Messages in this thread | | | Date | Thu, 19 Jun 2003 14:16:58 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH] 2.4 preemption bug in bh_kmap_irq |
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On Tue, Jun 17 2003, Robert Love wrote: > On Mon, 2003-04-14 at 10:27, Joe Korty wrote: > > > The bug is that bh_map_irq *conditionally* calls kmap_atomic (which > > disables preemption as one of its functions), while bh_unmap_irq > > *unconditionally* calls kunmap_atomic (which enables it). This > > imbalance results in a occasional off-by-one preempt_count, which in > > turn causes IDE PIO mode interrupt code (specifically, read_intr) to > > erronously invoke preempt_schedule while at interrupt level. > > Thanks for this (and sorry for the very delayed reply). > > I am going to put this in the 2.4.21 preempt-kernel patch, because > actually someone else here at MontaVista fixed the problem in the same > exact way a loooong time ago and it seems to work. > > I agree it is suboptimal and I will be happy to take patches from > someone else with a better idea. Until then, simplicity rules. Thanks.
See 2.5 for the right fix.
-- Jens Axboe
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