[dpdk-dev] [PATCH v10 05/19] eal: enable hotplug on multi-process

[Burakov, Anatoly]

On 09-Jul-18 4:36 AM, Qi Zhang wrote:
> We are going to introduce the solution to handle hotplug in
> multi-process, it includes the below scenario:
> 
> 1. Attach a device from the primary
> 2. Detach a device from the primary
> 3. Attach a device from a secondary
> 4. Detach a device from a secondary
> 
> In the primary-secondary process model, we assume devices are shared
> by default. that means attaches or detaches a device on any process
> will broadcast to all other processes through mp channel then device
> information will be synchronized on all processes.
> 
> Any failure during attaching/detaching process will cause inconsistent
> status between processes, so proper rollback action should be considered.
> 
> This patch covers the implementation of case 1,2.
> Case 3,4 will be implemented on a separate patch.
> 
> IPC scenario for Case 1, 2:
> 
> attach a device
> a) primary attach the new device if failed goto h).
> b) primary send attach sync request to all secondary.
> c) secondary receive request and attach the device and send a reply.
> d) primary check the reply if all success goes to i).
> e) primary send attach rollback sync request to all secondary.
> f) secondary receive the request and detach the device and send a reply.
> g) primary receive the reply and detach device as rollback action.
> h) attach fail
> i) attach success
> 
> detach a device
> a) primary send detach sync request to all secondary
> b) secondary detach the device and send reply
> c) primary check the reply if all success goes to f).
> d) primary send detach rollback sync request to all secondary.
> e) secondary receive the request and attach back device. goto g)
> f) primary detach the device if success goto g), else goto d)
> g) detach fail.
> h) detach success.
> 
> Signed-off-by: Qi Zhang <qi.z.zhang at intel.com>
> ---

<snip>

> +	req.t = EAL_DEV_REQ_TYPE_ATTACH;
> +	strlcpy(req.busname, busname, RTE_BUS_NAME_MAX_LEN);
> +	strlcpy(req.devname, devname, RTE_DEV_NAME_MAX_LEN);
> +	strlcpy(req.devargs, devargs, RTE_DEV_ARGS_MAX_LEN);
> +
> +	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> +		return -ENOTSUP;

Nitpick, but maybe do this before strlcpy?

> +
> +	/**
> +	 * attach a device from primary start from here:
> +	 *
> +	 * a) primary attach the new device if failed goto h).
> +	 * b) primary send attach sync request to all secondary.
> +	 * c) secondary receive request and attach the device and send a reply.
> +	 * d) primary check the reply if all success goes to i).

<snip>

> +
> +	memset(&req, 0, sizeof(req));
> +	req.t = EAL_DEV_REQ_TYPE_DETACH;
> +	strlcpy(req.busname, busname, RTE_BUS_NAME_MAX_LEN);
> +	strlcpy(req.devname, devname, RTE_DEV_NAME_MAX_LEN);
> +
> +	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> +		return -ENOTSUP;

Same nitpick, probably move this above.

> +
> +	/**
> +	 * detach a device from primary start from here:
> +	 *
> +	 * a) primary send detach sync request to all secondary
> +	 * b) secondary detach the device and send reply

<snip>

> +	struct mp_reply_bundle *bundle = param;
> +	struct rte_mp_msg *msg = &bundle->msg;
> +	const struct eal_dev_mp_req *req =
> +		(const struct eal_dev_mp_req *)msg->param;
> +	struct rte_mp_msg mp_resp;
> +	struct eal_dev_mp_req *resp =
> +		(struct eal_dev_mp_req *)mp_resp.param;
> +	int ret = 0;
> +
> +	memset(&mp_resp, 0, sizeof(mp_resp));
> +
> +	switch (req->t) {
> +	case EAL_DEV_REQ_TYPE_ATTACH:
> +	case EAL_DEV_REQ_TYPE_DETACH_ROLLBACK:
> +		ret = do_dev_hotplug_add(req->busname, req->devname, "");

I'm not too familiar with devargs and hotplug, but why are we passing 
empty devargs string here? Is it possible for it to be not empty?

> +		break;
> +	case EAL_DEV_REQ_TYPE_DETACH:
> +	case EAL_DEV_REQ_TYPE_ATTACH_ROLLBACK:
> +		ret = do_dev_hotplug_remove(req->busname, req->devname);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}

<snip>

> +	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
> +		ret = rte_mp_action_register(EAL_DEV_MP_ACTION_REQUEST,
> +					handle_secondary_request);
> +		if (ret) {
> +			RTE_LOG(ERR, EAL, "Couldn't register '%s' action\n",
> +				EAL_DEV_MP_ACTION_REQUEST);
> +			return ret;
> +		}
> +	} else {
> +		ret = rte_mp_action_register(EAL_DEV_MP_ACTION_REQUEST,
> +		handle_primary_request);

^^ wrong indentation.

> +		if (ret) {
> +			RTE_LOG(ERR, EAL, "Couldn't register '%s' action\n",
> +				EAL_DEV_MP_ACTION_REQUEST);
> +			return ret;
> +		}
> +	}

<snip>

> +
> +#endif /* _HOTPLUG_MP_H_ */
> diff --git a/lib/librte_eal/common/include/rte_bus.h b/lib/librte_eal/common/include/rte_bus.h
> index eb9eded4e..720f7c3c8 100644
> --- a/lib/librte_eal/common/include/rte_bus.h
> +++ b/lib/librte_eal/common/include/rte_bus.h
> @@ -197,6 +197,9 @@ struct rte_bus_conf {
>   typedef enum rte_iova_mode (*rte_bus_get_iommu_class_t)(void);
>   
>   
> +/* Max length for a bus name */
> +#define RTE_BUS_NAME_MAX_LEN 32

Is this enforced anywhere in the bus codebase? Can we guarantee that bus 
name will never be bigger than this?

> +
>   /**
>    * A structure describing a generic bus.
>    */
> diff --git a/lib/librte_eal/common/include/rte_dev.h b/lib/librte_eal/common/include/rte_dev.h
> index 3879ff3ca..667df20f0 100644
> --- a/lib/librte_eal/common/include/rte_dev.h
> +++ b/lib/librte_eal/common/include/rte_dev.h
> @@ -152,6 +152,9 @@ struct rte_driver {
>    */
>   #define RTE_DEV_NAME_MAX_LEN 64
>   
> +/* Max devargs length be allowed */
> +#define RTE_DEV_ARGS_MAX_LEN 128

Same - is this enforced anywhere in the codebase related to devargs?

-- 
Thanks,
Anatoly