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.
Robert Love
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This archive was generated by hypermail 2b29 : Mon Jun 23 2003 - 22:00:23 EST