udev rule, when RUN script is invoked?

[Alexander Ivanov]

Greg,

On Thu, 22 Feb 2018 08:56 +0100, Greg KH <greg at kroah.com> wrote:
> On Wed, Feb 21, 2018 at 03:36:44PM -0800, Alexander Ivanov wrote:
> > Hi All,
> > 
> > I have udev rule defined on a
> > 
> > DEVPATH="/dev/mydev0",..., ACTION="remove", ..., RUN+="/path/to/script"
> > 
> > When does /path/to/script is executed in respect to module's remove() and exit() ?
> 
> A module's lifecycle is different from a device's lifecycle, right?
> 
Sure. However, in this particular case, only one device for the module can exist and user-land calls insmod/rmmod, Thus, on rmmod both device's remove() and module's exit() are getting called.


> There is no remove() call for a module, only for a driver subsystem, so
> be careful as to what exactly you are referring to here.
> 
> Hopefully, all devices "owned" by the module should be removed from the
> kernel before the module is unloaded, so that should help you out here.
> 
> Also note that modules are never automatically unloaded, so that is
> never a normal operation in the system.
> 
> what exactly are you trying to do here with your udev script?

On action=="remove", I'd like to call device's close(), it was open()ed by action=="add"
It looks like device is removed before RUN gets a chance to execute..

Basically, I need to start reading from device as soon as it appears in the system, and stop it right before it get removed.

thanks,
--Alex

> 
> thanks,
> 
> greg k-h
> 
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-- 
  Alexander Ivanov
  amivanov at fastmail.com