can: Speed up CAN frame receiption by using ml_priv

this patch removes the hlist that contains the CAN receiver filter lists.
It uses the 'midlayer private' pointer ml_priv and links the filters directly
to the CAN netdevice, which allows to omit the walk through the complete CAN
devices hlist for each received CAN frame.

This patch is tested and does not remove any locking.

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 61 insertions, 32 deletions

diff --git a/net/can/proc.c b/net/can/proc.c
index 9b9ad29be56..f4265cc9c3f 100644
--- a/net/can/proc.c
+++ b/net/can/proc.c
@@ -45,6 +45,7 @@
 #include <linux/proc_fs.h>
 #include <linux/list.h>
 #include <linux/rcupdate.h>
+#include <linux/if_arp.h>
 #include <linux/can/core.h>
 
 #include "af_can.h"
@@ -84,6 +85,9 @@ static const char rx_list_name[][8] = {
 	[RX_EFF] = "rx_eff",
 };
 
+/* receive filters subscribed for 'all' CAN devices */
+extern struct dev_rcv_lists can_rx_alldev_list;
+
 /*
  * af_can statistics stuff
  */
@@ -190,10 +194,6 @@ void can_stat_update(unsigned long data)
 
 /*
  * proc read functions
- *
- * From known use-cases we expect about 10 entries in a receive list to be
- * printed in the proc_fs. So PAGE_SIZE is definitely enough space here.
- *
  */
 
 static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
@@ -202,7 +202,6 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
 	struct receiver *r;
 	struct hlist_node *n;
 
-	rcu_read_lock();
 	hlist_for_each_entry_rcu(r, n, rx_list, list) {
 		char *fmt = (r->can_id & CAN_EFF_FLAG)?
 			"   %-5s  %08X  %08x  %08x  %08x  %8ld  %s\n" :
@@ -212,7 +211,6 @@ static void can_print_rcvlist(struct seq_file *m, struct hlist_head *rx_list,
 				(unsigned long)r->func, (unsigned long)r->data,
 				r->matches, r->ident);
 	}
-	rcu_read_unlock();
 }
 
 static void can_print_recv_banner(struct seq_file *m)
@@ -346,24 +344,39 @@ static const struct file_operations can_version_proc_fops = {
 	.release	= single_release,
 };
 
+static inline void can_rcvlist_proc_show_one(struct seq_file *m, int idx,
+					     struct net_device *dev,
+					     struct dev_rcv_lists *d)
+{
+	if (!hlist_empty(&d->rx[idx])) {
+		can_print_recv_banner(m);
+		can_print_rcvlist(m, &d->rx[idx], dev);
+	} else
+		seq_printf(m, "  (%s: no entry)\n", DNAME(dev));
+
+}
+
 static int can_rcvlist_proc_show(struct seq_file *m, void *v)
 {
 	/* double cast to prevent GCC warning */
 	int idx = (int)(long)m->private;
+	struct net_device *dev;
 	struct dev_rcv_lists *d;
-	struct hlist_node *n;
 
 	seq_printf(m, "\nreceive list '%s':\n", rx_list_name[idx]);
 
 	rcu_read_lock();
-	hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
 
-		if (!hlist_empty(&d->rx[idx])) {
-			can_print_recv_banner(m);
-			can_print_rcvlist(m, &d->rx[idx], d->dev);
-		} else
-			seq_printf(m, "  (%s: no entry)\n", DNAME(d->dev));
+	/* receive list for 'all' CAN devices (dev == NULL) */
+	d = &can_rx_alldev_list;
+	can_rcvlist_proc_show_one(m, idx, NULL, d);
+
+	/* receive list for registered CAN devices */
+	for_each_netdev_rcu(&init_net, dev) {
+		if (dev->type == ARPHRD_CAN && dev->ml_priv)
+			can_rcvlist_proc_show_one(m, idx, dev, dev->ml_priv);
 	}
+
 	rcu_read_unlock();
 
 	seq_putc(m, '\n');
@@ -383,34 +396,50 @@ static const struct file_operations can_rcvlist_proc_fops = {
 	.release	= single_release,
 };
 
+static inline void can_rcvlist_sff_proc_show_one(struct seq_file *m,
+						 struct net_device *dev,
+						 struct dev_rcv_lists *d)
+{
+	int i;
+	int all_empty = 1;
+
+	/* check wether at least one list is non-empty */
+	for (i = 0; i < 0x800; i++)
+		if (!hlist_empty(&d->rx_sff[i])) {
+			all_empty = 0;
+			break;
+		}
+
+	if (!all_empty) {
+		can_print_recv_banner(m);
+		for (i = 0; i < 0x800; i++) {
+			if (!hlist_empty(&d->rx_sff[i]))
+				can_print_rcvlist(m, &d->rx_sff[i], dev);
+		}
+	} else
+		seq_printf(m, "  (%s: no entry)\n", DNAME(dev));
+}
+
 static int can_rcvlist_sff_proc_show(struct seq_file *m, void *v)
 {
+	struct net_device *dev;
 	struct dev_rcv_lists *d;
-	struct hlist_node *n;
 
 	/* RX_SFF */
 	seq_puts(m, "\nreceive list 'rx_sff':\n");
 
 	rcu_read_lock();
-	hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
-		int i, all_empty = 1;
-		/* check wether at least one list is non-empty */
-		for (i = 0; i < 0x800; i++)
-			if (!hlist_empty(&d->rx_sff[i])) {
-				all_empty = 0;
-				break;
-			}
-
-		if (!all_empty) {
-			can_print_recv_banner(m);
-			for (i = 0; i < 0x800; i++) {
-				if (!hlist_empty(&d->rx_sff[i]))
-					can_print_rcvlist(m, &d->rx_sff[i],
-							  d->dev);
-			}
-		} else
-			seq_printf(m, "  (%s: no entry)\n", DNAME(d->dev));
+
+	/* sff receive list for 'all' CAN devices (dev == NULL) */
+	d = &can_rx_alldev_list;
+	can_rcvlist_sff_proc_show_one(m, NULL, d);
+
+	/* sff receive list for registered CAN devices */
+	for_each_netdev_rcu(&init_net, dev) {
+		if (dev->type == ARPHRD_CAN && dev->ml_priv)
+			can_rcvlist_sff_proc_show_one(m, dev, dev->ml_priv);
 	}
+
 	rcu_read_unlock();
 
 	seq_putc(m, '\n');