Messages in this thread | | | Date | Thu, 27 Feb 2014 22:32:52 +0100 | From | Jan Kara <> | Subject | Re: [PATCH 2/2] bdi: Avoid oops on device removal |
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On Thu 27-02-14 15:07:48, Tejun Heo wrote: > Hello, > > On Tue, Feb 25, 2014 at 11:29:14PM +0100, Jan Kara wrote: > > +static void bdi_wakeup_thread(struct backing_dev_info *bdi) > > +{ > > + spin_lock_bh(&bdi->wb_lock); > > + if (test_bit(BDI_registered, &bdi->state)) > > + mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); > > + spin_unlock_bh(&bdi->wb_lock); > > +} > > I wonder whether this can be smarter without requiring wb_lock each > timer but this probably is the simplest for -stable backports. We could be clever, check whether the work is already queued for execution and bail out without taking wb_lock if yes (that would also save us some unnecessary juggling in try_to_grab_pending() for the situation were the work is already queued). But I'm not sure how to cleanly implement this...
> > static void bdi_queue_work(struct backing_dev_info *bdi, > > struct wb_writeback_work *work) > > { > > trace_writeback_queue(bdi, work); > > > > spin_lock_bh(&bdi->wb_lock); > > + if (!test_bit(BDI_registered, &bdi->state)) { > > + if (work->done) > > + complete(work->done); > > + goto out_unlock; > > + } > > list_add_tail(&work->list, &bdi->work_list); > > - spin_unlock_bh(&bdi->wb_lock); > > - > > mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); > > +out_unlock: > > + spin_unlock_bh(&bdi->wb_lock); > > } > > > > + > > + > > Why three blank lines? A mistake. Will fix.
> Other than that, > > Reviewed-by: Tejun Heo <tj@kernel.org> Thanks!
Honza -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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