virtio: struct device - replace bus_id with dev_name(), dev_set_name() - Kernel

This is a discussion on virtio: struct device - replace bus_id with dev_name(), dev_set_name() - Kernel ; This patch is part of a larger patch series which will remove the "char bus_id[20]" name string from struct device. The device name is managed in the kobject anyway, and without any size limitation, and just needlessly copied into "struct ...

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Thread: virtio: struct device - replace bus_id with dev_name(), dev_set_name()

  1. virtio: struct device - replace bus_id with dev_name(), dev_set_name()

    This patch is part of a larger patch series which will remove
    the "char bus_id[20]" name string from struct device. The device
    name is managed in the kobject anyway, and without any size
    limitation, and just needlessly copied into "struct device".

    To set and read the device name dev_name(dev) and dev_set_name(dev)
    must be used. If your code uses static kobjects, which it shouldn't
    do, "const char *init_name" can be used to statically provide the
    name the registered device should have. At registration time, the
    init_name field is cleared, to enforce the use of dev_name(dev) to
    access the device name at a later time.

    We need to get rid of all occurrences of bus_id in the entire tree
    to be able to enable the new interface. Please apply this patch,
    and possibly convert any remaining remaining occurrences of bus_id.

    We want to submit a patch to -next, which will remove bus_id from
    "struct device", to find the remaining pieces to convert, and finally
    switch over to the new api, which will remove the 20 bytes array
    and does no longer have a size limitation.

    Thanks,
    Kay


    From: Kay Sievers
    Subject: virtio: struct device - replace bus_id with dev_name(), dev_set_name()

    CC: Rusty Russell
    Acked-by: Greg Kroah-Hartman
    Signed-Off-By: Kay Sievers
    ---


    diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
    index 5b78fd0..018c070 100644
    --- a/drivers/virtio/virtio.c
    +++ b/drivers/virtio/virtio.c
    @@ -176,7 +176,7 @@ int register_virtio_device(struct virtio_device *dev)

    /* Assign a unique device index and hence name. */
    dev->index = dev_index++;
    - sprintf(dev->dev.bus_id, "virtio%u", dev->index);
    + dev_set_name(&dev->dev, "virtio%u", dev->index);

    /* We always start by resetting the device, in case a previous
    * driver messed it up. This also tests that code path a little. */
    diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
    index c7dc37c..fbdd219 100644
    --- a/drivers/virtio/virtio_pci.c
    +++ b/drivers/virtio/virtio_pci.c
    @@ -75,7 +75,7 @@ MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
    * would make more sense for virtio to not insist on having it's own device. */
    static struct device virtio_pci_root = {
    .parent = NULL,
    - .bus_id = "virtio-pci",
    + .init_name = "virtio-pci",
    };

    /* Convert a generic virtio device to our structure */
    @@ -357,7 +357,7 @@ static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,

    /* register a handler for the queue with the PCI device's interrupt */
    err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
    - vp_dev->vdev.dev.bus_id, vp_dev);
    + dev_name(&vp_dev->vdev.dev), vp_dev);
    if (err)
    goto out_set_drvdata;


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  2. Re: virtio: struct device - replace bus_id with dev_name(), dev_set_name()

    On Friday 31 October 2008 06:10:22 Kay Sievers wrote:
    > This patch is part of a larger patch series which will remove
    > the "char bus_id[20]" name string from struct device. The device
    > name is managed in the kobject anyway, and without any size
    > limitation, and just needlessly copied into "struct device".


    OK, I've applied this patch.

    I'm curious how you're going to handle out-of-memory conditions?

    Thanks,
    Rusty.
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  3. Re: virtio: struct device - replace bus_id with dev_name(), dev_set_name()

    On Thu, Nov 6, 2008 at 04:45, Rusty Russell wrote:
    > On Friday 31 October 2008 06:10:22 Kay Sievers wrote:
    >> This patch is part of a larger patch series which will remove
    >> the "char bus_id[20]" name string from struct device. The device
    >> name is managed in the kobject anyway, and without any size
    >> limitation, and just needlessly copied into "struct device".

    >
    > OK, I've applied this patch.


    Thanks!

    > I'm curious how you're going to handle out-of-memory conditions?


    If the name can't be set, the following call to device_register() will
    fail, and should be handled by the caller. Just like today when we
    allocate the kobject name in device_register(). After the core has
    switched over, the name allocation will only happen a few lines
    earlier, it should not behave different otherwise. Is that what you
    mean?

    Thanks,
    Kay
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  4. Re: virtio: struct device - replace bus_id with dev_name(), dev_set_name()

    On Thursday 06 November 2008 17:28:56 Kay Sievers wrote:
    > On Thu, Nov 6, 2008 at 04:45, Rusty Russell wrote:
    > > I'm curious how you're going to handle out-of-memory conditions?

    >
    > If the name can't be set, the following call to device_register() will
    > fail, and should be handled by the caller. Just like today when we
    > allocate the kobject name in device_register(). After the core has
    > switched over, the name allocation will only happen a few lines
    > earlier, it should not behave different otherwise. Is that what you
    > mean?


    Yep, thanks. Sounds fine.

    Rusty.
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