From d696c940cb749ec79f92f2c9888fb0cd73259197 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@suse.com>
Date: Thu, 11 Feb 2021 09:37:21 +0100
Patch-mainline: Queued in subsystem maintainer repository; https://lkml.org/lkml/2021/2/11/224
References: bsc#1182175
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
Git-commit: a3daf3d39132b405781be8d9ede0c449b244b64e
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.

Fixes: 23025393dbeb3b ("xen/netback: use lateeoi irq binding")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Wei Liu <wl@xen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 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