RE: [PATCH 1/1] Drivers: infiniband: hw: vmbus-nd: NetworkDirect driver for Linux

-----Original Message-----
From: Greg KH [mailto:gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org]
Sent: Wednesday, July 27, 2016 2:26 PM
To: KY Srinivasan <redacted>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devel-tBiZLqfeLfOHmIFyCCdPziST3g8Odh+X@public.gmane.org; linux-
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dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; olaf-QOLJcTWqO2uzQB+pC5nmwQ@public.gmane.org; apw-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org;
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leann.ogasawara-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org; Long Li [off-list ref]
Subject: Re: [PATCH 1/1] Drivers: infiniband: hw: vmbus-nd: NetworkDirect
driver for Linux

On Wed, Jul 27, 2016 at 09:09:08PM +0000, KY Srinivasan wrote:

quoted

quoted

-----Original Message-----
From: Greg KH [mailto:gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org]
Sent: Tuesday, July 26, 2016 9:41 PM
To: KY Srinivasan <redacted>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; devel-tBiZLqfeLfOHmIFyCCdPziST3g8Odh+X@public.gmane.org; linux-
rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org; sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org;
dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; olaf-QOLJcTWqO2uzQB+pC5nmwQ@public.gmane.org; apw-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org;
vkuznets-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; jasowang-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org;
leann.ogasawara-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org; Long Li [off-list ref]
Subject: Re: [PATCH 1/1] Drivers: infiniband: hw: vmbus-nd: NetworkDirect
driver for Linux

On Tue, Jul 26, 2016 at 07:05:37PM -0700, kys-Lp/cVzEoVyZiJJESP9tAQJZ3qXmFLfmx@public.gmane.org
wrote:

quoted

+/*
+ * Create a char device that can support read/write for passing
+ * the payload.
+ */

That sounds "interesting"...

quoted

+
+static struct completion ip_event;
+static bool opened;
+
+char hvnd_ip_addr[4];
+char hvnd_mac_addr[6];
+bool hvnd_addr_set;

Global variables?

quoted

quoted

+
+int hvnd_get_ip_addr(char **ip_addr, char **mac_addr)
+{
+	int t;
+
+	/*
+	 * Now wait for the user level daemon to get us the
+	 * IP addresses bound to the MAC address.
+	 */
+	if (!hvnd_addr_set) {
+		t = wait_for_completion_timeout(&ip_event, 600*HZ);
+		if (t == 0)
+			return -ETIMEDOUT;
+	}
+
+	if (hvnd_addr_set) {
+		*ip_addr = hvnd_ip_addr;
+		*mac_addr = hvnd_mac_addr;
+		return 0;
+	}
+
+	return -ENODATA;
+}
+
+static ssize_t hvnd_write(struct file *file, const char __user *buf,
+			size_t count, loff_t *ppos)
+{
+	char input[120];
+	int scaned, i;
+	unsigned int mac_addr[6], ip_addr[4];
+
+	if (hvnd_addr_set) {
+		hvnd_error("IP/MAC address already set, ignoring input\n");
+		return count;
+	}
+
+	if (count > sizeof(input)-1)
+		return -EINVAL;
+
+	if (copy_from_user(input, buf, count))
+		return -EFAULT;
+
+	input[count] = 0;
+
+	/*
+	 * Wakeup the context that may be waiting for this.
+	 */
+	hvnd_debug("get user mode input: %s\n", input);
+
+	scaned = sscanf(input,
+		"rdmaMacAddress=\"%x:%x:%x:%x:%x:%x\"

rdmaIPv4Address=\"%u.%u.%u.%u\"",

quoted

+		&mac_addr[0],
+		&mac_addr[1],
+		&mac_addr[2],
+		&mac_addr[3],
+		&mac_addr[4],
+		&mac_addr[5],
+		&ip_addr[0],
+		&ip_addr[1],
+		&ip_addr[2],
+		&ip_addr[3]);

Oh, that's a mess, you are going to parse text in the kernel that is
passed on a char device?  Please tell me that not all IB drivers are
like this...

Greg,

This driver is plugging into the Windows NetworkDirect infrastructure on the

host side.

quoted

The fabric assigns the MAC/IP address for the interface. I have chosen this

mechanism for

quoted

passing the information to the kernel driver. I can certainly look at other

mechanism.

Why create a new mechanism that is different from all other IB
controllers?  Shouldn't this just be a "normal" network device in that
manner?

That is a good point. I will look at other options.

Regards,

K. Y
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