[PATCH 9/11] pcmcia: fix sharing IRQs and request_irq without IRQ_HANDLE_PRESENT

[Dominik Brodowski]

Debugging and description from: Noah Misch <noah at cs.caltech.edu>


When a driver calls pcmcia_request_irq with IRQ_HANDLE_PRESENT unset, it looks
for an open IRQ by request_irq()ing with a dummy handler and NULL dev_info.
free_irq uses dev_info as a key for identifying the handler to free among those
sharing an IRQ, so request_irq returns -EINVAL if dev_info is NULL and the IRQ
may be shared.  That unknown error code is the -EINVAL.

It looks like only pcnet_cs and axnet_cs are affected.  Most other drivers let
pcmcia_request_irq install their interrupt handlers.  sym53c500_cs requests its
IRQ manually, but it cannot share an IRQ.

The appended patch changes pcmcia_request_irq to pass an arbitrary, unique,
non-NULL dev_info with the dummy handler.

Signed-off-by: Dominik Brodowski <linux at dominikbrodowski.net>
---

 drivers/pcmcia/pcmcia_resource.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

Index: 2.6.13-rc3-git2/drivers/pcmcia/pcmcia_resource.c
===================================================================
--- 2.6.13-rc3-git2.orig/drivers/pcmcia/pcmcia_resource.c
+++ 2.6.13-rc3-git2/drivers/pcmcia/pcmcia_resource.c
@@ -800,7 +800,7 @@ int pcmcia_request_irq(struct pcmcia_dev
 	} else {
 		int try;
 		u32 mask = s->irq_mask;
-		void *data = NULL;
+		void *data = &p_dev->dev.driver; /* something unique to this device */
 
 		for (try = 0; try < 64; try++) {
 			irq = try % 32;