Re: bonding sysfs output

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 25 Nov 2007 16:12:57 +0100 Wagner Ferenc <wferi@niif.hu> wrote:

> Hi,
> 
> Am I totally of the limit with the attached patch against
> drivers/net/bonding/bond_sysfs.c?  I'd like to receive some comments,
> as I'm not a kernel developer.

Plese alwayts cc netdev@vger.kernel.org on networking-related matters.

> I propose it as a fix for trailing NULs and spaces like eg.
> 
> $ od -c /sys/class/net/bond0/bonding/slaves 
> 0000000   e   t   h   -   l   e   f   t       e   t   h   -   r   i   g
> 0000020   h   t      \n  \0
> 0000025
> 
> I'm afraid there're other problems with "++more++" handling, but let's
> not consider those just yet.  Find the patch attached.  The first
> hunks also renames buffer to buf, for consistency's shake.
> 
> The original version had varying behaviour for Not Applicable cases.
> This patch also settles for empty files (not even a line feed) in
> those cases, but I'm not sure about the general policy on this matter.
> 

hm, there are a lot of changes there.  Were they all actually needed to fix
the one bug which you have described?


--- bond_sysfs.c.orig	2007-11-16 19:14:27.000000000 +0100
+++ bond_sysfs.c	2007-11-25 16:01:23.092973099 +0100
@@ -74,7 +74,7 @@
  * "show" function for the bond_masters attribute.
  * The class parameter is ignored.
  */
-static ssize_t bonding_show_bonds(struct class *cls, char *buffer)
+static ssize_t bonding_show_bonds(struct class *cls, char *buf)
 {
 	int res = 0;
 	struct bonding *bond;
@@ -86,14 +86,13 @@
 			/* not enough space for another interface name */
 			if ((PAGE_SIZE - res) > 10)
 				res = PAGE_SIZE - 10;
-			res += sprintf(buffer + res, "++more++");
+			res += sprintf(buf + res, "++more++ ");
 			break;
 		}
-		res += sprintf(buffer + res, "%s ",
+		res += sprintf(buf + res, "%s ",
 			       bond->dev->name);
 	}
-	res += sprintf(buffer + res, "\n");
-	res++;
+	if (res) buf[res-1] = '\n'; /* eat the leftover space */
 	up_read(&(bonding_rwsem));
 	return res;
 }
@@ -237,14 +236,13 @@
 			/* not enough space for another interface name */
 			if ((PAGE_SIZE - res) > 10)
 				res = PAGE_SIZE - 10;
-			res += sprintf(buf + res, "++more++");
+			res += sprintf(buf + res, "++more++ ");
 			break;
 		}
 		res += sprintf(buf + res, "%s ", slave->dev->name);
 	}
 	read_unlock_bh(&bond->lock);
-	res += sprintf(buf + res, "\n");
-	res++;
+	if (res) buf[res-1] = '\n'; /* eat the leftover space */
 	return res;
 }
 
@@ -401,7 +399,7 @@
 
 	return sprintf(buf, "%s %d\n",
 			bond_mode_tbl[bond->params.mode].modename,
-			bond->params.mode) + 1;
+			bond->params.mode);
 }
 
 static ssize_t bonding_store_mode(struct device *d,
@@ -452,17 +450,14 @@
 				      struct device_attribute *attr,
 				      char *buf)
 {
-	int count;
+	int count = 0;
 	struct bonding *bond = to_bond(d);
 
-	if ((bond->params.mode != BOND_MODE_XOR) &&
-	    (bond->params.mode != BOND_MODE_8023AD)) {
-		// Not Applicable
-		count = sprintf(buf, "NA\n") + 1;
-	} else {
+	if ((bond->params.mode == BOND_MODE_XOR) ||
+	    (bond->params.mode == BOND_MODE_8023AD)) {
 		count = sprintf(buf, "%s %d\n",
 			xmit_hashtype_tbl[bond->params.xmit_policy].modename,
-			bond->params.xmit_policy) + 1;
+			bond->params.xmit_policy);
 	}
 
 	return count;
@@ -522,7 +517,7 @@
 
 	return sprintf(buf, "%s %d\n",
 		       arp_validate_tbl[bond->params.arp_validate].modename,
-		       bond->params.arp_validate) + 1;
+		       bond->params.arp_validate);
 }
 
 static ssize_t bonding_store_arp_validate(struct device *d,
@@ -574,7 +569,7 @@
 {
 	struct bonding *bond = to_bond(d);
 
-	return sprintf(buf, "%d\n", bond->params.arp_interval) + 1;
+	return sprintf(buf, "%d\n", bond->params.arp_interval);
 }
 
 static ssize_t bonding_store_arp_interval(struct device *d,
@@ -671,10 +666,7 @@
 			res += sprintf(buf + res, "%u.%u.%u.%u ",
 			       NIPQUAD(bond->params.arp_targets[i]));
 	}
-	if (res)
-		res--;  /* eat the leftover space */
-	res += sprintf(buf + res, "\n");
-	res++;
+	if (res) buf[res-1] = '\n'; /* eat the leftover space */
 	return res;
 }
 
@@ -775,7 +767,7 @@
 {
 	struct bonding *bond = to_bond(d);
 
-	return sprintf(buf, "%d\n", bond->params.downdelay * bond->params.miimon) + 1;
+	return sprintf(buf, "%d\n", bond->params.downdelay * bond->params.miimon);
 }
 
 static ssize_t bonding_store_downdelay(struct device *d,
@@ -832,7 +824,7 @@
 {
 	struct bonding *bond = to_bond(d);
 
-	return sprintf(buf, "%d\n", bond->params.updelay * bond->params.miimon) + 1;
+	return sprintf(buf, "%d\n", bond->params.updelay * bond->params.miimon);
 
 }
 
@@ -896,7 +888,7 @@
 
 	return sprintf(buf, "%s %d\n",
 		bond_lacp_tbl[bond->params.lacp_fast].modename,
-		bond->params.lacp_fast) + 1;
+		bond->params.lacp_fast);
 }
 
 static ssize_t bonding_store_lacp(struct device *d,
@@ -952,7 +944,7 @@
 {
 	struct bonding *bond = to_bond(d);
 
-	return sprintf(buf, "%d\n", bond->params.miimon) + 1;
+	return sprintf(buf, "%d\n", bond->params.miimon);
 }
 
 static ssize_t bonding_store_miimon(struct device *d,
@@ -1053,9 +1045,7 @@
 	struct bonding *bond = to_bond(d);
 
 	if (bond->primary_slave)
-		count = sprintf(buf, "%s\n", bond->primary_slave->dev->name) + 1;
-	else
-		count = sprintf(buf, "\n") + 1;
+		count = sprintf(buf, "%s\n", bond->primary_slave->dev->name);
 
 	return count;
 }
@@ -1116,7 +1106,7 @@
 {
 	struct bonding *bond = to_bond(d);
 
-	return sprintf(buf, "%d\n", bond->params.use_carrier) + 1;
+	return sprintf(buf, "%d\n", bond->params.use_carrier);
 }
 
 static ssize_t bonding_store_carrier(struct device *d,
@@ -1158,7 +1148,7 @@
 {
 	struct slave *curr;
 	struct bonding *bond = to_bond(d);
-	int count;
+	int count = 0;
 
 
 	read_lock(&bond->curr_slave_lock);
@@ -1166,9 +1156,7 @@
 	read_unlock(&bond->curr_slave_lock);
 
 	if (USES_PRIMARY(bond->params.mode) && curr)
-		count = sprintf(buf, "%s\n", curr->dev->name) + 1;
-	else
-		count = sprintf(buf, "\n") + 1;
+		count = sprintf(buf, "%s\n", curr->dev->name);
 	return count;
 }
 
@@ -1259,7 +1247,7 @@
 	curr = bond->curr_active_slave;
 	read_unlock(&bond->curr_slave_lock);
 
-	return sprintf(buf, "%s\n", (curr) ? "up" : "down") + 1;
+	return sprintf(buf, "%s\n", (curr) ? "up" : "down");
 }
 static DEVICE_ATTR(mii_status, S_IRUGO, bonding_show_mii_status, NULL);
 
@@ -1276,10 +1264,8 @@
 
 	if (bond->params.mode == BOND_MODE_8023AD) {
 		struct ad_info ad_info;
-		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.aggregator_id) + 1;
+		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.aggregator_id);
 	}
-	else
-		count = sprintf(buf, "\n") + 1;
 
 	return count;
 }
@@ -1298,10 +1284,8 @@
 
 	if (bond->params.mode == BOND_MODE_8023AD) {
 		struct ad_info ad_info;
-		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0: ad_info.ports) + 1;
+		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0: ad_info.ports);
 	}
-	else
-		count = sprintf(buf, "\n") + 1;
 
 	return count;
 }
@@ -1320,10 +1304,8 @@
 
 	if (bond->params.mode == BOND_MODE_8023AD) {
 		struct ad_info ad_info;
-		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.actor_key) + 1;
+		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.actor_key);
 	}
-	else
-		count = sprintf(buf, "\n") + 1;
 
 	return count;
 }
@@ -1342,10 +1324,8 @@
 
 	if (bond->params.mode == BOND_MODE_8023AD) {
 		struct ad_info ad_info;
-		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.partner_key) + 1;
+		count = sprintf(buf, "%d\n", (bond_3ad_get_active_agg_info(bond, &ad_info)) ?  0 : ad_info.partner_key);
 	}
-	else
-		count = sprintf(buf, "\n") + 1;
 
 	return count;
 }
@@ -1371,11 +1351,9 @@
 				       ad_info.partner_system[2],
 				       ad_info.partner_system[3],
 				       ad_info.partner_system[4],
-				       ad_info.partner_system[5]) + 1;
+				       ad_info.partner_system[5]);
 		}
 	}
-	else
-		count = sprintf(buf, "\n") + 1;
 
 	return count;
 }