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[PATCH v2] timer: fix NR_CPUS=1 build with gcc13
- To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 14 Sep 2023 16:32:01 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>
- Delivery-date: Thu, 14 Sep 2023 14:32:42 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
Gcc13 apparently infers from "if ( old_cpu < new_cpu )" that "new_cpu"
is >= 1, and then (on x86) complains about "per_cpu(timers, new_cpu)"
exceeding __per_cpu_offset[]'s bounds (being an array of 1 in such a
configuration). Make the code conditional upon there being at least 2
CPUs configured (otherwise there simply is nothing to migrate [to]).
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2: Warn if it looks like an actual migration was (bogusly) requested.
--- a/xen/common/timer.c
+++ b/xen/common/timer.c
@@ -357,6 +357,7 @@ bool timer_expires_before(struct timer *
void migrate_timer(struct timer *timer, unsigned int new_cpu)
{
unsigned int old_cpu;
+#if CONFIG_NR_CPUS > 1
bool_t active;
unsigned long flags;
@@ -404,6 +405,11 @@ void migrate_timer(struct timer *timer,
spin_unlock(&per_cpu(timers, old_cpu).lock);
spin_unlock_irqrestore(&per_cpu(timers, new_cpu).lock, flags);
+#else /* CONFIG_NR_CPUS == 1 */
+ old_cpu = read_atomic(&timer->cpu);
+ if ( old_cpu != TIMER_CPU_status_killed )
+ WARN_ON(new_cpu != old_cpu);
+#endif /* CONFIG_NR_CPUS */
}
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