RE: Request_irq fails for IRQ2

On Tue, 2011-10-04 at 13:55 +0000, smitha.vanga@wipro.com wrote:

Hi Scoot,

When I try to use a atomic varaible in my ISR  I see a kernel crash .
with mesage BUG: scheduling while atomic:



Below is the code :
My ISR

irqreturn_t cpld_irq_handler(int irq, void * dev_id, struct pt_regs
*regs)

{

wake_up(&cpld_intr_wait);

atomic_inc(&cpld_intr_data); /* incrementing this will indicate the
poll() that the interrupt is occured */

return 0;

}

This is of course completely racy, you should do the increment -before-
you wake up. I suppose you aren't SMP at the moment but even then, if
you ever switch for example to threaded interrupts or use RT it will
potentially break.

DRIVER_INIT
static int __init gpio_init(void)
{
        int ret = 0;
        int virq;

       
    atomic_set(&cpld_intr_data, 0);                     /* initialize
the Interrupt indicator */
    init_waitqueue_head(&cpld_intr_wait);               /* Initialize
the wait queue */

    virq = irq_create_mapping(NULL, CPLD1_INTERRUPT);

See comments earlier about using the device-tree here.

              
   if ((ret = request_irq(virq,cpld_irq_handler, 0, GPIO_CHAR_PATH,
NULL))!=0)
   {
      printk(KERN_ERR "gpio_init: Could not grab IRQ line for CPLD ret
= %d\n",ret);
          goto err1;
   }
  
 
        if((s_nGPIOMajor = register_chrdev(MPC8247_DEVICE_MAJOR_NUM,
GPIO_CHAR_PATH, &gpio_fops))<0)
        {
                GPIO_DBG2("GPIO_DRIVER  : unable to get major %d\n",
s_nGPIOMajor);
                return s_nGPIOMajor;
               
        }else{
                GPIO_DBG2("GPIO_DRIVER  : major = %x\n", s_nGPIOMajor
);
        }

coding style FAIL

        return 0;
    
} 

I don't see anything that does your scheduling while atomic here,
probably a bug in your poll implementation but it's not here.

Oh and stop sending that crap:

Regards,
Smitha

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It's a complete nonsense on a public mailing list

Ben.