On Wed, 17 Jun 2009, Thomas Gleixner wrote:
Errm, and how does udev figure out which device node to create for
which device ?
/sys/devices/pci0000:00/0000:00:1d.7/usb1/dev
Thanks for the hint. I wasn't aware of the need to call
device_create() etc in my driver, and had been creating device files
by hand. Having now remedied this omission, I have taken the
opportunity to add an irq attribute file under each of my device
entries in sysfs. Next I would like to add an attribute that indicates
the corresponding thread PID. To do that, I need a kernel function
that can be called to determine the IRQ thread ID.
I have just written and tested the following function for doing this:
#ifdef CONFIG_PREEMPT_HARDIRQS
pid_t get_irq_thread_pid(unsigned int irq, struct pid_namespace *ns)
{
struct irq_desc *desc = irq_to_desc(irq);
pid_t pid = 0;
if(desc) {
unsigned long flags;
spin_lock_irqsave(&desc->lock, flags);
if(desc->thread)
pid = task_pid_nr_ns(desc->thread, ns);
spin_unlock_irqrestore(&desc->lock, flags);
}
return pid;
}
EXPORT_SYMBOL(get_irq_thread_pid);
#endif
This would most frequently be called like:
pid = get_irq_thread_pid(irq, current->nsproxy->pid_ns);
if(pid) {
...
}
Would this function be acceptible for inclusion in the preempt-rt
kernel, or do you have something else in mind?
Martin
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