[PATCH 2/3] g_NCR5380: Test the IRQ before accepting it

[Ondrej Zary]

Trigger an IRQ first with a test IRQ handler to find out if it really
works. Disable the IRQ if not.

This prevents hang when incorrect IRQ was specified by user.

Signed-off-by: Ondrej Zary <li...@rainbow-software.org>
---
 drivers/scsi/g_NCR5380.c |   32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 3790ed5..261e168 100644
--- a/drivers/scsi/g_NCR5380.c
+++ b/drivers/scsi/g_NCR5380.c
@@ -67,6 +67,14 @@
 MODULE_ALIAS("g_NCR5380_mmio");
 MODULE_LICENSE("GPL");
 
+static bool irq_working;
+
+static irqreturn_t test_irq(int irq, void *dev_id)
+{
+       irq_working = true;
+       return IRQ_HANDLED;
+}
+
 /*
  * Configure I/O address of 53C400A or DTC436 by writing magic numbers
  * to ports 0x779 and 0x379.
@@ -275,10 +283,30 @@ static int generic_NCR5380_init_one(struct 
scsi_host_template *tpnt,
                /* set IRQ for HP C2502 */
                if (board == BOARD_HP_C2502)
                        magic_configure(port_idx, instance->irq, magic);
-               if (request_irq(instance->irq, generic_NCR5380_intr,
-                               0, "NCR5380", instance)) {
+               /* test if the IRQ is working */
+               irq_working = false;
+               if (request_irq(instance->irq, test_irq,
+                               0, "NCR5380-irqtest", NULL)) {
                        printk(KERN_WARNING "scsi%d : IRQ%d not free, 
interrupts disabled\n", instance->host_no, instance->irq);
                        instance->irq = NO_IRQ;
+               } else {
+                       NCR5380_trigger_irq(instance);
+                       NCR5380_read(RESET_PARITY_INTERRUPT_REG);
+                       free_irq(instance->irq, NULL);
+                       if (irq_working) {
+                               if (request_irq(instance->irq,
+                                               generic_NCR5380_intr, 0,
+                                               "NCR5380", instance)) {
+                                       printk(KERN_WARNING "scsi%d : IRQ%d not 
free, interrupts disabled\n",
+                                              instance->host_no,
+                                              instance->irq);
+                                       instance->irq = NO_IRQ;
+                               }
+                       } else {
+                               printk(KERN_WARNING "scsi%d : IRQ%d not 
working, interrupts disabled\n",
+                                      instance->host_no, instance->irq);
+                               instance->irq = NO_IRQ;
+                       }
                }
        }
 
-- 
Ondrej Zary