lib/rhashtable: simplify bucket_table_alloc()

As of ce91f6ee5b ("mm: kvmalloc does not fallback to vmalloc for
incompatible gfp flags") we can simplify the caller and trust kvzalloc()
to just do the right thing.  For the case of the GFP_ATOMIC context, we
can drop the __GFP_NORETRY flag for obvious reasons, and for the
__GFP_NOWARN case, however, it is changed such that the caller passes the
flag instead of making bucket_table_alloc() handle it.

This slightly changes the gfp flags passed on to nested_table_alloc() as
it will now also use GFP_ATOMIC | __GFP_NOWARN.  However, I consider this
a positive consequence as for the same reasons we want nowarn semantics in
bucket_table_alloc().

[[email protected]: commit id extended to 12 digits, line wraps updated]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Manfred Spraul <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

lib/rhashtable.c

@@ -174,10 +174,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 	int i;
 
 	size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
-	if (gfp != GFP_KERNEL)
-		tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
-	else
-		tbl = kvzalloc(size, gfp);
+	tbl = kvzalloc(size, gfp);
 
 	size = nbuckets;
 
@@ -450,7 +447,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,
 
 	err = -ENOMEM;
 
-	new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC);
+	new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC | __GFP_NOWARN);
 	if (new_tbl == NULL)
 		goto fail;