Messages in this thread | | | Date | Tue, 14 Nov 2006 12:52:14 +0100 | From | Pierre Ossman <> | Subject | Re: How to cleanly shut down a block device |
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Jens Axboe wrote: > I think you are making this way too complicated, it's actually pretty > simple: you call blk_put_queue() or blk_cleanup_queue() (same thing) > when _you_ drop your reference to the queue. That's just normal cleanup. > When a device goes away, you make sure that you know about this. I said > that SCSI clears q->queuedata, so it knows that when ->request_fn is > invoked with a NULL q->queuedata (where it stores the device pointer), > the device is not there and the request should just be flushed to > heaven. >
What about the gendisk object? Since I assigned the queue pointer to it, it didn't naturally get a chance to increase the reference count. When can I safely drop my reference without the gendisk getting upset?
> Don't make any assumptions about when request_fn will be called or not. > That's bound to be racy anyway. > >
Things get a bit muddy by the fact that the mmc layer has a thread that handles the queue. So I guess we need to have a way to shut down that thread, but still be able to throw away any stray requests from the block layer?
Rgds
-- -- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org PulseAudio, core developer http://pulseaudio.org rdesktop, core developer http://www.rdesktop.org
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