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

[Haiyang Zhang <haiyangz@microsoft.com>]

> -----Original Message-----
> From: Andrew Lunn <andrew@lunn.ch>
> Sent: Monday, April 12, 2021 8:32 AM
> To: Dexuan Cui <decui@microsoft.com>
> Cc: davem@davemloft.net; kuba@kernel.org; KY Srinivasan
> <kys@microsoft.com>; Haiyang Zhang <haiyangz@microsoft.com>; Stephen
> Hemminger <sthemmin@microsoft.com>; wei.liu@kernel.org; Wei Liu
> <liuwe@microsoft.com>; netdev@vger.kernel.org; leon@kernel.org;
> bernd@petrovitsch.priv.at; rdunlap@infradead.org; Shachar Raindel
> <shacharr@microsoft.com>; linux-kernel@vger.kernel.org; linux-
> hyperv@vger.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?
We don't have hot{un}plug of CPU feature yet.

> 
> > +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?
For protocol version mismatch, the host and guest will either negotiate the 
highest common version, or fail to probe. So this kind of warnings are not 
expected.

> 
> > +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.
Will do.

Thanks,
- Haiyang