Re: Please revert 5adc55da4a7758021bcc374904b0f8b076508a11 (PCI_MULTITHREAD_PROBE)

[David Miller <davem@davemloft.net>]

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 8 May 2007 13:01:21 -0700 (PDT)

> In fact, there is nothing wrong with having *both* a synchronous part, and 
> an async part:
> 
> 	.probe = mydriver_setup,
> 	.probe_async = mydriver_spin_up_and_probe_devices,
 ...
> Hmm? Would something like this work? I dunno, but it seems a hell of a lot 
> safer and more capable than the aborted PCI multithreaded probing that was 
> an "all or nothing" approach.

I definitely agree that we need a transitonary approach to this.

Although I kind of preferred the idea you mentioned where the
device could launch the asynchronous probe and just return from
the normal ->probe() immediately.

This might get tricky if the callers do some kind of reference
counting or other resource management based upon the ->probe()
return value since it wouldn't know what happened to the
launched asynchronous probe when it returns from ->probe().