From f14f2603820e46b1946d8f96eee10c99690aea82 Mon Sep 17 00:00:00 2001
From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Sun, 29 Jun 2025 13:13:34 +0200
Subject: [PATCH] util: fix endless loop in get_backoff_delta_msec

If current time t is already past tend, the while loop in
get_backoff_delta_msec never ends.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Link: https://github.com/kmod-project/kmod/pull/377
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
---
 shared/util.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/shared/util.c b/shared/util.c
index 17f6fd1..27e9130 100644
--- a/shared/util.c
+++ b/shared/util.c
@@ -504,16 +504,23 @@ unsigned long long get_backoff_delta_msec(unsigned long long t0,
 
 	t = now_msec();
 
-	if (!*delta)
-		*delta = 1;
-	else
-		*delta <<= 1;
+	if (tend <= t) {
+		/* Timeout already reached */
+		*delta = 0;
+	} else {
+		const unsigned long long limit = tend - t;
+
+		if (!*delta)
+			*delta = 1;
+		else
+			*delta <<= 1;
 
-	while (t + *delta > tend)
-		*delta >>= 1;
+		while (*delta > limit)
+			*delta >>= 1;
 
-	if (!*delta && tend > t)
-		*delta = tend - t;
+		if (!*delta)
+			*delta = limit;
+	}
 
 	return t + *delta;
 }
-- 
2.43.0