Messages in this thread Patch in this message | | | Date | Wed, 18 May 2005 09:19:37 +0200 | From | Hannes Reinecke <> | Subject | Re: [PATCH] fix error handling in bus_add_device |
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Greg KH wrote: > On Thu, May 12, 2005 at 04:19:24PM +0200, Hannes Reinecke wrote: >>Hi Greg, >> >>this patch fixes the error handling in bus_add_device() and >>device_attach(). Previously it was 'interesting'. >>And totally confusing to boot. > > I agree, that's why it has been rewritten in the -mm tree :) > > Anyway, your patch doesn't take into account that device_attach()'s > return value is tested in the bus_rescan_devices_helper(), so if you > change the return value, that also needs to be changed. > > But even in the -mm tree, the bus_add_devices() function has not had the > error handling added to it that you provided, is there any devices that > you are seeing that need this? > Not yet :-)
I'm just doing some cleanups here which me and Kay Sievers will be exploiting in the near future. My main point is: either we do an error check in bus_add_device and return a proper status, or we don't and fix bus_add_device to be of type 'void'. And as some functions called by bus_add_device may fail I thought it reasonable to evaluate the return status properly. Unless you tell me that bus_add_device is a fire-and-forget procedure and we don't care at all for any failures. But then we should at least set the type of bus_add_device() to 'void'. You're the maintainer, you have to decide :-). I don't care either way, I just want to have it consistent.
But you're correct about the bus_rescan_devices_helper. Fixed and new patch attached.
Cheers,
Hannes -- Dr. Hannes Reinecke hare@suse.de SuSE Linux AG S390 & zSeries Maxfeldstraße 5 +49 911 74053 688 90409 Nürnberg http://www.suse.de From: Hannes Reinecke <hare@suse.de> Subject: Fix error handling in bus_add_device()
The error handling in bus_add_device() and device_attach() is simply non-existing. This patch updates both function to align with the default driver core convention to return '0' on success and an error code otherwise. Note that '-ENODEV' is not an error for device_attach and driver_probe_device as it is quite possible that no matching device was found.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
diff -pur linux-2.6.12-rc4.orig/drivers/base/bus.c linux-2.6.12-rc4/drivers/base/bus.c --- linux-2.6.12-rc4.orig/drivers/base/bus.c 2005-05-06 23:20:31.000000000 -0600 +++ linux-2.6.12-rc4/drivers/base/bus.c 2005-05-12 08:05:02.000000000 -0600 @@ -312,11 +312,11 @@ int device_attach(struct device * dev) { struct bus_type * bus = dev->bus; struct list_head * entry; - int error; + int error = -ENODEV; if (dev->driver) { device_bind_driver(dev); - return 1; + return 0; } if (bus->match) { @@ -325,7 +325,7 @@ int device_attach(struct device * dev) error = driver_probe_device(drv, dev); if (!error) /* success, driver matched */ - return 1; + return 0; if (error != -ENODEV && error != -ENXIO) /* driver matched but the probe failed */ printk(KERN_WARNING @@ -334,7 +334,7 @@ int device_attach(struct device * dev) } } - return 0; + return error; } @@ -460,11 +460,17 @@ int bus_add_device(struct device * dev) down_write(&dev->bus->subsys.rwsem); pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id); list_add_tail(&dev->bus_list, &dev->bus->devices.list); - device_attach(dev); + error = device_attach(dev); up_write(&dev->bus->subsys.rwsem); - device_add_attrs(bus, dev); - sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id); - sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus"); + if (!error || error == -ENODEV) + error = device_add_attrs(bus, dev); + if (!error) { + sysfs_create_link(&bus->devices.kobj, &dev->kobj, dev->bus_id); + sysfs_create_link(&dev->kobj, &dev->bus->subsys.kset.kobj, "bus"); + } else { + pr_debug("bus %s: attach device %s failed with %d\n", bus->name, dev->bus_id, error); + put_bus(bus); + } } return error; } @@ -588,7 +594,7 @@ static int bus_rescan_devices_helper(str { int *count = data; - if (!dev->driver && device_attach(dev)) + if (!dev->driver && !device_attach(dev)) (*count)++; return 0; | |