domctl: correct return value of XEN_DOMCTL_[gs]etvcpuaffinity

cpumask_to_xenctl_bitmap() may return errors. Clearing the error indicator
of an earlier such call by a (successful) later call is misleading the
caller. For "set", keep setting soft affinity if the hard affinity copy-
back fails; only accumulate respective errors.

While fiddling with return values, also drop a redundant clearing of
"ret". This eliminates a Misra C:2012 rule 2.2 ("There shall be no dead
code") violation.

Fixes: 6e4ecc6d58 ("sched: DOMCTL_*vcpuaffinity works with hard and soft affinity")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 6a21252a74
master date: 2026-06-18 10:02:34 +0200

xen/common/sched/core.c

@@ -1675,7 +1675,7 @@ int vcpu_affinity_domctl(struct domain *d, uint32_t cmd,
 {
     struct vcpu *v;
     const struct sched_unit *unit;
-    int ret = 0;
+    int ret = 0, hret = 0;
 
     if ( vcpuaff->vcpu >= d->max_vcpus )
         return -EINVAL;
@@ -1713,19 +1713,17 @@ int vcpu_affinity_domctl(struct domain *d, uint32_t cmd,
         if ( vcpuaff->flags & XEN_VCPUAFFINITY_FORCE )
             vcpu_temporary_affinity(v, NR_CPUS, VCPU_AFFINITY_OVERRIDE);
 
-        ret = 0;
-
         /*
          * We both set a new affinity and report back to the caller what
          * the scheduler will be effectively using.
          */
         if ( vcpuaff->flags & XEN_VCPUAFFINITY_HARD )
         {
-            ret = xenctl_bitmap_to_bitmap(cpumask_bits(new_affinity),
-                                          &vcpuaff->cpumap_hard, nr_cpu_ids);
-            if ( !ret )
-                ret = vcpu_set_hard_affinity(v, new_affinity);
-            if ( ret )
+            hret = xenctl_bitmap_to_bitmap(cpumask_bits(new_affinity),
+                                           &vcpuaff->cpumap_hard, nr_cpu_ids);
+            if ( !hret )
+                hret = vcpu_set_hard_affinity(v, new_affinity);
+            if ( hret )
                 goto setvcpuaffinity_out;
 
             /*
@@ -1733,7 +1731,7 @@ int vcpu_affinity_domctl(struct domain *d, uint32_t cmd,
              * cpupool's online mask and the new hard affinity.
              */
             cpumask_and(new_affinity, online, unit->cpu_hard_affinity);
-            ret = cpumask_to_xenctl_bitmap(&vcpuaff->cpumap_hard, new_affinity);
+            hret = cpumask_to_xenctl_bitmap(&vcpuaff->cpumap_hard, new_affinity);
         }
         if ( vcpuaff->flags & XEN_VCPUAFFINITY_SOFT )
         {
@@ -1770,14 +1768,14 @@ int vcpu_affinity_domctl(struct domain *d, uint32_t cmd,
     else
     {
         if ( vcpuaff->flags & XEN_VCPUAFFINITY_HARD )
-            ret = cpumask_to_xenctl_bitmap(&vcpuaff->cpumap_hard,
-                                           unit->cpu_hard_affinity);
+            hret = cpumask_to_xenctl_bitmap(&vcpuaff->cpumap_hard,
+                                            unit->cpu_hard_affinity);
         if ( vcpuaff->flags & XEN_VCPUAFFINITY_SOFT )
             ret = cpumask_to_xenctl_bitmap(&vcpuaff->cpumap_soft,
                                            unit->cpu_soft_affinity);
     }
 
-    return ret;
+    return hret ?: ret;
 }
 
 bool alloc_affinity_masks(struct affinity_masks *affinity)