Patch-mainline: v6.7-rc2
Git-commit: 47d970204054f859f35a2237baa75c2d84fcf436
References: git-fixes
From: Juergen Gross <jgross@suse.com>
Date: Mon, 25 Sep 2023 17:54:13 +0200
Subject: [PATCH] xen/events: fix delayed eoi list handling

When delaying eoi handling of events, the related elements are queued
into the percpu lateeoi list. In case the list isn't empty, the
elements should be sorted by the time when eoi handling is to happen.

Unfortunately a new element will never be queued at the start of the
list, even if it has a handling time lower than all other list
elements.

Fix that by handling that case the same way as for an empty list.

Fixes: e99502f76271 ("xen/events: defer eoi in case of excessive number of events")
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/events/events_base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 237e6b884f72..cd33a418344a 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -604,7 +604,9 @@ static void lateeoi_list_add(struct irq_info *info)
 
 	spin_lock_irqsave(&eoi->eoi_list_lock, flags);
 
-	if (list_empty(&eoi->eoi_list)) {
+	elem = list_first_entry_or_null(&eoi->eoi_list, struct irq_info,
+					eoi_list);
+	if (!elem || info->eoi_time < elem->eoi_time) {
 		list_add(&info->eoi_list, &eoi->eoi_list);
 		mod_delayed_work_on(info->eoi_cpu, system_wq,
 				    &eoi->delayed, delay);
-- 
2.35.3