Messages in this thread | | | Date | Mon, 6 Oct 2008 05:02:46 -0400 | From | Alan Cox <> | Subject | Re: [PATCH 38/76] tty: usb-serial krefs |
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On Sun, Oct 05, 2008 at 10:36:58PM -0700, Greg KH wrote: > Should we be calling kref_get() and kref_put() in interrupt context? > Could we just get the reference in open and then put in close when we > are done with it for each driver?
That depends how you handle hangups and interrupt synchronization. If you can be sure you will get no more interrupts before you drop the reference in close/hangup then yes that should be fine. In particular watch out for the fact that hangup/close/re-open can run pretty much in parallel with cases like
close called by user interrupted by carrier drop causing hangup
in parallel another open begins and blocks waiting a close
(Obviously for hotplug some further care is needed on the unplug paths)
Right now USB serial doesn't actually address all those cases anyway I suspect. I wasn't going to attack that until I had a common tty_port and tty_port code to do all that work rather than trying to fix each group of drivers.
Alan
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