x86/mm: Clean up the TLB flushing code

The

	if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)

line of code is not exactly the easiest to audit, especially when
it ends up at two different indentation levels.  This eliminates
one of the the copy-n-paste versions.  It also gives us a unified
exit point for each path through this function.  We need this in
a minute for our tracepoint.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/r/20140731154054.44F1CDDC@viggo.jf.intel.com
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

arch/x86/mm/tlb.c

@@ -161,23 +161,24 @@ void flush_tlb_current_task(void)
 void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 				unsigned long end, unsigned long vmflag)
 {
+	bool need_flush_others_all = true;
 	unsigned long addr;
 	unsigned act_entries, tlb_entries = 0;
 	unsigned long nr_base_pages;
 
 	preempt_disable();
 	if (current->active_mm != mm)
-		goto flush_all;
+		goto out;
 
 	if (!current->mm) {
 		leave_mm(smp_processor_id());
-		goto flush_all;
+		goto out;
 	}
 
 	if (end == TLB_FLUSH_ALL || tlb_flushall_shift == -1
 					|| vmflag & VM_HUGETLB) {
 		local_flush_tlb();
-		goto flush_all;
+		goto out;
 	}
 
 	/* In modern CPU, last level tlb used for both data/ins */
@@ -196,22 +197,20 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 		count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
 		local_flush_tlb();
 	} else {
+		need_flush_others_all = false;
 		/* flush range by one by one 'invlpg' */
 		for (addr = start; addr < end;	addr += PAGE_SIZE) {
 			count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
 			__flush_tlb_single(addr);
 		}
-
-		if (cpumask_any_but(mm_cpumask(mm),
-				smp_processor_id()) < nr_cpu_ids)
-			flush_tlb_others(mm_cpumask(mm), mm, start, end);
-		preempt_enable();
-		return;
 	}
-
-flush_all:
+out:
+	if (need_flush_others_all) {
+		start = 0UL;
+		end = TLB_FLUSH_ALL;
+	}
 	if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
-		flush_tlb_others(mm_cpumask(mm), mm, 0UL, TLB_FLUSH_ALL);
+		flush_tlb_others(mm_cpumask(mm), mm, start, end);
 	preempt_enable();
 }