[SPDK] Destroy QP process in nvmf

[Vikas Gupta <vikas.gupta at broadcom.com>]

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Hi,

I would like to draw attention in destroy QP process in nvmf that there is
possibility that requests could be processed even after destroy QP in one
of the scenario.

When a disk (hot plug) is removed from the target the related subsystem is
paused and in fly requests are queued as below in nvmf/request.c



  */* Check if the subsystem is paused (if there is a subsystem) */*

*        if (qpair->ctrlr) {*

*                struct spdk_nvmf_subsystem_poll_group *sgroup =
&qpair->group->sgroups[qpair->ctrlr->subsys->id];*

*                if (sgroup->state != SPDK_NVMF_SUBSYSTEM_ACTIVE) {*

*                        /* The subsystem is not currently active. Queue
this request. */*

*                        TAILQ_INSERT_TAIL(&sgroup->queued, req, link);*

*                        return;*

*                }*



*        } *



By the time system is resumed the QP would have been destroyed and we may
still process the stale QP`s requests with below code in nvmf.c function
spdk_nvmf_poll_group_resume_subsystem().



*        /* Release all queued requests */*

*        TAILQ_FOREACH_SAFE(req, &sgroup->queued, link, tmp) {*

*                TAILQ_REMOVE(&sgroup->queued, req, link);*

*                spdk_nvmf_request_exec(req);*

*        }              *



I think we should remove the stale QP requests from the sgroup`s queue
before we destroy the QP.

Please let me know if my understanding is correct.





Thanks,

Vikas