Re: Totally broken PCI PM calls

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> A "hang" sounds like the pmcore bug I reported about a year ago...
> 
> It's rather foolish of the PM core to use the same semaphore to
> protect system-wide suspend/resume operations that it uses to
> for mutual exclusion on the device add/remove (which suspend
> and resume callbacks did happily in 2.4) ... since it's routine to
> unplug peripherals on suspended systems!

Definitely. One thing is: how to do it instead ? I've been thinking
about it for a while and am still wondering... do we want a list
mecanism with add/remove notifiers so the PM walk can keep in sync
with devices added/removed ? or should addition/removal be simply
postponed until the end of the sleep/wakeup process (I tend to vote
for that).

> Alternatively, if you're combininging USB_SUSPEND with any
> system-wide suspend operation, you're asking for trouble;
> the PM core is just not ready for that.  (In fact I've wondered
> if maybe 2.6.9 shouldn't discourage that combination more
> actively...)
> 
> But a keyboard-specific issue might be improved with the
> HID patch I posted last week, teaching that driver how to
> handle suspend() and resume() callbacks.
> 
> - Dave
-- 
Benjamin Herrenschmidt <benh@kernel.crashing.org>