lkml.org 
[lkml]   [2011]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patches in this message
    /
    Date
    From
    SubjectRe: sata_mv port lockup on hotplug (kernel 2.6.38.2)
    On 11-04-12 06:30 AM, Bruce Stenning wrote:
    ..
    > I am currently inserting tracing into 2.6.38.2 to try to work out what is going
    > on. From mv_write_main_irq_mask I can see that the IRQ for each port is still
    > enabled, even when ports stop responding.
    ..
    > 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

    --- old/drivers/ata/sata_mv.c 2011-04-13 11:03:07.442481426 -0400
    +++ linux/drivers/ata/sata_mv.c 2011-04-13 11:07:55.224249621 -0400
    @@ -1027,15 +1027,19 @@
    static void mv_set_main_irq_mask(struct ata_host *host,
    u32 disable_bits, u32 enable_bits)
    {
    + static spinlock_t irq_mask_lock = __SPIN_LOCK_UNLOCKED(irq_mask_lock); //
    FIXME: per-host would be nicer
    struct mv_host_priv *hpriv = host->private_data;
    u32 old_mask, new_mask;
    + unsigned long flags;

    + spin_lock_irqsave(&irq_mask_lock, flags);
    old_mask = hpriv->main_irq_mask;
    new_mask = (old_mask & ~disable_bits) | enable_bits;
    if (new_mask != old_mask) {
    hpriv->main_irq_mask = new_mask;
    mv_write_main_irq_mask(new_mask, hpriv);
    }
    + spin_unlock_irqrestore(&irq_mask_lock, flags);
    }

    static void mv_enable_port_irqs(struct ata_port *ap,--- old/drivers/ata/sata_mv.c 2011-04-13 11:03:07.442481426 -0400
    +++ linux/drivers/ata/sata_mv.c 2011-04-13 11:07:55.224249621 -0400
    @@ -1027,15 +1027,19 @@
    static void mv_set_main_irq_mask(struct ata_host *host,
    u32 disable_bits, u32 enable_bits)
    {
    + static spinlock_t irq_mask_lock = __SPIN_LOCK_UNLOCKED(irq_mask_lock); // FIXME: per-host would be nicer
    struct mv_host_priv *hpriv = host->private_data;
    u32 old_mask, new_mask;
    + unsigned long flags;

    + spin_lock_irqsave(&irq_mask_lock, flags);
    old_mask = hpriv->main_irq_mask;
    new_mask = (old_mask & ~disable_bits) | enable_bits;
    if (new_mask != old_mask) {
    hpriv->main_irq_mask = new_mask;
    mv_write_main_irq_mask(new_mask, hpriv);
    }
    + spin_unlock_irqrestore(&irq_mask_lock, flags);
    }

    static void mv_enable_port_irqs(struct ata_port *ap,
    \
     
     \ /
      Last update: 2011-04-13 17:13    [W:0.023 / U:180.576 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site