Jens Axboe <axboe@xxxxxxxxx> writes: > On 2011-03-07 20:33, Jeff Moyer wrote: >> Tejun Heo <tj@xxxxxxxxxx> writes: >> >>> Hello, Jens. >>> >>> On Wed, Mar 02, 2011 at 08:46:46AM -0500, Jens Axboe wrote: >>>>> Right, thanks. Jens, after you apply the two fixes for 2.6.38, I can >>>>> create a merge branch for for-2.6.39/core which you can pull. Would >>>>> that work for you? >>>> >>>> Thanks, that would be great. I'm applying them now. >>> >>> Okay, please pull from the following branch to receive the merge >>> between linux-2.6-block:for-linus and :for-2.6.39/core. >>> >>> git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git block-for-2.6.39-core >>> >>> HEAD is e83a46bbb1d4c03defd733a64b727632a40059ad but git.korg seems a >>> bit slow to sync, so if you don't see the commit there, please pull >>> from master.korg. >>> >>> ssh://master.kernel.org/pub/scm/linux/kernel/git/tj/misc.git block-for-2.6.39-core >>> >>> Thanks. >> >> I know I'm coming to the party late (and maybe wrong), but I've got some >> questions here. >> >> Tejun, you introduced a commit to the ide driver that made it block in >> its request function. As far as I know, that's not allowed. For scsi, >> at least, it has always allowed calling back into the request function >> from the completion handler, and I think this is actully the common case >> (not some corner case). >> >> So, why doesn't the ide driver see calls back into its request function >> from the completion handler? It's clear that it calls blk_end_request >> from ide_end_rq, which can definitely call __blk_run_queue. In other >> words, why is it that the flush requests are triggerring this problem >> while normal I/O isn't? >> >> I think the real issue may just be that the ide driver is blocking in >> its request function. What have I missed? > > So the only case where the request_fn is called and you cannot block, is > if you call it from your completion function. Any other invocation > should be from process context. As long as you remember to drop the > queue lock and re-enable interrupts, it should work. It's not great > style and I would not recommend it for a performance environment, but it > should work. So are you agreeing with me or disagreeing? ;-) It sounds to me like you're saying that the ide driver should be able to cope with being called from softirq context. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
