Re: device_remove_file and disconnect

[Greg KH <greg@kroah.com>]

On Thu, Jun 30, 2005 at 10:31:44PM +0200, matthieu castet wrote:
> >Then they should be fixed.  Any specific examples?
> >
> >
> I am a little lasy to list all, but some drivers in driver/usb should 
> have this problem : the first driver I look : ./misc/phidgetkit.c do 
> [1]. So sysfs read don't check if to_usb_interface or usb_get_intfdata 
> return NULL pointer...
> And it is a bit your fault, as many developper should have read your 
> great tutorial [2] ;)

You are correct, I'll go fix those drivers, thanks for pointing it out.
Others pointed out the same thing this week at OLS :)

> >>Also I always see driver free their privatre data in device disconnect,
> >>so if read/write from sysfs aren't serialized with device disconnect
> >>there are still a possible race like I show in my example.
> >
> >
> >Yes, you are correct.  Again, any specific drivers you see with this
> >problem?
> I believe near all drivers that use sysfs via device_create_file, as I 
> never see them use mutex in read/write in order to check there aren't in 
> the same time in their disconnect that could free there private data 
> when they do operation on it...
> 
> 
> Couldn't be possible the make device_remove_file blocking until all the 
> open file are closed ?

Hm, do we even know that those files are opened then?  I'll poke around
in sysfs and see if we could do that.

thanks,

greg k-h