Re: Problems with setting devices' bus_id on sparc32

[David Miller <davem@davemloft.net>]

From: Jurij Smakov <jurij@wooyd.org>
Date: Thu, 26 Oct 2006 23:55:03 -0700

> While investigating Debian bug #394697 [0] on sparc32, I've found that 
> in a couple of places the bus_id field of struct device is set by 
> copying the dp->path_component_name (obtained from prom) without any 
> length checking. In most cases it happens to work, however on 
> SparcStation5 for some devices this string is over 20 chars long (like 
> 'power-management@4,a0000000'), and that exceeds the amount of memory 
> allocated for bus_id (which is BUS_ID_SIZE = 20). So, blindly 
> copying the names into bus_id using strcpy() leads to all kinds of bad 
> things. The attached hackish patch replaces strcpy() by strlcpy() in 
> two places, making it possible to boot SS5 again (tested in QEMU, 
> where vanilla 2.6.18 fails to boot with symptoms identical to the ones
> described in the bug).
> 
> [0] http://bugs.debian.org/394697

I happened to be playing around in this area recently.

I recently fixed the problem on sparc64 that the bus_id's being
generated by of_device.c were not globally unique (the device layer
requires that they are), so I changed it to "%s@%08x" using dp->name
and dp->node.

But that will run into the same length issue.

So let's just use "%08x" and dp->node, with option fixed sized string
prefix for ebus/isa/sbus, for all of these things.

diff --git a/arch/sparc/kernel/ebus.c b/arch/sparc/kernel/ebus.c
index 75ac24d..8ed9dcb 100644
--- a/arch/sparc/kernel/ebus.c
+++ b/arch/sparc/kernel/ebus.c
@@ -237,12 +237,12 @@ void __init fill_ebus_device(struct devi
 	dev->ofdev.node = dp;
 	dev->ofdev.dev.parent = &dev->bus->ofdev.dev;
 	dev->ofdev.dev.bus = &ebus_bus_type;
-	strcpy(dev->ofdev.dev.bus_id, dp->path_component_name);
+	sprintf(dev->ofdev.dev.bus_id, "ebus[%08x]", dp->node);
 
 	/* Register with core */
 	if (of_device_register(&dev->ofdev) != 0)
 		printk(KERN_DEBUG "ebus: device registration error for %s!\n",
-		       dev->ofdev.dev.bus_id);
+		       dp->path_component_name);
 
 	if ((dp = dp->child) != NULL) {
 		dev->children = (struct linux_ebus_child *)
diff --git a/arch/sparc/kernel/of_device.c b/arch/sparc/kernel/of_device.c
index 74bef2a..46200c4 100644
--- a/arch/sparc/kernel/of_device.c
+++ b/arch/sparc/kernel/of_device.c
@@ -651,7 +651,7 @@ build_resources:
 	if (!parent)
 		strcpy(op->dev.bus_id, "root");
 	else
-		strcpy(op->dev.bus_id, dp->path_component_name);
+		sprintf(op->dev.bus_id, "%08x", dp->node);
 
 	if (of_device_register(op)) {
 		printk("%s: Could not register of device.\n",
diff --git a/arch/sparc64/kernel/ebus.c b/arch/sparc64/kernel/ebus.c
index 2df25c2..9b6fdbc 100644
--- a/arch/sparc64/kernel/ebus.c
+++ b/arch/sparc64/kernel/ebus.c
@@ -389,12 +389,12 @@ static void __init fill_ebus_device(stru
 	dev->ofdev.node = dp;
 	dev->ofdev.dev.parent = &dev->bus->ofdev.dev;
 	dev->ofdev.dev.bus = &ebus_bus_type;
-	strcpy(dev->ofdev.dev.bus_id, dp->path_component_name);
+	sprintf(dev->ofdev.dev.bus_id, "ebus[%08x]", dp->node);
 
 	/* Register with core */
 	if (of_device_register(&dev->ofdev) != 0)
 		printk(KERN_DEBUG "ebus: device registration error for %s!\n",
-		       dev->ofdev.dev.bus_id);
+		       dp->path_component_name);
 
 	dp = dp->child;
 	if (dp) {
diff --git a/arch/sparc64/kernel/isa.c b/arch/sparc64/kernel/isa.c
index 0f3aec7..cc56413 100644
--- a/arch/sparc64/kernel/isa.c
+++ b/arch/sparc64/kernel/isa.c
@@ -115,12 +115,12 @@ static void __init isa_fill_devices(stru
 		isa_dev->ofdev.node = dp;
 		isa_dev->ofdev.dev.parent = &isa_br->ofdev.dev;
 		isa_dev->ofdev.dev.bus = &isa_bus_type;
-		strcpy(isa_dev->ofdev.dev.bus_id, dp->path_component_name);
+		sprintf(isa_dev->ofdev.dev.bus_id, "isa[%08x]", dp->node);
 
 		/* Register with core */
 		if (of_device_register(&isa_dev->ofdev) != 0) {
 			printk(KERN_DEBUG "isa: device registration error for %s!\n",
-			       isa_dev->ofdev.dev.bus_id);
+			       dp->path_component_name);
 			kfree(isa_dev);
 			goto next_sibling;
 		}
diff --git a/arch/sparc64/kernel/of_device.c b/arch/sparc64/kernel/of_device.c
index 983ca5f..8cc14fc 100644
--- a/arch/sparc64/kernel/of_device.c
+++ b/arch/sparc64/kernel/of_device.c
@@ -861,7 +861,7 @@ static struct of_device * __init scan_on
 	if (!parent)
 		strcpy(op->dev.bus_id, "root");
 	else
-		sprintf(op->dev.bus_id, "%s@%08x", dp->name, dp->node);
+		sprintf(op->dev.bus_id, "%08x", dp->node);
 
 	if (of_device_register(op)) {
 		printk("%s: Could not register of device.\n",
diff --git a/drivers/sbus/sbus.c b/drivers/sbus/sbus.c
index 935952e..98fcbb3 100644
--- a/drivers/sbus/sbus.c
+++ b/drivers/sbus/sbus.c
@@ -61,11 +61,11 @@ static void __init fill_sbus_device(stru
 	else
 		sdev->ofdev.dev.parent = &sdev->bus->ofdev.dev;
 	sdev->ofdev.dev.bus = &sbus_bus_type;
-	strcpy(sdev->ofdev.dev.bus_id, dp->path_component_name);
+	sprintf(sdev->ofdev.dev.bus_id, "sbus[%08x]", dp->node);
 
 	if (of_device_register(&sdev->ofdev) != 0)
 		printk(KERN_DEBUG "sbus: device registration error for %s!\n",
-		       sdev->ofdev.dev.bus_id);
+		       dp->path_component_name);
 }
 
 static void __init sbus_bus_ranges_init(struct device_node *dp, struct sbus_bus *sbus)