);
INIT_LIST_HEAD(&ste->rule_list);
@@ -705,7 +705,7 @@ out_free_htbl:

int mlx5dr_ste_htbl_free(struct mlx5dr_ste_htbl *htbl)
{
- if (refcount_read(&htbl->refcount))
+ if (htbl->refcount)
return -EBUSY;

mlx5dr_icm_free_chunk(htbl->chunk);
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_types.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_types.h
@@ -117,7 +117,7 @@ struct mlx5dr_matcher_rx_tx;
struct mlx5dr_ste {
u8 *hw_ste;
/* refcount: indicates the num of rules that using this ste */
- refcount_t refcount;
+ u32 refcount;

/* attached to the miss_list head at each htbl entry */
struct list_head miss_list_node;
@@ -149,7 +149,7 @@ struct mlx5dr_ste_htbl_ctrl {
struct mlx5dr_ste_htbl {
u8 lu_type;
u16 byte_mask;
- refcount_t refcount;
+ u32 refcount;
struct mlx5dr_icm_chunk *chunk;
struct mlx5dr_ste *ste_arr;
u8 *hw_ste_arr;
@@ -200,13 +200,14 @@ int mlx5dr_ste_htbl_free(struct mlx5dr_s

static inline void mlx5dr_htbl_put(struct mlx5dr_ste_htbl *htbl)
{
- if (refcount_dec_and_test(&htbl->refcount))
+ htbl->refcount--;
+ if (!htbl->refcount)
mlx5dr_ste_htbl_free(htbl);
}

static inline void mlx5dr_htbl_get(struct mlx5dr_ste_htbl *htbl)
{
- refcount_inc(&htbl->refcount);
+ htbl->refcount++;
}

/* STE utils */
@@ -248,14 +249,15 @@ static inline void mlx5dr_ste_put(struct
struct mlx5dr_matcher *matcher,
struct mlx5dr_matcher_rx_tx *nic_matcher)
{
- if (refcount_dec_and_test(&ste->refcount))
+ ste->refcount--;
+ if (!ste->refcount)
mlx5dr_ste_free(ste, matcher, nic_matcher);
}

/* initial as 0, increased only when ste appears in a new rule */
static inline void mlx5dr_ste_get(struct mlx5dr_ste *ste)
{
- refcount_inc(&ste->refcount);
+ ste->refcount++;
}

void mlx5dr_ste_set_hit_addr_by_next_htbl(u8 *hw_ste,