On 14 May 2004, James Bottomley wrote: > The idea behind scsi_remove_host() was that it was going to be called > from the module_exit() routine. This means that the reference count on > the LLD has already dropped to zero and it's safe for removal. > > If you call scsi_remove_host() outside of the module_exit() code then > what it does is remove all hosts from visibility (and makes it > impossible to open or do anything with them), but it cannot revoke > outstanding references (which may continue to use the device). The > mid-layer takes the devices through CANCEL and then DEL. When > scsi_remove_host() returns, you are guaranteed (barring any state model > cockups) that the devices on the LLD with outstanding references are all > in the DEL state. It will also block the device from above (no commands > will be sent down). Any currently outstanding commands will be errored > from the mid-layer; however, it will do nothing about outstanding > commands in the LLD, you have to deal with them yourself. > > The way this is supposed to work is that when you get a disconnection, > you start refusing commands (and you also discard any active ones). > Then you call scsi_remove_host(). We discard all current commands > > So, if the usb storage LLD isn't discarding the commands, then they may > be active.
Yes, that would explain it. We do arrange to abort the current command, but this is done before calling scsi_remove_host() when it should be done after. And we don't wait for the kernel thread to become idle afterwards. I'll work on a patch. Testing it won't be easy, though; it's hard to prove that a race _isn't_ happening! Alan Stern ------------------------------------------------------- This SF.Net email is sponsored by: SourceForge.net Broadband Sign-up now for SourceForge Broadband and get the fastest 6.0/768 connection for only $19.95/mo for the first 3 months! http://ads.osdn.com/?ad_id=2562&alloc_id=6184&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
