cxlflash: Reorder user context initialization

In order to support cxlflash in the PowerVM environment, underlying
hypervisor APIs have imposed a kernel API ordering change.

For the superpipe access to LUN, user applications need a context.
The cxlflash module creates this context by making a sequence of
cxl calls. In the current code, a context is initialized via
cxl_dev_context_init() followed by cxl_process_element(), a function
that obtains the process element id. Finally, cxl_start_work()
is called to attach the process element.

In the PowerVM environment, a process element id cannot be obtained
from the hypervisor until the process element is attached. The
cxlflash module is unable to create contexts without a valid
process element id.

To fix this problem, cxl_start_work() is called before obtaining
the process element id.
Signed-off-by: Uma Krishnan <ukrishn@linux.vnet.ibm.com>
Acked-by: Matthew R. Ochs <mrochs@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/cxlflash/superpipe.c

@@ -1386,6 +1386,13 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
 		goto out_attach;
 	}
 
+	ctxi = create_context(cfg);
+	if (unlikely(!ctxi)) {
+		dev_err(dev, "%s: Failed to create context! (%d)\n",
+			__func__, ctxid);
+		goto err;
+	}
+
 	ctx = cxl_dev_context_init(cfg->dev);
 	if (IS_ERR_OR_NULL(ctx)) {
 		dev_err(dev, "%s: Could not initialize context %p\n",
@@ -1394,6 +1401,17 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
 		goto err;
 	}
 
+	work = &ctxi->work;
+	work->num_interrupts = attach->num_interrupts;
+	work->flags = CXL_START_WORK_NUM_IRQS;
+
+	rc = cxl_start_work(ctx, work);
+	if (unlikely(rc)) {
+		dev_dbg(dev, "%s: Could not start context rc=%d\n",
+			__func__, rc);
+		goto err;
+	}
+
 	ctxid = cxl_process_element(ctx);
 	if (unlikely((ctxid >= MAX_CONTEXT) || (ctxid < 0))) {
 		dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
@@ -1411,27 +1429,9 @@ static int cxlflash_disk_attach(struct scsi_device *sdev,
 	/* Translate read/write O_* flags from fcntl.h to AFU permission bits */
 	perms = SISL_RHT_PERM(attach->hdr.flags + 1);
 
-	ctxi = create_context(cfg);
-	if (unlikely(!ctxi)) {
-		dev_err(dev, "%s: Failed to create context! (%d)\n",
-			__func__, ctxid);
-		goto err;
-	}
-
 	/* Context mutex is locked upon return */
 	init_context(ctxi, cfg, ctx, ctxid, fd, file, perms);
 
-	work = &ctxi->work;
-	work->num_interrupts = attach->num_interrupts;
-	work->flags = CXL_START_WORK_NUM_IRQS;
-
-	rc = cxl_start_work(ctx, work);
-	if (unlikely(rc)) {
-		dev_dbg(dev, "%s: Could not start context rc=%d\n",
-			__func__, rc);
-		goto err;
-	}
-
 	rc = afu_attach(cfg, ctxi);
 	if (unlikely(rc)) {
 		dev_err(dev, "%s: Could not attach AFU rc %d\n", __func__, rc);
@@ -1532,24 +1532,24 @@ static int recover_context(struct cxlflash_cfg *cfg, struct ctx_info *ctxi)
 		goto out;
 	}
 
+	rc = cxl_start_work(ctx, &ctxi->work);
+	if (unlikely(rc)) {
+		dev_dbg(dev, "%s: Could not start context rc=%d\n",
+			__func__, rc);
+		goto err1;
+	}
+
 	ctxid = cxl_process_element(ctx);
 	if (unlikely((ctxid >= MAX_CONTEXT) || (ctxid < 0))) {
 		dev_err(dev, "%s: ctxid (%d) invalid!\n", __func__, ctxid);
 		rc = -EPERM;
-		goto err1;
+		goto err2;
 	}
 
 	file = cxl_get_fd(ctx, &cfg->cxl_fops, &fd);
 	if (unlikely(fd < 0)) {
 		rc = -ENODEV;
 		dev_err(dev, "%s: Could not get file descriptor\n", __func__);
-		goto err1;
-	}
-
-	rc = cxl_start_work(ctx, &ctxi->work);
-	if (unlikely(rc)) {
-		dev_dbg(dev, "%s: Could not start context rc=%d\n",
-			__func__, rc);
 		goto err2;
 	}
 
@@ -1594,10 +1594,10 @@ static int recover_context(struct cxlflash_cfg *cfg, struct ctx_info *ctxi)
 	return rc;
 
 err3:
-	cxl_stop_context(ctx);
-err2:
 	fput(file);
 	put_unused_fd(fd);
+err2:
+	cxl_stop_context(ctx);
 err1:
 	cxl_release_context(ctx);
 	goto out;