linux-kernel - [PATCH v2 15/19] xen/pcifront: use xenbus_setup_ring() and xenbus_teardown

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Date:   Thu, 28 Apr 2022 10:27:39 +0200
From:   Juergen Gross <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v2 15/19] xen/pcifront: use xenbus_setup_ring() and xenbus_teardown_ring()

Simplify pcifront's shared page creation and removal via
xenbus_setup_ring() and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 drivers/pci/xen-pcifront.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 3edc1565a27c..689271c4245c 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -709,9 +709,8 @@ static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 	if (pdev == NULL)
 		goto out;
 
-	pdev->sh_info =
-	    (struct xen_pci_sharedinfo *)__get_free_page(GFP_KERNEL);
-	if (pdev->sh_info == NULL) {
+	if (xenbus_setup_ring(xdev, GFP_KERNEL, (void **)&pdev->sh_info, 1,
+			      &pdev->gnt_ref)) {
 		kfree(pdev);
 		pdev = NULL;
 		goto out;
@@ -729,7 +728,6 @@ static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 	spin_lock_init(&pdev->sh_info_lock);
 
 	pdev->evtchn = INVALID_EVTCHN;
-	pdev->gnt_ref = INVALID_GRANT_REF;
 	pdev->irq = -1;
 
 	INIT_WORK(&pdev->op_work, pcifront_do_aer);
@@ -754,11 +752,7 @@ static void free_pdev(struct pcifront_device *pdev)
 	if (pdev->evtchn != INVALID_EVTCHN)
 		xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
 
-	if (pdev->gnt_ref != INVALID_GRANT_REF)
-		gnttab_end_foreign_access(pdev->gnt_ref,
-					  (unsigned long)pdev->sh_info);
-	else
-		free_page((unsigned long)pdev->sh_info);
+	xenbus_teardown_ring((void **)&pdev->sh_info, 1, &pdev->gnt_ref);
 
 	dev_set_drvdata(&pdev->xdev->dev, NULL);
 
@@ -769,13 +763,6 @@ static int pcifront_publish_info(struct pcifront_device *pdev)
 {
 	int err = 0;
 	struct xenbus_transaction trans;
-	grant_ref_t gref;
-
-	err = xenbus_grant_ring(pdev->xdev, pdev->sh_info, 1, &gref);
-	if (err < 0)
-		goto out;
-
-	pdev->gnt_ref = gref;
 
 	err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
 	if (err)
-- 
2.34.1