kernel/smp: Distinguish CPUSet::GetBit from GetBitAtomic.

I checked all invocations of GetBit; as far as I can tell,
only the two adjusted here in smp.cpp are done while the Set
may be concurrently modified, and even then I don't know
that they really need to be atomics, anyway.

headers/private/kernel/smp.h

@@ -54,6 +54,7 @@ public:
 	inline	void		ClearBitAtomic(int32 cpu);
 
 	inline	bool		GetBit(int32 cpu) const;
+	inline	bool		GetBitAtomic(int32 cpu) const;
 
 	inline	bool		Matches(const CPUSet& mask) const;
 	inline	CPUSet		And(const CPUSet& mask) const;
@@ -161,6 +162,14 @@ CPUSet::ClearBitAtomic(int32 cpu)
 
 inline bool
 CPUSet::GetBit(int32 cpu) const
+{
+	int32* element = (int32*)&fBitmap[cpu / kArrayBits];
+	return ((uint32)*element & (1u << (cpu % kArrayBits))) != 0;
+}
+
+
+inline bool
+CPUSet::GetBitAtomic(int32 cpu) const
 {
 	int32* element = (int32*)&fBitmap[cpu / kArrayBits];
 	return ((uint32)atomic_get(element) & (1u << (cpu % kArrayBits))) != 0;

src/system/kernel/smp.cpp

@@ -760,7 +760,7 @@ check_for_message(int currentCPU, mailbox_source& sourceMailbox)
 
 		msg = sBroadcastMessages;
 		while (msg != NULL) {
-			if (!msg->proc_bitmap.GetBit(currentCPU)) {
+			if (!msg->proc_bitmap.GetBitAtomic(currentCPU)) {
 				// we have handled this one already
 				msg = msg->next;
 				continue;
@@ -1260,7 +1260,7 @@ smp_trap_non_boot_cpus(int32 cpu, uint32* rendezVous)
 	smp_cpu_rendezvous(rendezVous);
 
 	while (sBootCPUSpin == 0) {
-		if (sEarlyCPUCallSet.GetBit(cpu))
+		if (sEarlyCPUCallSet.GetBitAtomic(cpu))
 			process_early_cpu_call(cpu);
 
 		cpu_pause();