netdev - Re: [PATCH v4 net-next] net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)

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Date:   Mon, 12 Apr 2021 14:32:00 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Dexuan Cui <decui@...rosoft.com>
Cc:     davem@...emloft.net, kuba@...nel.org, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        liuwe@...rosoft.com, netdev@...r.kernel.org, leon@...nel.org,
        bernd@...rovitsch.priv.at, rdunlap@...radead.org,
        shacharr@...rosoft.com, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org
Subject: Re: [PATCH v4 net-next] net: mana: Add a driver for Microsoft Azure
 Network Adapter (MANA)

> +static void mana_gd_deregiser_irq(struct gdma_queue *queue)
> +{
> +	struct gdma_dev *gd = queue->gdma_dev;
> +	struct gdma_irq_context *gic;
> +	struct gdma_context *gc;
> +	struct gdma_resource *r;
> +	unsigned int msix_index;
> +	unsigned long flags;
> +
> +	/* At most num_online_cpus() + 1 interrupts are used. */
> +	msix_index = queue->eq.msix_index;
> +	if (WARN_ON(msix_index > num_online_cpus()))
> +		return;

Do you handle hot{un}plug of CPUs?

> +static void mana_hwc_init_event_handler(void *ctx, struct gdma_queue *q_self,
> +					struct gdma_event *event)
> +{
> +	struct hw_channel_context *hwc = ctx;
> +	struct gdma_dev *gd = hwc->gdma_dev;
> +	union hwc_init_type_data type_data;
> +	union hwc_init_eq_id_db eq_db;
> +	u32 type, val;
> +
> +	switch (event->type) {
> +	case GDMA_EQE_HWC_INIT_EQ_ID_DB:
> +		eq_db.as_uint32 = event->details[0];
> +		hwc->cq->gdma_eq->id = eq_db.eq_id;
> +		gd->doorbell = eq_db.doorbell;
> +		break;
> +
> +	case GDMA_EQE_HWC_INIT_DATA:
> +
> +		type_data.as_uint32 = event->details[0];
> +
> +	case GDMA_EQE_HWC_INIT_DONE:
> +		complete(&hwc->hwc_init_eqe_comp);
> +		break;

...

> +	default:
> +		WARN_ON(1);
> +		break;
> +	}

Are these events from the firmware? If you have newer firmware with an
older driver, are you going to spam the kernel log with WARN_ON dumps?

> +static int mana_move_wq_tail(struct gdma_queue *wq, u32 num_units)
> +{
> +	u32 used_space_old;
> +	u32 used_space_new;
> +
> +	used_space_old = wq->head - wq->tail;
> +	used_space_new = wq->head - (wq->tail + num_units);
> +
> +	if (used_space_new > used_space_old) {
> +		WARN_ON(1);
> +		return -ERANGE;
> +	}

You could replace the 1 by the condition. There are a couple of these.

    Andrew