[SCSI] ibmvscsi: Fix softlockup on resume

This fixes a softlockup seen on resume. During resume, the CRQ
must be reenabled. However, the H_ENABLE_CRQ hcall used to do
this may return H_BUSY or H_LONG_BUSY. When this happens, the
caller is expected to retry later. This patch changes a simple
loop, which was causing the softlockup, to a loop at task level
which sleeps between retries rather than simply spinning.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 13 insertions, 3 deletions

diff --git a/drivers/scsi/ibmvscsi/rpa_vscsi.c b/drivers/scsi/ibmvscsi/rpa_vscsi.c
index 989b9a8ba72..f48ae0190d9 100644
--- a/drivers/scsi/ibmvscsi/rpa_vscsi.c
+++ b/drivers/scsi/ibmvscsi/rpa_vscsi.c
@@ -31,6 +31,7 @@
 #include <asm/prom.h>
 #include <asm/iommu.h>
 #include <asm/hvcall.h>
+#include <linux/delay.h>
 #include <linux/dma-mapping.h>
 #include <linux/gfp.h>
 #include <linux/interrupt.h>
@@ -71,11 +72,13 @@ static void rpavscsi_release_crq_queue(struct crq_queue *queue,
 				       struct ibmvscsi_host_data *hostdata,
 				       int max_requests)
 {
-	long rc;
+	long rc = 0;
 	struct vio_dev *vdev = to_vio_dev(hostdata->dev);
 	free_irq(vdev->irq, (void *)hostdata);
 	tasklet_kill(&hostdata->srp_task);
 	do {
+		if (rc)
+			msleep(100);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
 	dma_unmap_single(hostdata->dev,
@@ -200,11 +203,13 @@ static void set_adapter_info(struct ibmvscsi_host_data *hostdata)
 static int rpavscsi_reset_crq_queue(struct crq_queue *queue,
 				    struct ibmvscsi_host_data *hostdata)
 {
-	int rc;
+	int rc = 0;
 	struct vio_dev *vdev = to_vio_dev(hostdata->dev);
 
 	/* Close the CRQ */
 	do {
+		if (rc)
+			msleep(100);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
 
@@ -301,7 +306,10 @@ static int rpavscsi_init_crq_queue(struct crq_queue *queue,
 
       req_irq_failed:
 	tasklet_kill(&hostdata->srp_task);
+	rc = 0;
 	do {
+		if (rc)
+			msleep(100);
 		rc = plpar_hcall_norets(H_FREE_CRQ, vdev->unit_address);
 	} while ((rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));
       reg_crq_failed:
@@ -323,11 +331,13 @@ static int rpavscsi_init_crq_queue(struct crq_queue *queue,
 static int rpavscsi_reenable_crq_queue(struct crq_queue *queue,
 				       struct ibmvscsi_host_data *hostdata)
 {
-	int rc;
+	int rc = 0;
 	struct vio_dev *vdev = to_vio_dev(hostdata->dev);
 
 	/* Re-enable the CRQ */
 	do {
+		if (rc)
+			msleep(100);
 		rc = plpar_hcall_norets(H_ENABLE_CRQ, vdev->unit_address);
 	} while ((rc == H_IN_PROGRESS) || (rc == H_BUSY) || (H_IS_LONG_BUSY(rc)));