mm/resource: Use resource_overlaps() to simplify region_intersects()

The three checks in region_intersects() are basically an open-coded version
of resource_overlaps() - so use the real thing.

Also fix typos in comments while at it.
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Yuan Yao <yuan.yao@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: bhelgaas@google.com
Cc: bp@suse.de
Cc: dan.j.williams@intel.com
Cc: jack@suse.cz
Cc: rdunlap@infradead.org
Cc: tiwai@suse.de
Link: http://lkml.kernel.org/r/20190305083432.23675-1-richardw.yang@linux.intel.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/iomem.c

@@ -55,7 +55,7 @@ static void *try_ram_remap(resource_size_t offset, size_t size,
  *
  * MEMREMAP_WB - matches the default mapping for System RAM on
  * the architecture.  This is usually a read-allocate write-back cache.
- * Morever, if MEMREMAP_WB is specified and the requested remap region is RAM
+ * Moreover, if MEMREMAP_WB is specified and the requested remap region is RAM
  * memremap() will bypass establishing a new mapping and instead return
  * a pointer into the direct map.
  *
@@ -86,7 +86,7 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 	/* Try all mapping types requested until one returns non-NULL */
 	if (flags & MEMREMAP_WB) {
 		/*
-		 * MEMREMAP_WB is special in that it can be satisifed
+		 * MEMREMAP_WB is special in that it can be satisfied
 		 * from the direct map.  Some archs depend on the
 		 * capability of memremap() to autodetect cases where
 		 * the requested range is potentially in System RAM.

kernel/resource.c

@@ -520,21 +520,20 @@ EXPORT_SYMBOL_GPL(page_is_ram);
 int region_intersects(resource_size_t start, size_t size, unsigned long flags,
 		      unsigned long desc)
 {
-	resource_size_t end = start + size - 1;
+	struct resource res;
 	int type = 0; int other = 0;
 	struct resource *p;
 
+	res.start = start;
+	res.end = start + size - 1;
+
 	read_lock(&resource_lock);
 	for (p = iomem_resource.child; p ; p = p->sibling) {
 		bool is_type = (((p->flags & flags) == flags) &&
 				((desc == IORES_DESC_NONE) ||
 				 (desc == p->desc)));
 
-		if (start >= p->start && start <= p->end)
-			is_type ? type++ : other++;
-		if (end >= p->start && end <= p->end)
-			is_type ? type++ : other++;
-		if (p->start >= start && p->end <= end)
+		if (resource_overlaps(p, &res))
 			is_type ? type++ : other++;
 	}
 	read_unlock(&resource_lock);