[PATCH AUTOSEL 4.19 485/671] cxgb4: smt: Add lock for atomic_dec_and_test

Sasha Levin
2020-01-16T18:46:16Z

From: Chuhong Yuan <hslester96@gmail.com>

[ Upstream commit 4a8937b83892cb69524291cae6cdabad4a8be033 ]

The atomic_dec_and_test() is not safe because it is
outside of locks.
Move the locks of t4_smte_free() to its caller,
cxgb4_smt_release() to protect the atomic decrement.

Fixes: 3bdb376e6944 ("cxgb4: introduce SMT ops to prepare for SMAC rewrite support")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/chelsio/cxgb4/smt.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/smt.c b/drivers/net/ethernet/chelsio/cxgb4/smt.c
index 7b2207a2a130..9b3f4205cb4d 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/smt.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/smt.c
@@ -98,11 +98,9 @@ static struct smt_entry *find_or_alloc_smte(struct smt_data *s, u8 *smac)

static void t4_smte_free(struct smt_entry *e)
{
- spin_lock_bh(&e->lock);
if (atomic_read(&e->refcnt) == 0) { /* hasn't been recycled */
e->state = SMT_STATE_UNUSED;
}
- spin_unlock_bh(&e->lock);
}

/**
@@ -112,8 +110,10 @@ static void t4_smte_free(struct smt_entry *e)
*/
void cxgb4_smt_release(struct smt_entry *e)
{
+ spin_lock_bh(&e->lock);
if (atomic_dec_and_test(&e->refcnt))
t4_smte_free(e);
+ spin_unlock_bh(&e->lock);
}
EXPORT_SYMBOL(cxgb4_smt_release);

--
2.20.1