[PATCH v2 0/8] xen/events: bug fixes and some diagnostic aids

[PATCH v2 0/8] xen/events: bug fixes and some diagnostic aids

[Juergen Gross]

The first four patches are fixes for XSA-332. The avoid WARN splats
and a performance issue with interdomain events.

Patches 5 and 6 are some additions to event handling in order to add
some per pv-device statistics to sysfs and the ability to have a per
backend device spurious event delay control.

Patches 7 and 8 are minor fixes I had lying around.

Juergen Gross (8):
  xen/events: reset affinity of 2-level event when tearing it down
  xen/events: don't unmask an event channel when an eoi is pending
  xen/events: avoid handling the same event on two cpus at the same time
  xen/netback: fix spurious event detection for common event case
  xen/events: link interdomain events to associated xenbus device
  xen/events: add per-xenbus device event statistics and settings
  xen/evtchn: use smp barriers for user event ring
  xen/evtchn: use READ/WRITE_ONCE() for accessing ring indices

 .../ABI/testing/sysfs-devices-xenbus          |  41 ++++
 drivers/block/xen-blkback/xenbus.c            |   2 +-
 drivers/net/xen-netback/interface.c           |  24 ++-
 drivers/xen/events/events_2l.c                |  22 +-
 drivers/xen/events/events_base.c              | 190 ++++++++++++++----
 drivers/xen/events/events_fifo.c              |   7 -
 drivers/xen/events/events_internal.h          |  14 +-
 drivers/xen/evtchn.c                          |  29 ++-
 drivers/xen/pvcalls-back.c                    |   4 +-
 drivers/xen/xen-pciback/xenbus.c              |   2 +-
 drivers/xen/xen-scsiback.c                    |   2 +-
 drivers/xen/xenbus/xenbus_probe.c             |  66 ++++++
 include/xen/events.h                          |   7 +-
 include/xen/xenbus.h                          |   7 +
 14 files changed, 323 insertions(+), 94 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-xenbus

-- 
2.26.2

[PATCH v2 4/8] xen/netback: fix spurious event detection for common event case

[Juergen Gross]

In case of a common event for rx and tx queue the event should be
regarded to be spurious if no rx and no tx requests are pending.

Unfortunately the condition for testing that is wrong causing to
decide a event being spurious if no rx OR no tx requests are
pending.

Fix that plus using local variables for rx/tx pending indicators in
order to split function calls and if condition.

Fixes: 23025393dbeb3b ("xen/netback: use lateeoi irq binding")
Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- new patch, fixing FreeBSD performance issue
---
 drivers/net/xen-netback/interface.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index acb786d8b1d8..e02a4fbb74de 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -162,13 +162,15 @@ irqreturn_t xenvif_interrupt(int irq, void *dev_id)
 {
 	struct xenvif_queue *queue = dev_id;
 	int old;
+	bool has_rx, has_tx;
 
 	old = atomic_fetch_or(NETBK_COMMON_EOI, &queue->eoi_pending);
 	WARN(old, "Interrupt while EOI pending\n");
 
-	/* Use bitwise or as we need to call both functions. */
-	if ((!xenvif_handle_tx_interrupt(queue) |
-	     !xenvif_handle_rx_interrupt(queue))) {
+	has_tx = xenvif_handle_tx_interrupt(queue);
+	has_rx = xenvif_handle_rx_interrupt(queue);
+
+	if (!has_rx && !has_tx) {
 		atomic_andnot(NETBK_COMMON_EOI, &queue->eoi_pending);
 		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
 	}
-- 
2.26.2

[PATCH v2 5/8] xen/events: link interdomain events to associated xenbus device

[Juergen Gross]

In order to support the possibility of per-device event channel
settings (e.g. lateeoi spurious event thresholds) add a xenbus device
pointer to struct irq_info() and modify the related event channel
binding interfaces to take the pointer to the xenbus device as a
parameter instead of the domain id of the other side.

While at it remove the stale prototype of bind_evtchn_to_irq_lateeoi().

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
---
 drivers/block/xen-blkback/xenbus.c  |  2 +-
 drivers/net/xen-netback/interface.c | 16 +++++------
 drivers/xen/events/events_base.c    | 41 +++++++++++++++++------------
 drivers/xen/pvcalls-back.c          |  4 +--
 drivers/xen/xen-pciback/xenbus.c    |  2 +-
 drivers/xen/xen-scsiback.c          |  2 +-
 include/xen/events.h                |  7 ++---
 7 files changed, 41 insertions(+), 33 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 9860d4842f36..c2aaf690352c 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -245,7 +245,7 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
 	if (req_prod - rsp_prod > size)
 		goto fail;
 
-	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->domid,
+	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->be->dev,
 			evtchn, xen_blkif_be_int, 0, "blkif-backend", ring);
 	if (err < 0)
 		goto fail;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e02a4fbb74de..50a94e58c150 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -630,13 +630,13 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 			unsigned int evtchn)
 {
 	struct net_device *dev = vif->dev;
+	struct xenbus_device *xendev = xenvif_to_xenbus_device(vif);
 	void *addr;
 	struct xen_netif_ctrl_sring *shared;
 	RING_IDX rsp_prod, req_prod;
 	int err;
 
-	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
-				     &ring_ref, 1, &addr);
+	err = xenbus_map_ring_valloc(xendev, &ring_ref, 1, &addr);
 	if (err)
 		goto err;
 
@@ -650,7 +650,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl))
 		goto err_unmap;
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(vif->domid, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(xendev, evtchn);
 	if (err < 0)
 		goto err_unmap;
 
@@ -673,8 +673,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	vif->ctrl_irq = 0;
 
 err_unmap:
-	xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
-				vif->ctrl.sring);
+	xenbus_unmap_ring_vfree(xendev, vif->ctrl.sring);
 	vif->ctrl.sring = NULL;
 
 err:
@@ -719,6 +718,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 			unsigned int tx_evtchn,
 			unsigned int rx_evtchn)
 {
+	struct xenbus_device *dev = xenvif_to_xenbus_device(queue->vif);
 	struct task_struct *task;
 	int err;
 
@@ -755,7 +755,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 	if (tx_evtchn == rx_evtchn) {
 		/* feature-split-event-channels == 0 */
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
+			dev, tx_evtchn, xenvif_interrupt, 0,
 			queue->name, queue);
 		if (err < 0)
 			goto err;
@@ -766,7 +766,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 		snprintf(queue->tx_irq_name, sizeof(queue->tx_irq_name),
 			 "%s-tx", queue->name);
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
+			dev, tx_evtchn, xenvif_tx_interrupt, 0,
 			queue->tx_irq_name, queue);
 		if (err < 0)
 			goto err;
@@ -776,7 +776,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 		snprintf(queue->rx_irq_name, sizeof(queue->rx_irq_name),
 			 "%s-rx", queue->name);
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
+			dev, rx_evtchn, xenvif_rx_interrupt, 0,
 			queue->rx_irq_name, queue);
 		if (err < 0)
 			goto err;
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index f7e22330dcef..a5cce4c626c2 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -63,6 +63,7 @@
 #include <xen/interface/physdev.h>
 #include <xen/interface/sched.h>
 #include <xen/interface/vcpu.h>
+#include <xen/xenbus.h>
 #include <asm/hw_irq.h>
 
 #include "events_internal.h"
@@ -121,6 +122,7 @@ struct irq_info {
 			unsigned char flags;
 			uint16_t domid;
 		} pirq;
+		struct xenbus_device *interdomain;
 	} u;
 };
 
@@ -322,11 +324,16 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
-				     evtchn_port_t evtchn)
+				     evtchn_port_t evtchn,
+				     struct xenbus_device *dev)
 {
 	struct irq_info *info = info_for_irq(irq);
+	int ret;
 
-	return xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
+	ret = xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
+	info->u.interdomain = dev;
+
+	return ret;
 }
 
 static int xen_irq_info_ipi_setup(unsigned cpu,
@@ -1158,7 +1165,8 @@ int xen_pirq_from_irq(unsigned irq)
 }
 EXPORT_SYMBOL_GPL(xen_pirq_from_irq);
 
-static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
+static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip,
+				   struct xenbus_device *dev)
 {
 	int irq;
 	int ret;
@@ -1178,7 +1186,7 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 		irq_set_chip_and_handler_name(irq, chip,
 					      handle_edge_irq, "event");
 
-		ret = xen_irq_info_evtchn_setup(irq, evtchn);
+		ret = xen_irq_info_evtchn_setup(irq, evtchn, dev);
 		if (ret < 0) {
 			__unbind_from_irq(irq);
 			irq = ret;
@@ -1205,7 +1213,7 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 
 int bind_evtchn_to_irq(evtchn_port_t evtchn)
 {
-	return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip);
+	return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip, NULL);
 }
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
 
@@ -1254,27 +1262,27 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 	return irq;
 }
 
-static int bind_interdomain_evtchn_to_irq_chip(unsigned int remote_domain,
+static int bind_interdomain_evtchn_to_irq_chip(struct xenbus_device *dev,
 					       evtchn_port_t remote_port,
 					       struct irq_chip *chip)
 {
 	struct evtchn_bind_interdomain bind_interdomain;
 	int err;
 
-	bind_interdomain.remote_dom  = remote_domain;
+	bind_interdomain.remote_dom  = dev->otherend_id;
 	bind_interdomain.remote_port = remote_port;
 
 	err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
 					  &bind_interdomain);
 
 	return err ? : bind_evtchn_to_irq_chip(bind_interdomain.local_port,
-					       chip);
+					       chip, dev);
 }
 
-int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
 					   evtchn_port_t remote_port)
 {
-	return bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
+	return bind_interdomain_evtchn_to_irq_chip(dev, remote_port,
 						   &xen_lateeoi_chip);
 }
 EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
@@ -1387,7 +1395,7 @@ static int bind_evtchn_to_irqhandler_chip(evtchn_port_t evtchn,
 {
 	int irq, retval;
 
-	irq = bind_evtchn_to_irq_chip(evtchn, chip);
+	irq = bind_evtchn_to_irq_chip(evtchn, chip, NULL);
 	if (irq < 0)
 		return irq;
 	retval = request_irq(irq, handler, irqflags, devname, dev_id);
@@ -1422,14 +1430,13 @@ int bind_evtchn_to_irqhandler_lateeoi(evtchn_port_t evtchn,
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler_lateeoi);
 
 static int bind_interdomain_evtchn_to_irqhandler_chip(
-		unsigned int remote_domain, evtchn_port_t remote_port,
+		struct xenbus_device *dev, evtchn_port_t remote_port,
 		irq_handler_t handler, unsigned long irqflags,
 		const char *devname, void *dev_id, struct irq_chip *chip)
 {
 	int irq, retval;
 
-	irq = bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
-						  chip);
+	irq = bind_interdomain_evtchn_to_irq_chip(dev, remote_port, chip);
 	if (irq < 0)
 		return irq;
 
@@ -1442,14 +1449,14 @@ static int bind_interdomain_evtchn_to_irqhandler_chip(
 	return irq;
 }
 
-int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irqhandler_lateeoi(struct xenbus_device *dev,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
 						  unsigned long irqflags,
 						  const char *devname,
 						  void *dev_id)
 {
-	return bind_interdomain_evtchn_to_irqhandler_chip(remote_domain,
+	return bind_interdomain_evtchn_to_irqhandler_chip(dev,
 				remote_port, handler, irqflags, devname,
 				dev_id, &xen_lateeoi_chip);
 }
@@ -1723,7 +1730,7 @@ void rebind_evtchn_irq(evtchn_port_t evtchn, int irq)
 	   so there should be a proper type */
 	BUG_ON(info->type == IRQT_UNBOUND);
 
-	(void)xen_irq_info_evtchn_setup(irq, evtchn);
+	(void)xen_irq_info_evtchn_setup(irq, evtchn, NULL);
 
 	mutex_unlock(&irq_mapping_update_lock);
 
diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index a7d293fa8d14..b47fd8435061 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -348,7 +348,7 @@ static struct sock_mapping *pvcalls_new_active_socket(
 	map->bytes = page;
 
 	ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			fedata->dev->otherend_id, evtchn,
+			fedata->dev, evtchn,
 			pvcalls_back_conn_event, 0, "pvcalls-backend", map);
 	if (ret < 0)
 		goto out;
@@ -948,7 +948,7 @@ static int backend_connect(struct xenbus_device *dev)
 		goto error;
 	}
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(dev->otherend_id, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn);
 	if (err < 0)
 		goto error;
 	fedata->irq = err;
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index e7c692cfb2cf..5188f02e75fb 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -124,7 +124,7 @@ static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
 	pdev->sh_info = vaddr;
 
 	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-		pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
+		pdev->xdev, remote_evtchn, xen_pcibk_handle_event,
 		0, DRV_NAME, pdev);
 	if (err < 0) {
 		xenbus_dev_fatal(pdev->xdev, err,
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 862162dca33c..8b59897b2df9 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -799,7 +799,7 @@ static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 	sring = (struct vscsiif_sring *)area;
 	BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(info->domid, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(info->dev, evtchn);
 	if (err < 0)
 		goto unmap_page;
 
diff --git a/include/xen/events.h b/include/xen/events.h
index 8ec418e30c7f..c204262d9fc2 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -12,10 +12,11 @@
 #include <asm/xen/hypercall.h>
 #include <asm/xen/events.h>
 
+struct xenbus_device;
+
 unsigned xen_evtchn_nr_channels(void);
 
 int bind_evtchn_to_irq(evtchn_port_t evtchn);
-int bind_evtchn_to_irq_lateeoi(evtchn_port_t evtchn);
 int bind_evtchn_to_irqhandler(evtchn_port_t evtchn,
 			      irq_handler_t handler,
 			      unsigned long irqflags, const char *devname,
@@ -35,9 +36,9 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
 			   unsigned long irqflags,
 			   const char *devname,
 			   void *dev_id);
-int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
 					   evtchn_port_t remote_port);
-int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irqhandler_lateeoi(struct xenbus_device *dev,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
 						  unsigned long irqflags,
-- 
2.26.2

Re: [PATCH v2 4/8] xen/netback: fix spurious event detection for common event case

[Jan Beulich]

On 11.02.2021 11:16, Juergen Gross wrote:
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -162,13 +162,15 @@ irqreturn_t xenvif_interrupt(int irq, void *dev_id)
>  {
>  	struct xenvif_queue *queue = dev_id;
>  	int old;
> +	bool has_rx, has_tx;
>  
>  	old = atomic_fetch_or(NETBK_COMMON_EOI, &queue->eoi_pending);
>  	WARN(old, "Interrupt while EOI pending\n");
>  
> -	/* Use bitwise or as we need to call both functions. */
> -	if ((!xenvif_handle_tx_interrupt(queue) |
> -	     !xenvif_handle_rx_interrupt(queue))) {
> +	has_tx = xenvif_handle_tx_interrupt(queue);
> +	has_rx = xenvif_handle_rx_interrupt(queue);
> +
> +	if (!has_rx && !has_tx) {
>  		atomic_andnot(NETBK_COMMON_EOI, &queue->eoi_pending);
>  		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
>  	}
> 

Ah yes, what was originally meant really was

	if (!(xenvif_handle_tx_interrupt(queue) |
	      xenvif_handle_rx_interrupt(queue))) {

(also hinted at by the otherwise pointless inner parentheses),
which you simply write in an alternative way.

Reviewed-by: Jan Beulich <jbeulich@suse.com>

Jan

RE: [PATCH v2 4/8] xen/netback: fix spurious event detection for common event case

[Paul Durrant]

> -----Original Message-----
> From: Juergen Gross <jgross@suse.com>
> Sent: 11 February 2021 10:16
> To: xen-devel@lists.xenproject.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: Juergen Gross <jgross@suse.com>; Wei Liu <wei.liu@kernel.org>; Paul Durrant <paul@xen.org>; David
> S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>
> Subject: [PATCH v2 4/8] xen/netback: fix spurious event detection for common event case
> 
> In case of a common event for rx and tx queue the event should be
> regarded to be spurious if no rx and no tx requests are pending.
> 
> Unfortunately the condition for testing that is wrong causing to
> decide a event being spurious if no rx OR no tx requests are
> pending.
> 
> Fix that plus using local variables for rx/tx pending indicators in
> order to split function calls and if condition.
> 

Definitely neater.

> Fixes: 23025393dbeb3b ("xen/netback: use lateeoi irq binding")
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Paul Durrant <paul@xen.org>

RE: [PATCH v2 5/8] xen/events: link interdomain events to associated xenbus device

[Paul Durrant]

> -----Original Message-----
> From: Juergen Gross <jgross@suse.com>
> Sent: 11 February 2021 10:16
> To: xen-devel@lists.xenproject.org; linux-block@vger.kernel.org; linux-kernel@vger.kernel.org;
> netdev@vger.kernel.org; linux-scsi@vger.kernel.org
> Cc: Juergen Gross <jgross@suse.com>; Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>; Roger Pau Monné
> <roger.pau@citrix.com>; Jens Axboe <axboe@kernel.dk>; Wei Liu <wei.liu@kernel.org>; Paul Durrant
> <paul@xen.org>; David S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Boris
> Ostrovsky <boris.ostrovsky@oracle.com>; Stefano Stabellini <sstabellini@kernel.org>
> Subject: [PATCH v2 5/8] xen/events: link interdomain events to associated xenbus device
> 
> In order to support the possibility of per-device event channel
> settings (e.g. lateeoi spurious event thresholds) add a xenbus device
> pointer to struct irq_info() and modify the related event channel
> binding interfaces to take the pointer to the xenbus device as a
> parameter instead of the domain id of the other side.
> 
> While at it remove the stale prototype of bind_evtchn_to_irq_lateeoi().
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Reviewed-by: Wei Liu <wei.liu@kernel.org>

Reviewed-by: Paul Durrant <paul@xen.org>

Re: [PATCH v2 4/8] xen/netback: fix spurious event detection for common event case

[Wei Liu]

On Thu, Feb 11, 2021 at 11:16:12AM +0100, Juergen Gross wrote:
> In case of a common event for rx and tx queue the event should be
> regarded to be spurious if no rx and no tx requests are pending.
> 
> Unfortunately the condition for testing that is wrong causing to
> decide a event being spurious if no rx OR no tx requests are
> pending.
> 
> Fix that plus using local variables for rx/tx pending indicators in
> order to split function calls and if condition.
> 
> Fixes: 23025393dbeb3b ("xen/netback: use lateeoi irq binding")
> Signed-off-by: Juergen Gross <jgross@suse.com>

Reviewed-by: Wei Liu <wl@xen.org>