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

Ondrej Zary
2016-10-30T10:50:01Z

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 <linux@rainbow-software.org>
---
drivers/scsi/g_NCR5380.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c
index 3790ed5..f0c5b10 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 +283,29 @@ 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);
+ 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