Am 07.10.2010 13:57, Pavel Machek wrote:
> Hi!
>
> I have... quite an interesting setup here.
>
> SMP machine, with special PCI card; that card has GPIOs and serial
> ports. Unfortunately, there's only one interrupt, shared between
> serials and GPIO pins, and serials are way too complex to be handled
> by realtime layer.
>
> So I ended up with
>
> // we also have an interrupt handler:
>
>
> ret = rtdm_irq_request(&my_context->irq_handle,
> gpio_rt_config.irq, demo_interrupt,
> RTDM_IRQTYPE_SHARED,
> context->device->proc_name, my_context);
>
> and
>
> static int demo_interrupt(rtdm_irq_t *irq_context)
> {
> struct demodrv_context *ctx;
> int dev_id;
> int ret = RTDM_IRQ_HANDLED; // usual return value
>
>
> unsigned pending, output;
>
> ctx = rtdm_irq_get_arg(irq_context, struct demodrv_context);
> dev_id = ctx->dev_id;
>
> if (!ctx->ready) {
> printk(KERN_CRIT "Unexpected interrupt\n");
> return XN_ISR_PROPAGATE;
Who sets ready and when? Looks racy.
> }
>
> rtdm_lock_get(&ctx->lock);
>
> pending = pgread(GPIO_IRQ_ID);
> pgwrite(0, GPIO_IRQ_ID);
> output = pgread(GPIO_STATUS_OUT);
> output ^= (1<<3);
> pgwrite(output, GPIO_STATUS_OUT);
>
> // do stuff
>
>
> if (events > 1000) {
> rtdm_event_signal(&ctx->irq_event);
> events = 0;
> }
> events++;
>
> rtdm_lock_put(&ctx->lock);
>
> /* We need to propagate the interrupt, so that PMC-6L serials
>
>
> work. Result is that interrupt latencies can't be
>
>
> guaranteed when serials are in use. */
>
> return RTDM_IRQ_HANDLED;
> }
>
> Unregistration is:
> my_context->ready = 0;
> rtdm_irq_disable(&my_context->irq_handle);
Where is rtdm_irq_free? Again, this ready flag looks racy.
>
>
> Unfortunately, when the userspace app is ran and killed repeatedly (so
> that interrupt is registered/unregistered all the time), I get
> oopses in __ipipe_dispatch_wired() -- it seems to call into the NULL
> pointer.
>
> I decided that "wired" interrupt when the source is shared between
> Linux and Xenomai, is wrong thing, so I disable "wired" interrupts
> altogether, but that only moved oops to __virq_end.
This is wrong. The only way to get a determistically shared IRQs across
domains is via the wired path, either using the pattern Gilles cited or,
in a slight variation, signaling down via a separate rtdm_nrtsig.
>
> I'm using 2.6.27.21-ELinOS-46 with xenomai-2.4.7 . Problem does go
> away if I boot with maxcpus=1.
>
> Any ideas? (Besides using non-historic kernel; but that's
> unfortunately not exactly easy here.)
>
> Pavel
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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