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    Subject[PATCH 4.19 499/639] cxgb4: smt: Add lock for atomic_dec_and_test
    Date
    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 7b2207a2a130f..9b3f4205cb4d4 100644
    --- 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);

    --
    2.20.1


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