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    SubjectRE: sata_mv port lockup on hotplug (kernel
    > > One thing I noticed was that there is no spinlock around the
    > > mv_save_cached_regs/mv_edma_cfg in mv_hardreset (unlike mv_port_start
    > > and mv_port_stop); why is this?
    > Yeah, I'm suspecting there's a loophole in the logic there somewhere.
    > I dusted off the 6041 reference card I have here, and played with the cables
    > for a while. Managed to get one port to stop responding to hot plug fairly
    > quickly, though I'm not sure how/why.
    > Then I added a debug printk() to mv_write_main_irq_mask(), with no other
    > changes, and that appears to have been enough to change the race timing
    > so that I could no longer produce the problem.
    > Bruce, here's a slightly-ugly patch that should remove all doubt about races
    > in the irq_mask. Please apply it, test with it, and let me know here if the
    > issue goes away.
    > Thanks
    > [patch]

    Hi Mark,

    I have tried the patch out and I was able to reproduce the port lockup with it.

    I also tried out my tracing in writelfl (without any other changes) and I was
    able to lock up a port without any apparent unusual changes to the register
    containing the irq masks. Are there other routes to disabling the irqs?

    I shall continue looking.



    Bruce Stenning,
    b <dot> stenning <at> indigovision <dot> com

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