On 02/25/2013 03:39 PM, Anders Blomdell wrote:
On 2013-02-25 13:27, Gilles Chanteperdrix wrote:
On 02/25/2013 11:18 AM, Anders Blomdell wrote:

On 2013-02-15 16:26, Jan Kiszka wrote:
On 2013-02-15 16:15, Anders Blomdell wrote:
Hi,

I have a DX79SI that dies with "kernel BUG at
arch/x86/kernel/ipipe.c:589!" when running Xenomai. This is not very
surprising since when running the system with an ordinary kernel thera
are a few 'do_IRQ: X.Y No irq handler for vector (irq -1)' each day.

Question is if it would be possible to do something less fatal than
'BUG_ON(irq < 0);' in the code below:

This remains a bug that has to be understood.


int __ipipe_handle_irq(struct pt_regs *regs)
{
      struct ipipe_percpu_data *p =
__ipipe_this_cpu_ptr(&ipipe_percpu);
      int irq, vector = regs->orig_ax, flags = 0;
      struct pt_regs *tick_regs;

      if (likely(vector < 0)) {
          irq = __this_cpu_read(vector_irq[~vector]);
          BUG_ON(irq < 0);
      } else { /* Software-generated. */
          irq = vector;
          flags = IPIPE_IRQF_NOACK;
      }

Kernel 3.5.7 with latest I-pipe?
Yes.

This is the second report of this kind,
see [1] for the discussion and suggestions. If you don't have KGDB and
that kind enabled, try Gilles' instrumentations.
After a running xenomai five and a half day on a DX58SO motherboard, the
system crashed, leaving a single 'do_IRQ: 2.166 No irq handler for
vector (irq -1)' on our logserver.

I'm planning to put in Gilles instrumentations and change the BUG_ON to
a WARN_ON/WARN, but what should I return after that (my guess is a
'return 1', but waiting a week to be proved wrong would be a waste of
time :-).


Returning 1 is incorrect:
- you should probably jump to the end of the __ipipe_handle_irq function
- if the irq is irq 7, meaning a spurious irq, Linux should handle it,
so, __ipipe_dispatch_irq should be called.
OK, so you mean that I'm probably lokking at two different problems
DX58SO: a spurious interrupt (irq==7) passes through __ipipe_handle_irq
without triggering BUG_ON, but something else breaks.
DX79SI: some (spurious?) interrupt results in irq < 0, triggering BUG_ON

Would the following changes be what you have in mind:

     if (likely(vector < 0)) {
         irq = __this_cpu_read(vector_irq[~vector]);
             if (irq < 0) {
                 WARN(irq < 0, "irq(%d) < 0", irq);
                goto out:
          }
     } else { /* Software-generated. */
         irq = vector;
         flags = IPIPE_IRQF_NOACK;
     }
     ...
out:
     return 1;


        ...
        goto out;
        ...

out:
        if (!__ipipe_root_p ||
            test_bit(IPIPE_STALL_FLAG, &__ipipe_root_status))
                return 0;

        return 1;

Returning non-zero means: "context is regular, pass irq to linux normally", and therefore let do_IRQ handle it.

The interrupted context stops being regular linux-wise when the interrupt has preempted the real-time domain (in which case linux might have been preempted in the middle of nowhere by a rt activity), or the root domain is stalled (which means linux does NOT expect that irq to flow down to it, yet).

--
Philippe.

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