scsi/ipr: Fix runaway IRQs when falling back from MSI to LSI

LSIs must be ack'ed with an MMIO otherwise they remain asserted forever. This is controlled by the "clear_isr" flag.

While we set that flag properly when deciding initially whether to use LSIs or MSIs, we fail to set it if we first chose MSIs, the test fails, then fallback to LSIs.

---
 drivers/scsi/ipr.c | 1 +
 1 file changed, 1 insertion(+)

index 5324741..5dd3194 100644
@@ -10213,6 +10213,7 @@ static int ipr_probe_ioa(struct pci_dev *pdev,
 			}
 
 			ioa_cfg->intr_flag = IPR_USE_LSI;
+			ioa_cfg->clear_isr = 1;
 			ioa_cfg->nvectors = 1;
 		}
 		else if (rc)

Benjamin> LSIs must be ack'ed with an MMIO otherwise they remain Benjamin> asserted forever. This is controlled by the "clear_isr" flag.

Benjamin> While we set that flag properly when deciding initially Benjamin> whether to use LSIs or MSIs, we fail to set it if we first Benjamin> chose MSIs, the test fails, then fallback to LSIs.

Brian: Please review!

Martin K. Petersen	Oracle Linux Engineering

Looks good. Thanks! Here is an updated version that should apply cleanly on top of scsi-next.

8<
From: Benjamin Herrenschmidt <[email protected]>

LSIs must be ack'ed with an MMIO otherwise they remain asserted forever. This is controlled by the "clear_isr" flag.

While we set that flag properly when deciding initially whether to use LSIs or MSIs, we fail to set it if we first chose MSIs, the test fails, then fallback to LSIs.

---

 drivers/scsi/ipr.c |    1 +
 1 file changed, 1 insertion(+)

diff -puN drivers/scsi/ipr.c~ipr_misx_fail_intx_clear_isr drivers/scsi/ipr.c
@@ -10157,6 +10157,7 @@ static int ipr_probe_ioa(struct pci_dev
 			pci_free_irq_vectors(pdev);
 
 			ioa_cfg->nvectors = 1;
+			ioa_cfg->clear_isr = 1;
 			break;
 		default:
 			goto out_msi_disable;

_

Brian> Looks good. Thanks! Here is an updated version that should apply Brian> cleanly on top of scsi-next.

Applied to 4.10/scsi-queue. Thanks!

Martin K. Petersen	Oracle Linux Engineering