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    SubjectRE: [openib-general] Re: [PATCH][26/26] IB: MAD cancel callbacks fromthread
    Date
    >Roland Dreier wrote:
    >> +void cancel_sends(void *data)
    >> +{
    >> + struct ib_mad_agent_private *mad_agent_priv;
    >> + struct ib_mad_send_wr_private *mad_send_wr;
    >> + struct ib_mad_send_wc mad_send_wc;
    >> + unsigned long flags;
    >> +
    >> + mad_agent_priv = (struct ib_mad_agent_private *)data;
    >
    >don't add casts to a void pointer, that's silly.

    This is my bad.

    >> + mad_send_wc.status = IB_WC_WR_FLUSH_ERR;
    >> + mad_send_wc.vendor_err = 0;
    >> +
    >> + spin_lock_irqsave(&mad_agent_priv->lock, flags);
    >> + while (!list_empty(&mad_agent_priv->canceled_list)) {
    >> + mad_send_wr = list_entry(mad_agent_priv->canceled_list.next,
    >> + struct ib_mad_send_wr_private,
    >> + agent_list);
    >> +
    >> + list_del(&mad_send_wr->agent_list);
    >> + spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
    >> +
    >> + mad_send_wc.wr_id = mad_send_wr->wr_id;
    >> + mad_agent_priv->agent.send_handler(&mad_agent_priv->agent,
    >> + &mad_send_wc);
    >> +
    >> + kfree(mad_send_wr);
    >> + if (atomic_dec_and_test(&mad_agent_priv->refcount))
    >> + wake_up(&mad_agent_priv->wait);
    >> + spin_lock_irqsave(&mad_agent_priv->lock, flags);
    >> + }
    >> + spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
    >
    >dumb question... why is the lock dropped? is it just for the
    >send_handler(), or also for wr_id assigned, kfree, and wake_up() ?

    The lock is dropped to avoid calling the user back with it held. The if
    statement / wake_up call near the bottom of the loop can be replaced with a
    simple atomic_dec. The test should always fail. The lock is to protect
    access to the canceled_list.

    (Sorry about the mailer...)

    - Sean

    -
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