On Fri, Jun 4, 2010 at 1:21 PM, Mike Heinz <[email protected]> wrote:
> The purpose of this patch is to cause the ib_mad driver to discard busy
> responses from the SA, effectively causing busy responses to become time outs.
>
> This ensures that naïve IB applications cannot overwhelm the SA with queries,
> which could happen when a cluster is being rebooted, or when a large HPC
> application is started.
>
> Note that this patch directly changes the same code affected by the mad user
> rmpp patch - it cannot be successfully applied without that patch.
>
> Signed-Off-By: Michael Heinz <[email protected]>
>
> ----
>
> diff --git a/drivers/infiniband/core/mad.c b/drivers/infiniband/core/mad.c
> index efca783..05f2930 100644
> --- a/drivers/infiniband/core/mad.c
> +++ b/drivers/infiniband/core/mad.c
> @@ -1815,9 +1815,20 @@ static void ib_mad_complete_recv(struct
> ib_mad_agent_private *mad_agent_priv,
> */
> /* Complete corresponding request */
> if (ib_response_mad(mad_recv_wc->recv_buf.mad)) {
> + u16 busy =
> __be16_to_cpu(mad_recv_wc->recv_buf.mad->mad_hdr.status) &
> + IB_MGMT_MAD_STATUS_BUSY;
> +
Would be slightly more efficient to do this in network endian (at compile time).
> spin_lock_irqsave(&mad_agent_priv->lock, flags);
> mad_send_wr = ib_find_send_mad(mad_agent_priv, mad_recv_wc);
> if (mad_send_wr) {
> + if (busy && mad_send_wr->retries_left) {
> + /* Just let the query timeout and have it
> requeued later */
Should a busy be retried at all at the mad layer ? Is a "special"
(longer) timeout policy for busy needed ?
Also, should this be done for all MADs classified by ib_response_mad
(e.g. trap represses) ?
-- Hal
> + spin_unlock_irqrestore(&mad_agent_priv->lock,
> flags);
> + ib_free_recv_mad(mad_recv_wc);
> + deref_mad_agent(mad_agent_priv);
> + printk(KERN_NOTICE PFX "Response returned
> with MAD_STATUS_BUSY\n");
> + return;
> + }
> ib_mark_mad_done(mad_send_wr);
> spin_unlock_irqrestore(&mad_agent_priv->lock, flags);
>
> diff --git a/include/rdma/ib_mad.h b/include/rdma/ib_mad.h
> index 2651e93..e9dc4cc 100644
> --- a/include/rdma/ib_mad.h
> +++ b/include/rdma/ib_mad.h
> @@ -77,6 +77,15 @@
>
> #define IB_MGMT_MAX_METHODS 128
>
> +/* MAD Status field bit masks */
> +#define IB_MGMT_MAD_STATUS_SUCCESS
> 0x0000
> +#define IB_MGMT_MAD_STATUS_BUSY
> 0x0001
> +#define IB_MGMT_MAD_STATUS_REDIRECT_REQD 0x0002
> +#define IB_MGMT_MAD_STATUS_BAD_VERERSION 0x0004
> +#define IB_MGMT_MAD_STATUS_UNSUPPORTED_METHOD 0x0008
> +#define IB_MGMT_MAD_STATUS_UNSUPPORTED_METHOD_ATTRIB 0x000c
> +#define IB_MGMT_MAD_STATUS_INVALID_ATTRIB_VALUE 0x001c
> +
> /* RMPP information */
> #define IB_MGMT_RMPP_VERSION 1
> #define IB_MGMT_RMPP_PASSTHRU 255
> --
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