RE: [PATCH net-next v2] misc: Add Renesas Synchronization Management Unit (SMU) support

[Min Li]

> > +
> > +	/* Only one open per device at a time */
> > +	if (!atomic_dec_and_test(&rsmu->open_count)) {
> > +		atomic_inc(&rsmu->open_count);
> > +		return -EBUSY;
> 
> This does not do what you think it does, and does not prevent multiple
> applications from talking to your device at the same time.
> 
> There is no need for this at all, as it does not work, sorry.  If multiple apps
> talk to your device, it's their fault, not the kernel's fault, that things go
> wrong.
> 
> And I thought that Arnd already told you to fix this?
> 

Hi Greg

Sorry for not replying to the list, I am new so not very familiar with the process.

Can you elaborate why it doesn't work? I kind of borrow the idea from xilinx_sdfec.c and I don't see why it doesn't work.

I mean if an application failed at opening the device, how can it proceed to talk the device without a file descriptor?

Thanks

Min