Re: [PATCH 1/3] ib core: Make device counter infrastructure dynamic

[Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Tue, Mar 15, 2016 at 10:54:42AM -0500, Christoph Lameter wrote:
 
>+static ssize_t show_protocol_stats(struct ib_device *dev, int index,
>+				   u8 port, char *buf)
>+{
>+	struct rdma_protocol_stats stats = {0};
>+	ssize_t ret;
>+
>+	ret = dev->get_protocol_stats(dev, &stats, port);
>+	if (ret)
>+		return ret;
>+
>+	return sprintf(buf, "%llu\n", stats.value[index]);
>+}

This works fine when there are few counters, but if there are lots? What 
about changing things to include the index in the get_protocol_stats() call 
so that we just grab the single item we are looking for?

>+static struct attribute_group *create_protocol_stats(struct ib_device 
>*device,
>+						     struct kobject *kobj,
>+						     u8 port) {
>+	struct attribute_group *ag;
>+	struct rdma_protocol_stats stats = {0};
>+	u32 counters;
>+	u32 i;
>+	int ret;
>+
>+	ret = device->get_protocol_stats(device, &stats, port);
>+
>+	if (ret || !stats.name)
>+		return NULL;
>+
>+	ag = kzalloc(sizeof(*ag), GFP_KERNEL);
>+	if (!ag)
>+		return NULL;
>+
>+	ag->name = stats.dirname;
>+
>+	for (counters = 0; stats.name[counters]; counters++)
>+		;
>+
>+	BUG_ON(counters > MAX_NR_PROTOCOL_STATS);

Should we really be bringing the machine crashing down here?

-Denny
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