[PATCH 3/4] sched/core: avoid use of "current" in initializer lists

[Jan Beulich <jbeulich@xxxxxxxx>]

TRACE_TIME() uses an initializer list and hence is covered by Misra C:2012
rule 13.1 ("Initializer lists shall not contain persistent side effects").
Use intermediate variables to address this.

In vcpu_yield() take the opportunity to rename the existing variable which
better would have been used already before.

In do_sched_op() extend the scope of and rename an existing variable. Also
drop a pointless (and slightly malformed, style-wise) cast there, and
adjust to other one to by style conformant.

No functional change intended.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Note that the violations presently are reported only for Arm. Similar
issues would exist on x86 in Clang builds, afaict.

--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -1531,20 +1531,20 @@ static long do_poll(const struct sched_p
 /* Voluntarily yield the processor for this allocation. */
 long vcpu_yield(void)
 {
-    struct vcpu * v=current;
+    struct vcpu *curr = current;
     spinlock_t *lock;
 
     rcu_read_lock(&sched_res_rculock);
 
-    lock = unit_schedule_lock_irq(v->sched_unit);
-    sched_yield(vcpu_scheduler(v), v->sched_unit);
-    unit_schedule_unlock_irq(lock, v->sched_unit);
+    lock = unit_schedule_lock_irq(curr->sched_unit);
+    sched_yield(vcpu_scheduler(curr), curr->sched_unit);
+    unit_schedule_unlock_irq(lock, curr->sched_unit);
 
     rcu_read_unlock(&sched_res_rculock);
 
     SCHED_STAT_CRANK(vcpu_yield);
 
-    TRACE_TIME(TRC_SCHED_YIELD, current->domain->domain_id, current->vcpu_id);
+    TRACE_TIME(TRC_SCHED_YIELD, curr->domain->domain_id, curr->vcpu_id);
     raise_softirq(SCHEDULE_SOFTIRQ);
     return 0;
 }
@@ -1914,6 +1914,8 @@ typedef long ret_t;
 
 ret_t do_sched_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 {
+    const struct vcpu *curr = current;
+    struct domain *currd = curr->domain;
     ret_t ret = 0;
 
     switch ( cmd )
@@ -1938,9 +1940,9 @@ ret_t do_sched_op(int cmd, XEN_GUEST_HAN
         if ( copy_from_guest(&sched_shutdown, arg, 1) )
             break;
 
-        TRACE_TIME(TRC_SCHED_SHUTDOWN, current->domain->domain_id,
-                   current->vcpu_id, sched_shutdown.reason);
-        ret = domain_shutdown(current->domain, (u8)sched_shutdown.reason);
+        TRACE_TIME(TRC_SCHED_SHUTDOWN, currd->domain_id, curr->vcpu_id,
+                   sched_shutdown.reason);
+        ret = domain_shutdown(currd, sched_shutdown.reason);
 
         break;
     }
@@ -1948,19 +1950,18 @@ ret_t do_sched_op(int cmd, XEN_GUEST_HAN
     case SCHEDOP_shutdown_code:
     {
         struct sched_shutdown sched_shutdown;
-        struct domain *d = current->domain;
 
         ret = -EFAULT;
         if ( copy_from_guest(&sched_shutdown, arg, 1) )
             break;
 
-        TRACE_TIME(TRC_SCHED_SHUTDOWN_CODE, d->domain_id, current->vcpu_id,
+        TRACE_TIME(TRC_SCHED_SHUTDOWN_CODE, currd->domain_id, curr->vcpu_id,
                    sched_shutdown.reason);
 
-        spin_lock(&d->shutdown_lock);
-        if ( d->shutdown_code == SHUTDOWN_CODE_INVALID )
-            d->shutdown_code = (u8)sched_shutdown.reason;
-        spin_unlock(&d->shutdown_lock);
+        spin_lock(&currd->shutdown_lock);
+        if ( currd->shutdown_code == SHUTDOWN_CODE_INVALID )
+            currd->shutdown_code = (uint8_t)sched_shutdown.reason;
+        spin_unlock(&currd->shutdown_lock);
 
         ret = 0;
         break;