[PATCH 00/18] xen: simplify frontend side ring setup

[PATCH 00/18] xen: simplify frontend side ring setup

[Juergen Gross]

Many Xen PV frontends share similar code for setting up a ring page
(allocating and granting access for the backend) and for tearing it
down.

Create new service functions doing all needed steps in one go.

This requires all frontends to use a common value for an invalid
grant reference in order to make the functions idempotent.

Juergen Gross (18):
  xen/blkfront: switch blkfront to use INVALID_GRANT_REF
  xen/netfront: switch netfront to use INVALID_GRANT_REF
  xen/scsifront: remove unused GRANT_INVALID_REF definition
  xen/usb: switch xen-hcd to use INVALID_GRANT_REF
  xen/drm: switch xen_drm_front to use INVALID_GRANT_REF
  xen/sound: switch xen_snd_front to use INVALID_GRANT_REF
  xen/dmabuf: switch gntdev-dmabuf to use INVALID_GRANT_REF
  xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF
  xen/xenbus: add xenbus_setup_ring() service function
  xen/blkfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/netfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/drmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/pcifront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/scsifront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/sndfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/xenbus: eliminate xenbus_grant_ring()

 drivers/block/xen-blkfront.c                | 54 ++++----------
 drivers/char/tpm/xen-tpmfront.c             | 18 +----
 drivers/gpu/drm/xen/xen_drm_front.h         |  9 ---
 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 40 +++-------
 drivers/net/xen-netfront.c                  | 77 ++++++--------------
 drivers/pci/xen-pcifront.c                  | 19 +----
 drivers/scsi/xen-scsifront.c                | 30 ++------
 drivers/usb/host/xen-hcd.c                  | 59 ++++-----------
 drivers/xen/gntdev-dmabuf.c                 | 13 +---
 drivers/xen/xen-front-pgdir-shbuf.c         | 17 +----
 drivers/xen/xenbus/xenbus_client.c          | 81 ++++++++++++++++-----
 include/xen/xenbus.h                        |  4 +-
 sound/xen/xen_snd_front_evtchnl.c           | 41 +++--------
 sound/xen/xen_snd_front_evtchnl.h           |  9 ---
 14 files changed, 156 insertions(+), 315 deletions(-)

-- 
2.34.1

[PATCH 04/18] xen/usb: switch xen-hcd to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/usb/host/xen-hcd.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
index 3e487baf8422..9cbc7c2dab02 100644
--- a/drivers/usb/host/xen-hcd.c
+++ b/drivers/usb/host/xen-hcd.c
@@ -87,8 +87,6 @@ struct xenhcd_info {
 	bool error;
 };
 
-#define GRANT_INVALID_REF 0
-
 #define XENHCD_RING_JIFFIES (HZ/200)
 #define XENHCD_SCAN_JIFFIES 1
 
@@ -1100,17 +1098,17 @@ static void xenhcd_destroy_rings(struct xenhcd_info *info)
 		unbind_from_irqhandler(info->irq, info);
 	info->irq = 0;
 
-	if (info->urb_ring_ref != GRANT_INVALID_REF) {
+	if (info->urb_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(info->urb_ring_ref,
 					  (unsigned long)info->urb_ring.sring);
-		info->urb_ring_ref = GRANT_INVALID_REF;
+		info->urb_ring_ref = INVALID_GRANT_REF;
 	}
 	info->urb_ring.sring = NULL;
 
-	if (info->conn_ring_ref != GRANT_INVALID_REF) {
+	if (info->conn_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(info->conn_ring_ref,
 					  (unsigned long)info->conn_ring.sring);
-		info->conn_ring_ref = GRANT_INVALID_REF;
+		info->conn_ring_ref = INVALID_GRANT_REF;
 	}
 	info->conn_ring.sring = NULL;
 }
@@ -1123,8 +1121,8 @@ static int xenhcd_setup_rings(struct xenbus_device *dev,
 	grant_ref_t gref;
 	int err;
 
-	info->urb_ring_ref = GRANT_INVALID_REF;
-	info->conn_ring_ref = GRANT_INVALID_REF;
+	info->urb_ring_ref = INVALID_GRANT_REF;
+	info->conn_ring_ref = INVALID_GRANT_REF;
 
 	urb_sring = (struct xenusb_urb_sring *)get_zeroed_page(
 							GFP_NOIO | __GFP_HIGH);
-- 
2.34.1

[PATCH 16/18] xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify xen-hcd's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/usb/host/xen-hcd.c | 55 +++++++++-----------------------------
 1 file changed, 13 insertions(+), 42 deletions(-)

diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
index 9cbc7c2dab02..0acb68eb37ee 100644
--- a/drivers/usb/host/xen-hcd.c
+++ b/drivers/usb/host/xen-hcd.c
@@ -1098,19 +1098,10 @@ static void xenhcd_destroy_rings(struct xenhcd_info *info)
 		unbind_from_irqhandler(info->irq, info);
 	info->irq = 0;
 
-	if (info->urb_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(info->urb_ring_ref,
-					  (unsigned long)info->urb_ring.sring);
-		info->urb_ring_ref = INVALID_GRANT_REF;
-	}
-	info->urb_ring.sring = NULL;
-
-	if (info->conn_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(info->conn_ring_ref,
-					  (unsigned long)info->conn_ring.sring);
-		info->conn_ring_ref = INVALID_GRANT_REF;
-	}
-	info->conn_ring.sring = NULL;
+	xenbus_teardown_ring((void **)&info->urb_ring.sring, 1,
+			     &info->urb_ring_ref);
+	xenbus_teardown_ring((void **)&info->conn_ring.sring, 1,
+			     &info->conn_ring_ref);
 }
 
 static int xenhcd_setup_rings(struct xenbus_device *dev,
@@ -1118,47 +1109,27 @@ static int xenhcd_setup_rings(struct xenbus_device *dev,
 {
 	struct xenusb_urb_sring *urb_sring;
 	struct xenusb_conn_sring *conn_sring;
-	grant_ref_t gref;
 	int err;
 
-	info->urb_ring_ref = INVALID_GRANT_REF;
 	info->conn_ring_ref = INVALID_GRANT_REF;
-
-	urb_sring = (struct xenusb_urb_sring *)get_zeroed_page(
-							GFP_NOIO | __GFP_HIGH);
-	if (!urb_sring) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating urb ring");
-		return -ENOMEM;
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+				(void **)&urb_sring, 1, &info->urb_ring_ref);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "allocating urb ring");
+		return err;
 	}
 	SHARED_RING_INIT(urb_sring);
 	FRONT_RING_INIT(&info->urb_ring, urb_sring, PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, urb_sring, 1, &gref);
-	if (err < 0) {
-		free_page((unsigned long)urb_sring);
-		info->urb_ring.sring = NULL;
-		goto fail;
-	}
-	info->urb_ring_ref = gref;
-
-	conn_sring = (struct xenusb_conn_sring *)get_zeroed_page(
-							GFP_NOIO | __GFP_HIGH);
-	if (!conn_sring) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating conn ring");
-		err = -ENOMEM;
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+				(void **)&conn_sring, 1, &info->conn_ring_ref);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "allocating conn ring");
 		goto fail;
 	}
 	SHARED_RING_INIT(conn_sring);
 	FRONT_RING_INIT(&info->conn_ring, conn_sring, PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, conn_sring, 1, &gref);
-	if (err < 0) {
-		free_page((unsigned long)conn_sring);
-		info->conn_ring.sring = NULL;
-		goto fail;
-	}
-	info->conn_ring_ref = gref;
-
 	err = xenbus_alloc_evtchn(dev, &info->evtchn);
 	if (err) {
 		xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
-- 
2.34.1

Re: [PATCH 04/18] xen/usb: switch xen-hcd to use INVALID_GRANT_REF

[Greg Kroah-Hartman]

On Wed, Apr 20, 2022 at 05:09:28PM +0200, Juergen Gross wrote:
> Instead of using a private macro for an invalid grant reference use
> the common one.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  drivers/usb/host/xen-hcd.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH 16/18] xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Greg Kroah-Hartman]

On Wed, Apr 20, 2022 at 05:09:40PM +0200, Juergen Gross wrote:
> Simplify xen-hcd's ring creation and removal via xenbus_setup_ring()
> and xenbus_teardown_ring().
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
>  drivers/usb/host/xen-hcd.c | 55 +++++++++-----------------------------
>  1 file changed, 13 insertions(+), 42 deletions(-)

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>