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    Subject[PATCH 4.19 53/69] net/smc: Dont call clcsock shutdown twice when smc shutdown
    Date
    From: Tony Lu <tonylu@linux.alibaba.com>

    [ Upstream commit bacb6c1e47691cda4a95056c21b5487fb7199fcc ]

    When applications call shutdown() with SHUT_RDWR in userspace,
    smc_close_active() calls kernel_sock_shutdown(), and it is called
    twice in smc_shutdown().

    This fixes this by checking sk_state before do clcsock shutdown, and
    avoids missing the application's call of smc_shutdown().

    Link: https://lore.kernel.org/linux-s390/1f67548e-cbf6-0dce-82b5-10288a4583bd@linux.ibm.com/
    Fixes: 606a63c9783a ("net/smc: Ensure the active closing peer first closes clcsock")
    Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
    Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
    Acked-by: Karsten Graul <kgraul@linux.ibm.com>
    Link: https://lore.kernel.org/r/20211126024134.45693-1-tonylu@linux.alibaba.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/smc/af_smc.c | 8 +++++++-
    1 file changed, 7 insertions(+), 1 deletion(-)

    diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
    index 9aab4ab8161bd..4c904ab29e0e6 100644
    --- a/net/smc/af_smc.c
    +++ b/net/smc/af_smc.c
    @@ -1589,8 +1589,10 @@ static __poll_t smc_poll(struct file *file, struct socket *sock,
    static int smc_shutdown(struct socket *sock, int how)
    {
    struct sock *sk = sock->sk;
    + bool do_shutdown = true;
    struct smc_sock *smc;
    int rc = -EINVAL;
    + int old_state;
    int rc1 = 0;

    smc = smc_sk(sk);
    @@ -1617,7 +1619,11 @@ static int smc_shutdown(struct socket *sock, int how)
    }
    switch (how) {
    case SHUT_RDWR: /* shutdown in both directions */
    + old_state = sk->sk_state;
    rc = smc_close_active(smc);
    + if (old_state == SMC_ACTIVE &&
    + sk->sk_state == SMC_PEERCLOSEWAIT1)
    + do_shutdown = false;
    break;
    case SHUT_WR:
    rc = smc_close_shutdown_write(smc);
    @@ -1627,7 +1633,7 @@ static int smc_shutdown(struct socket *sock, int how)
    /* nothing more to do because peer is not involved */
    break;
    }
    - if (smc->clcsock)
    + if (do_shutdown && smc->clcsock)
    rc1 = kernel_sock_shutdown(smc->clcsock, how);
    /* map sock_shutdown_cmd constants to sk_shutdown value range */
    sk->sk_shutdown |= how + 1;
    --
    2.33.0


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