base-hw: always use 'unsigned' for priorities

At some points in the code, 'signed' was used instead of the more appropriate
'unsigned' type.

Ref #4217

repos/base-hw/src/core/kernel/cpu_scheduler.cc

@@ -34,7 +34,7 @@ void Cpu_scheduler::_reset_claims(unsigned const p)
 void Cpu_scheduler::_next_round()
 {
 	_residual = _quota;
-	_for_each_prio([&] (unsigned const p) { _reset_claims(p); });
+	_for_each_prio([&] (Cpu_priority const p, bool &) { _reset_claims(p); });
 }
 
 
@@ -90,21 +90,23 @@ void Cpu_scheduler::_head_filled(unsigned const r)
 
 bool Cpu_scheduler::_claim_for_head()
 {
-	for (signed p = Prio::MAX; p > Prio::MIN - 1; p--) {
+	bool result { false };
+	_for_each_prio([&] (Cpu_priority const p, bool &cancel_for_each_prio) {
 		Double_list_item<Cpu_share> *const item { _rcl[p].head() };
 
 		if (!item)
-			continue;
+			return;
 
 		Cpu_share &share { item->payload() };
 
 		if (!share._claim)
-			continue;
+			return;
 
 		_set_head(share, share._claim, 1);
-		return 1;
+		result = true;
-	}
+		cancel_for_each_prio = true;
-	return 0;
+	});
+	return result;
 }
 
 

repos/base-hw/src/core/kernel/cpu_scheduler.h

@@ -47,27 +47,28 @@ class Kernel::Cpu_priority
 
 	public:
 
-		enum {
+		static constexpr unsigned min() { return 0; }
-			MIN = 0,
+		static constexpr unsigned max() { return cpu_priorities - 1; }
-			MAX = cpu_priorities - 1,
-		};
 
 		/**
 		 * Construct priority with value 'v'
 		 */
-		Cpu_priority(signed const v) : _value(Genode::min(v, MAX)) { }
+		Cpu_priority(unsigned const v)
+		:
+			_value { Genode::min(v, max()) }
+		{ }
 
 		/*
 		 * Standard operators
 		 */
 
-		Cpu_priority &operator =(signed const v)
+		Cpu_priority &operator =(unsigned const v)
 		{
-			_value = Genode::min(v, MAX);
+			_value = Genode::min(v, max());
 			return *this;
 		}
 
-		operator signed() const { return _value; }
+		operator unsigned() const { return _value; }
 };
 
 
@@ -79,7 +80,7 @@ class Kernel::Cpu_share
 
 		Double_list_item<Cpu_share> _fill_item  { *this };
 		Double_list_item<Cpu_share> _claim_item { *this };
-		signed const                _prio;
+		Cpu_priority          const _prio;
 		unsigned                    _quota;
 		unsigned                    _claim;
 		unsigned                    _fill       { 0 };
@@ -93,7 +94,7 @@ class Kernel::Cpu_share
 		 * \param p  claimed priority
 		 * \param q  claimed quota
 		 */
-		Cpu_share(signed const p, unsigned const q)
+		Cpu_share(Cpu_priority const p, unsigned const q)
 		: _prio(p), _quota(q), _claim(q) { }
 
 		/*
@@ -111,8 +112,8 @@ class Kernel::Cpu_scheduler
 		typedef Cpu_share    Share;
 		typedef Cpu_priority Prio;
 
-		Double_list<Cpu_share>  _rcl[Prio::MAX + 1]; /* ready claims */
+		Double_list<Cpu_share>  _rcl[Prio::max() + 1]; /* ready claims */
-		Double_list<Cpu_share>  _ucl[Prio::MAX + 1]; /* unready claims */
+		Double_list<Cpu_share>  _ucl[Prio::max() + 1]; /* unready claims */
 		Double_list<Cpu_share>  _fills { };          /* ready fills */
 		Share                  &_idle;
 		Share                  *_head = nullptr;
@@ -125,8 +126,15 @@ class Kernel::Cpu_scheduler
 		bool                    _need_to_schedule { true };
 		time_t                  _last_time { 0 };
 
-		template <typename F> void _for_each_prio(F f) {
+		template <typename F> void _for_each_prio(F f)
-			for (signed p = Prio::MAX; p > Prio::MIN - 1; p--) { f(p); } }
+		{
+			bool cancel_for_each_prio { false };
+			for (unsigned p = Prio::max(); p != Prio::min() - 1; p--) {
+				f(p, cancel_for_each_prio);
+				if (cancel_for_each_prio)
+					return;
+			}
+		}
 
 		static void _reset(Cpu_share &share);
 

repos/base-hw/src/core/kernel/thread.h

@@ -293,7 +293,7 @@ class Kernel::Thread : private Kernel::Object, public Cpu_job, private Timeout
 		 * \param label  debugging label
 		 */
 		Thread(char const * const label)
-		: Thread(Cpu_priority::MIN, 0, label, true) { }
+		: Thread(Cpu_priority::min(), 0, label, true) { }
 
 		~Thread();
 

repos/base-hw/src/core/platform_thread.h

@@ -89,7 +89,7 @@ class Genode::Platform_thread : Noncopyable
 
 		unsigned _scale_priority(unsigned virt_prio)
 		{
-			return Cpu_session::scale_priority(Kernel::Cpu_priority::MAX,
+			return Cpu_session::scale_priority(Kernel::Cpu_priority::max(),
 			                                   virt_prio);
 		}
 

repos/base-hw/src/core/spec/arm_v7/trustzone/kernel/vm.cc

@@ -26,7 +26,7 @@ Kernel::Vm::Vm(unsigned,
                Identity               & id)
 :
 	Kernel::Object { *this },
-	Cpu_job(Cpu_priority::MIN, 0),
+	Cpu_job(Cpu_priority::min(), 0),
 	_state(state),
 	_context(context),
 	_id(id),

repos/base-hw/src/core/spec/arm_v7/virtualization/kernel/vm.cc

@@ -140,7 +140,7 @@ Kernel::Vm::Vm(unsigned                 cpu,
                Identity               & id)
 :
 	Kernel::Object { *this },
-	Cpu_job(Cpu_priority::MIN, 0),
+	Cpu_job(Cpu_priority::min(), 0),
 	_state(state),
 	_context(context),
 	_id(id),

repos/base-hw/src/core/spec/arm_v8/virtualization/kernel/vm.cc

@@ -115,7 +115,7 @@ Vm::Vm(unsigned                 cpu,
        Identity               & id)
 :
 	Kernel::Object { *this },
-	Cpu_job(Cpu_priority::MIN, 0),
+	Cpu_job(Cpu_priority::min(), 0),
 	_state(state),
 	_context(context),
 	_id(id),