lkml.org 
[lkml]   [2006]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC] [PATCH] Fix misrouted interrupts deadlocks
    On Fri, Nov 10, 2006 at 04:55:48PM +0300, Pavel Emelianov wrote:
    > As the second lock on booth CPUs is taken before checking that
    > this irq is being handled in another processor this may cause
    > a deadlock. This issue is only theoretical.
    >
    > I propose the attached patch to fix booth problems: when trying
    > to handle misrouted IRQ active desc->lock may be unlocked.
    >
    > Please comment.

    > --- ./kernel/irq/spurious.c.irqlockup 2006-11-09 11:19:10.000000000 +0300
    > +++ ./kernel/irq/spurious.c 2006-11-10 16:53:38.000000000 +0300
    > @@ -147,7 +147,11 @@ void note_interrupt(unsigned int irq, st
    > if (unlikely(irqfixup)) {
    > /* Don't punish working computers */
    > if ((irqfixup == 2 && irq == 0) || action_ret == IRQ_NONE) {
    > - int ok = misrouted_irq(irq);
    > + int ok;
    > +
    > + spin_unlock(&desc->lock);
    > + ok = misrouted_irq(irq);
    > + spin_lock(&desc->lock);

    Hi Pavel,

    Till -rc5, I was able to boot a kernel with irqpoll option and in -rc6 I
    can't. It simply hangs. I suspect it is realted to this change. I have yet
    to confirm that. But before that one observation.

    Not at every place note_interrupt() is called with desc->lock() held. For
    example, handle_level_irq(). I enabled spin lock debugging and I run into
    following BUG().


    PID hash table entries: 256 (order: 8, 2048 bytes)
    time.c: Using 3.579545 MHz WALL PM GTOD PIT/TSC timer.
    time.c: Detected 3000.218 MHz processor.

    =====================================
    [ BUG: bad unlock balance detected! ]
    -------------------------------------
    swapper/0 is trying to release lock (&irq_desc_lock_class) at:
    [<ffffffff8104c673>] note_interrupt+0x7a/0x22b
    but there are no more locks to release!

    other info that might help us debug this:
    no locks held by swapper/0.

    stack backtrace:

    Call Trace:
    [<ffffffff8100a6f9>] show_trace+0x34/0x47
    [<ffffffff8100a71e>] dump_stack+0x12/0x17
    [<ffffffff8103caba>] print_unlock_inbalance_bug+0xfb/0x106
    [<ffffffff8103e6e5>] lock_release+0x89/0x128
    [<ffffffff81332d96>] _spin_unlock+0x17/0x20
    [<ffffffff8104c673>] note_interrupt+0x7a/0x22b
    [<ffffffff8104d131>] handle_level_irq+0xab/0xea
    [<ffffffff8100b776>] do_IRQ+0xf4/0x132
    [<ffffffff81009956>] ret_from_intr+0x0/0xf
    DWARF2 unwinder stuck at ret_from_intr+0x0/0xf
    Leftover inexact backtrace:

    <IRQ> <EOI> [<ffffffff8159f61d>] start_kernel+0x178/0x2f6
    [<ffffffff8159f625>] start_kernel+0x180/0x2f6
    [<ffffffff8159f61d>] start_kernel+0x178/0x2f6
    [<ffffffff8159f13e>] _sinittext+0x13e/0x142

    BUG: spinlock lockup on CPU#0, swapper/0, ffffffff81586140

    Call Trace:
    [<ffffffff8100a6f9>] show_trace+0x34/0x47
    [<ffffffff8100a71e>] dump_stack+0x12/0x17
    [<ffffffff811457c8>] _raw_spin_lock+0xca/0xe8
    [<ffffffff8104d139>] handle_level_irq+0xb3/0xea
    [<ffffffff8100b776>] do_IRQ+0xf4/0x132
    [<ffffffff81009956>] ret_from_intr+0x0/0xf
    DWARF2 unwinder stuck at ret_from_intr+0x0/0xf

    Leftover inexact backtrace:

    <IRQ> <EOI> [<ffffffff8159f61d>] start_kernel+0x178/0x2f6
    [<ffffffff8159f625>] start_kernel+0x180/0x2f6
    [<ffffffff8159f61d>] start_kernel+0x178/0x2f6
    [<ffffffff8159f13e>] _sinittext+0x13e/0x142

    Thanks
    Vivek
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-11-20 20:27    [W:0.024 / U:0.052 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site