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[PATCH] xen/sched: resolve MISRA R18.3 pointer comparison
- To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>
- Date: Tue, 10 Nov 2026 09:59:14 +0000
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- Cc: Dmytro Prokopchuk1 <dmytro_prokopchuk1@xxxxxxxx>, Dario Faggioli <dfaggioli@xxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, George Dunlap <gwd@xxxxxxxxxxxxxx>
- Delivery-date: Tue, 10 Nov 2026 09:59:20 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Thread-index: AQHdcPokuddABcs0aEGWzDRXWlu8ug==
- Thread-topic: [PATCH] xen/sched: resolve MISRA R18.3 pointer comparison
MISRA C Rule 18.3 states: "The relational operators >, >=, < and <=
shall not be applied to objects of pointer type except where they
point into the same object".
sched_spin_lock_double() takes the lock at the lower address first.
The two spinlock_t pointers are not required to point into the same
object, so compare the addresses as integers.
unsigned long is the right integer type here. It is pointer-sized on
every architecture Xen supports, so the cast keeps the full address,
and an unsigned comparison still means "lower address first". A signed
long would interpret an address with the high bit set as negative, so
the order would no longer follow that rule.
No functional change.
Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
---
Test CI pipeline:
https://gitlab.com/xen-project/people/dimaprkp4k/xen/-/pipelines/3048801945
---
xen/common/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index 88ae40f954..10b6eecccd 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -377,7 +377,7 @@ static always_inline void sched_spin_lock_double(
{
*flags = _spin_lock_irqsave(lock1);
}
- else if ( lock1 < lock2 )
+ else if ( (unsigned long)lock1 < (unsigned long)lock2 )
{
*flags = _spin_lock_irqsave(lock1);
_spin_lock(lock2);
--
2.43.0
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