Re: Problem hotplugging USB flashdrive (race?)

[Matthew Dharm <mdharm-usb@one-eyed-alien.net>]

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On Thu, Dec 18, 2003 at 09:53:03AM +0100, Oliver Neukum wrote:
> Am Mittwoch, 17. Dezember 2003 18:47 schrieb Greg KH:
> > On Wed, Dec 17, 2003 at 06:28:13PM +0100, Bertrik Sikken wrote:
> > > >Exactly.  Try putting a sleep before reading the file, or loop on the
> > > >file for a bit before reading it.
> > > 
> > > I can confirm that the sleep works (added a sleep 1 at the start
> > > of the script). Does this suggest an issue in the kernel?
> > 
> > No, it's not a problem with the kernel, it's just something that you
> > need to be aware of in your hotplug scripts.
> 
> Technically, it is a race condition.
> You need to make sure that user space loses the race.

Shouldn't this actually be two separate hotplug events?

One when the unit is physically attached, to load the usb-storage driver.

The second when the SCSI layer has initalized the device, to run the
scsi.agent?

Matt

-- 
Matthew Dharm                              Home: mdharm-usb@one-eyed-alien.net 
Maintainer, Linux USB Mass Storage Driver

A female who groks UNIX?  My universe is collapsing.
					-- Mike
User Friendly, 10/11/1998

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