xen-netback: (re-)create a debugfs node for hash information

It is useful to be able to see the hash configuration when running tests.
This patch adds a debugfs node for that purpose.

The original version of this patch (commit c0c64c152389) was reverted due
to build failures caused by a conflict with commit 0364a8824c02
("xen-netback: switch to threaded irq for control ring"). This new version
of the patch is nearly identical to the original, the only difference
being that creation of the debugfs node is predicated on 'ctrl_irq' being
non-zero rather then the now non-existent 'ctrl_task'.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David S. Miller <davem@davemloft.net>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/xen-netback/common.h

@@ -407,4 +407,8 @@ u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
 
 void xenvif_set_skb_hash(struct xenvif *vif, struct sk_buff *skb);
 
+#ifdef CONFIG_DEBUG_FS
+void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m);
+#endif
+
 #endif /* __XEN_NETBACK__COMMON_H__ */

drivers/net/xen-netback/hash.c

@@ -360,6 +360,74 @@ u32 xenvif_set_hash_mapping(struct xenvif *vif, u32 gref, u32 len,
 	return XEN_NETIF_CTRL_STATUS_SUCCESS;
 }
 
+#ifdef CONFIG_DEBUG_FS
+void xenvif_dump_hash_info(struct xenvif *vif, struct seq_file *m)
+{
+	unsigned int i;
+
+	switch (vif->hash.alg) {
+	case XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ:
+		seq_puts(m, "Hash Algorithm: TOEPLITZ\n");
+		break;
+
+	case XEN_NETIF_CTRL_HASH_ALGORITHM_NONE:
+		seq_puts(m, "Hash Algorithm: NONE\n");
+		/* FALLTHRU */
+	default:
+		return;
+	}
+
+	if (vif->hash.flags) {
+		seq_puts(m, "\nHash Flags:\n");
+
+		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4)
+			seq_puts(m, "- IPv4\n");
+		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP)
+			seq_puts(m, "- IPv4 + TCP\n");
+		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6)
+			seq_puts(m, "- IPv6\n");
+		if (vif->hash.flags & XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP)
+			seq_puts(m, "- IPv6 + TCP\n");
+	}
+
+	seq_puts(m, "\nHash Key:\n");
+
+	for (i = 0; i < XEN_NETBK_MAX_HASH_KEY_SIZE; ) {
+		unsigned int j, n;
+
+		n = 8;
+		if (i + n >= XEN_NETBK_MAX_HASH_KEY_SIZE)
+			n = XEN_NETBK_MAX_HASH_KEY_SIZE - i;
+
+		seq_printf(m, "[%2u - %2u]: ", i, i + n - 1);
+
+		for (j = 0; j < n; j++, i++)
+			seq_printf(m, "%02x ", vif->hash.key[i]);
+
+		seq_puts(m, "\n");
+	}
+
+	if (vif->hash.size != 0) {
+		seq_puts(m, "\nHash Mapping:\n");
+
+		for (i = 0; i < vif->hash.size; ) {
+			unsigned int j, n;
+
+			n = 8;
+			if (i + n >= vif->hash.size)
+				n = vif->hash.size - i;
+
+			seq_printf(m, "[%4u - %4u]: ", i, i + n - 1);
+
+			for (j = 0; j < n; j++, i++)
+				seq_printf(m, "%4u ", vif->hash.mapping[i]);
+
+			seq_puts(m, "\n");
+		}
+	}
+}
+#endif /* CONFIG_DEBUG_FS */
+
 void xenvif_init_hash(struct xenvif *vif)
 {
 	if (xenvif_hash_cache_size == 0)

drivers/net/xen-netback/xenbus.c

@@ -165,7 +165,7 @@ xenvif_write_io_ring(struct file *filp, const char __user *buf, size_t count,
 	return count;
 }
 
-static int xenvif_dump_open(struct inode *inode, struct file *filp)
+static int xenvif_io_ring_open(struct inode *inode, struct file *filp)
 {
 	int ret;
 	void *queue = NULL;
@@ -179,13 +179,35 @@ static int xenvif_dump_open(struct inode *inode, struct file *filp)
 
 static const struct file_operations xenvif_dbg_io_ring_ops_fops = {
 	.owner = THIS_MODULE,
-	.open = xenvif_dump_open,
+	.open = xenvif_io_ring_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
 	.release = single_release,
 	.write = xenvif_write_io_ring,
 };
 
+static int xenvif_read_ctrl(struct seq_file *m, void *v)
+{
+	struct xenvif *vif = m->private;
+
+	xenvif_dump_hash_info(vif, m);
+
+	return 0;
+}
+
+static int xenvif_ctrl_open(struct inode *inode, struct file *filp)
+{
+	return single_open(filp, xenvif_read_ctrl, inode->i_private);
+}
+
+static const struct file_operations xenvif_dbg_ctrl_ops_fops = {
+	.owner = THIS_MODULE,
+	.open = xenvif_ctrl_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
 static void xenvif_debugfs_addif(struct xenvif *vif)
 {
 	struct dentry *pfile;
@@ -210,6 +232,17 @@ static void xenvif_debugfs_addif(struct xenvif *vif)
 				pr_warn("Creation of io_ring file returned %ld!\n",
 					PTR_ERR(pfile));
 		}
+
+		if (vif->ctrl_irq) {
+			pfile = debugfs_create_file("ctrl",
+						    S_IRUSR,
+						    vif->xenvif_dbg_root,
+						    vif,
+						    &xenvif_dbg_ctrl_ops_fops);
+			if (IS_ERR_OR_NULL(pfile))
+				pr_warn("Creation of ctrl file returned %ld!\n",
+					PTR_ERR(pfile));
+		}
 	} else
 		netdev_warn(vif->dev,
 			    "Creation of vif debugfs dir returned %ld!\n",