Re: [PATCH V4 for-next 02/10] IB/core: Introduce Work Queue object and its verbs

On 5/23/2016 7:20 AM, Yishai Hadas wrote:

Introduce Work Queue object and its create/destroy/modify verbs.

QP can be created without internal WQs "packaged" inside it,
this QP can be configured to use "external" WQ object as its
receive/send queue.
WQ is a necessary component for RSS technology since RSS mechanism
is supposed to distribute the traffic between multiple
Receive Work Queues.

WQ associated (many to one) with Completion Queue and it owns WQ
properties (PD, WQ size, etc.).
WQ has a type, this patch introduces the IB_WQT_RQ (i.e.receive queue),
it may be extend to others such as IB_WQT_SQ. (send queue).
WQ from type IB_WQT_RQ contains receive work requests.

PD is an attribute of a work queue (i.e. send/receive queue), it's used
by the hardware for security validation before scattering to a memory
region which is pointed by the WQ. For that, an external WQ object
needs a PD, letting the hardware makes that validation.

When accessing a memory region that is pointed by the WQ its PD
is used and not the QP's PD, this behavior is similar
to a SRQ and a QP.

WQ context is subject to a well-defined state transitions done by
the modify_wq verb.
When WQ is created its initial state becomes IB_WQS_RESET.

quoted

From IB_WQS_RESET it can be modified to itself or to IB_WQS_RDY.
From IB_WQS_RDY it can be modified to itself, to IB_WQS_RESET

or to IB_WQS_ERR.

quoted

From IB_WQS_ERR it can be modified to IB_WQS_RESET.

Note: transition to IB_WQS_ERR might occur implicitly in case there
was some HW error.

Hey Yishai,

What happens to posted RQ WRs when transitioning from RDY->RESET, 
RDY->ERR, and ERR->RESET?
Shouldn't the state machine be defined more?

Steve.

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