2009/5/5 Ming Lei <tom.leiming@xxxxxxxxx>:
> On Mon, 4 May 2009 11:07:52 -0400 (EDT)
> Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
>
>> On Mon, 4 May 2009, Arjan van de Ven wrote:
>>
>> > > > for normal device probing we already have infrastructure
>> > > > though... wait_for_device_probe, driver_probe_done and
>> > > > friends... (the scsi scanning thread is being converted to the
>> > > > async infrastructure btw)
>> > > >
>> > > > do we need to invent more ?
>> > >
>> > > I suppose the usb-storage scanning thread could also be converted
>> > > to the async infrastructure, although I haven't heard of anybody
>> > > working on it.
>> > >
>> > > But the USB hub driver's thread (khubd) cannot be converted. It
>> > > is central to the discovery of USB-based block devices. How
>> > > would you handle that?
>> >
>> > take a ref in the driver_probe_done() sense, and release it when you
>> > know you're done probing....
>> >
>> > at that point all existing infrastructure will just work.
>>
>> Isn't there still something missing? The wait_for_device_probe()
>> routine would wait until all attached devices had been probed. But
>> why should prepare_namespace() have to wait that long? Wouldn't it be
>> better to wait only until the root device has been registered?
>
> Yes, maybe David should merge the following patch into the patch
> No.5(initdev:kernel: USB and SCSI block init device notification, v3).
>
> Right?
Also need all block device drivers use initdev_*, much work to do,:-)
>
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index dd7ee5f..22fd773 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -358,6 +358,12 @@ void __init mount_root(void)
> #endif
> }
>
> +static int root_dev_done()
> +{
> + return !!(ROOT_DEV = name_to_dev_t(saved_root_name));
> +}
> +
> +
> /*
> * Prepare the namespace - decide what/where to mount, load ramdisks,
> etc. */
> @@ -398,12 +404,12 @@ void __init prepare_namespace(void)
> goto out;
>
> /* wait for any asynchronous scanning to complete */
> - if ((ROOT_DEV == 0) && root_wait) {
> + if (ROOT_DEV == 0 && root_wait) {
> printk(KERN_INFO "Waiting for root device %s...\n",
> saved_root_name);
> - while (driver_probe_done() != 0 ||
> - (ROOT_DEV = name_to_dev_t(saved_root_name)) ==
> 0)
> - msleep(100);
> + do {
> + initdev_wait(BOOTDEV_BLOCK, root_dev_done);
> + } while (!ROOT_DEV);
> async_synchronize_full();
> }
>
>
>
>
> --
> Lei Ming
>
--
Lei Ming
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