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    SubjectRe: [PATCH] fix error handling in bus_add_device
    Greg KH wrote:
    > On Wed, May 18, 2005 at 09:19:37AM +0200, Hannes Reinecke wrote:
    >>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.
    > Ok, I agree that we should have error checks in there. Now, could you
    > make your patch against the latest -mm tree instead due to all of the
    > changes involved in that area in my trees? That way I can apply it :)
    Whee, innovations.
    Which your patches to -mm the whole thing is even easier and now
    actually looks quite sane.
    New patch attached.


    Dr. Hannes Reinecke
    SuSE Linux AG S390 & zSeries
    Maxfeldstraße 5 +49 911 74053 688
    90409 Nürnberg
    From: Hannes Reinecke <>
    Subject: Fix error handling in bus_add_device()

    The error handling in bus_add_device() and device_attach() is simply
    non-existing. This patch propagates any error from device_attach to
    the upper layers to allow for a proper recovery.

    --- linux-2.6.12-rc4-mm2/drivers/base/bus.c.orig 2005-05-18 10:26:50.000000000 +0200
    +++ linux-2.6.12-rc4-mm2/drivers/base/bus.c 2005-05-18 10:36:08.000000000 +0200
    @@ -270,11 +270,14 @@ int bus_add_device(struct device * dev)

    if (bus) {
    pr_debug("bus %s: add device %s\n", bus->name, dev->bus_id);
    - device_attach(dev);
    + error = device_attach(dev);
    klist_add_tail(&bus->klist_devices, &dev->knode_bus);
    - 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 >= 0)
    + 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");
    + }
    return error;
    @@ -394,7 +397,7 @@ static int bus_rescan_devices_helper(str
    int *count = data;

    - if (!dev->driver && device_attach(dev))
    + if (!dev->driver && (device_attach(dev) > 0))

    return 0;
    --- linux-2.6.12-rc4-mm2/drivers/base/dd.c.orig 2005-05-18 10:29:27.000000000 +0200
    +++ linux-2.6.12-rc4-mm2/drivers/base/dd.c 2005-05-18 10:39:45.000000000 +0200
    @@ -119,7 +119,8 @@ static int __device_attach(struct device
    * driver_probe_device() for each pair. If a compatible
    * pair is found, break out and return.
    - * Returns 1 if the device was bound to a driver; 0 otherwise.
    + * Returns 1 if the device was bound to a driver;
    + * 0 if no matching device was found; error code otherwise.
    int device_attach(struct device * dev)
     \ /
      Last update: 2005-05-18 10:47    [W:0.034 / U:9.524 seconds]
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