cxgb4: smt: Add lock for atomic_dec_and_test

[ 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>

diff --git a/drivers/net/ethernet/chelsio/cxgb4/smt.c b/drivers/net/ethernet/chelsio/cxgb4/smt.c
index 7b2207a..9b3f420 100644 (file)
--- a/drivers/net/ethernet/chelsio/cxgb4/smt.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/smt.c
@@ -98,11 +98,9 @@ found_reuse:
 
 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);