Re: udev - Shouldn't we blacklist some devices?

[Greg KH <greg@kroah.com>]

On Sun, Jan 04, 2004 at 12:07:21AM +0100, Kay Sievers wrote:
> On Sat, Jan 03, 2004 at 01:48:57PM -0800, Greg KH wrote:
> > On Sat, Jan 03, 2004 at 09:07:53PM +0100, Kay Sievers wrote:
> > > While connecting my flash reader to the USB bus I get:
> > > 
> > > Jan  3 20:56:58 pim udev[31673]: sleep_for_dev: looking for '/sys/class/scsi_device/54:0:0:2/dev'
> > > Jan  3 20:56:59 pim udev[31695]: sleep_for_dev: looking for '/sys/class/scsi_device/54:0:0:3/dev'
> > > Jan  3 20:56:59 pim udev[31514]: sleep_for_dev: looking for '/sys/class/scsi_host/host54/dev'
> > > 
> > > Shouldn't we blacklist devices like  /sys/class/scsi_device/*, /sys/class/scsi_host/* ?
> > 
> > Yes we should, as we try to remove those device nodes when the devices
> > get removed (look for the 'trying to remove host54' messages), which
> > could be very dangerous.
> > 
> 
> So, here we go:
> 
> Blacklist devices that we don't want to process, like:
> /sys/class/scsi_device/*, /sys/class/scsi_host/*,
> cause these devices are handled by the block device events we receive
> and we don't try to remove non existing nodes.

How about this patch instead (not tested)?  It removes the explicit test
for net class devices.

thanks,

greg k-h


=== udev.c 1.27 vs edited ==--- 1.27/udev.c	Tue Dec 30 16:33:12 2003
+++ edited/udev.c	Sat Jan  3 15:29:00 2004
@@ -139,12 +139,20 @@
 	return retval;
 }
 
+static char *subsystem_blacklist[] = {
+	"net",
+	"scsi_host",
+	"scsi_device",
+	"",
+};
+
 static inline int udev_hotplug(int argc, char **argv)
 {
 	char *action;
 	char *devpath;
 	char *subsystem;
 	int retval = -EINVAL;
+	int i;
 
 	subsystem = argv[1];
 
@@ -162,10 +170,14 @@
 		goto exit;
 	}
 
-	/* but we don't care about net class devices */
-	if (strcmp(subsystem, "net") = 0) {
-		dbg("don't care about net devices");
-		goto exit;
+	/* skip blacklisted subsystems */
+	i = 0;
+	while (subsystem_blacklist[i][0] != '\0') {
+		if (strcmp(subsystem, subsystem_blacklist[i])) {
+			dbg("don't care about '%s' devices", subsystem);
+			goto exit;
+		}
+		i++;
 	}
 
 	action = get_action();


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