Re: Problem hotplugging USB flashdrive (race?)

[Olaf Hering <olh@suse.de>]

 On Sat, Dec 13, Bertrik Sikken wrote:

> Hi all,
> 
> I'm seeing some weird messages in /var/log/messages when
> inserting my USB2.0 flashdrive. Apparently scsi.agent cannot
> determine the type of scsi device that is created by usb-storage.
> When I leave the stick in during boot, it works fine.
> 
> Software:
> * Mandrake 9.2 base system with some modifications:
> * Kernel 2.6.0-test11 (also tried kernel 2.6.0-test11-bk8)
>   SCSI and USB compiled as modules.
> * Hotplug 20030805
> * udev 008
> * sysfs mounted on /sys
> 
> Hardware:
> * Canyon USB2.0 (high speed) 128 MB flashdrive, with
>   an embedded hub.
> * EHCI controller (UHCI controller gives same problem)
> 
> I think what happens when inserting the flash drive is this:
> hotplug sees the embedded hub and mass-storage device in the
> USB stick and loads usb-storage and SCSI modules. Then it
> seems that scsi.agent tries to extract a number from the file
> /sys/devices/<.....>/type
> which appears to be an empty string according to the log.
> When I try to cat this file manually, it exists and it
> results in the number 0, which correctly indicates a
> SCSI disk with associated module sd_mod.
> I can imagine that this is some kind of race condition,
> where the script looks too soon for the file or its contents.
> 
> Is this a known problem?
> What kind of logging / information is required to investigate this?

Is your device seen as a block device? If so, do you react on the block
event or on the events before the block event? I'm almost sure you care
about stuff like 'sdX' or similar. So doing something from usb.agent or
scsi.agent is obviously wrong. Use a block.agent script.

-- 
USB is for mice, FireWire is for men!

sUse lINUX ag, n√úRNBERG


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