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    Subject[PATCH 5.15 549/917] nfp: fix potential deadlock when canceling dim work
    Date
    From: Yinjun Zhang <yinjun.zhang@corigine.com>

    [ Upstream commit 17e712c6a1bade9dac02a7bf2b464746faa7e9a0 ]

    When port is linked down, the process which has acquired rtnl_lock
    will wait for the in-progress dim work to finish, and the work also
    acquires rtnl_lock, which may cause deadlock.

    Currently IRQ_MOD registers can be configured by `ethtool -C` and
    dim work, and which will take effect depends on the execution order,
    rtnl_lock is useless here, so remove them.

    Fixes: 9d32e4e7e9e1 ("nfp: add support for coalesce adaptive feature")
    Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
    Signed-off-by: Louis Peens <louis.peens@corigine.com>
    Signed-off-by: Simon Horman <simon.horman@corigine.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/ethernet/netronome/nfp/nfp_net_common.c | 4 ----
    1 file changed, 4 deletions(-)

    diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
    index f8b880c8e5148..850bfdf83d0a4 100644
    --- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
    +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
    @@ -3016,10 +3016,8 @@ static void nfp_net_rx_dim_work(struct work_struct *work)

    /* copy RX interrupt coalesce parameters */
    value = (moder.pkts << 16) | (factor * moder.usec);
    - rtnl_lock();
    nn_writel(nn, NFP_NET_CFG_RXR_IRQ_MOD(r_vec->rx_ring->idx), value);
    (void)nfp_net_reconfig(nn, NFP_NET_CFG_UPDATE_IRQMOD);
    - rtnl_unlock();

    dim->state = DIM_START_MEASURE;
    }
    @@ -3047,10 +3045,8 @@ static void nfp_net_tx_dim_work(struct work_struct *work)

    /* copy TX interrupt coalesce parameters */
    value = (moder.pkts << 16) | (factor * moder.usec);
    - rtnl_lock();
    nn_writel(nn, NFP_NET_CFG_TXR_IRQ_MOD(r_vec->tx_ring->idx), value);
    (void)nfp_net_reconfig(nn, NFP_NET_CFG_UPDATE_IRQMOD);
    - rtnl_unlock();

    dim->state = DIM_START_MEASURE;
    }
    --
    2.33.0


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