linux-kernel - [PATCH 09/13] lib/generic-radix-tree: Check sizeof(

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Message-ID: <9ddf843612ea429682b68d5747bd93d8@AcuMS.aculab.com>
Date:   Tue, 25 Aug 2020 14:52:50 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "'linux-sctp@...r.kernel.org'" <linux-sctp@...r.kernel.org>,
        Eric Biggers <ebiggers@...nel.org>,
        'Marcelo Ricardo Leitner' <marcelo.leitner@...il.com>,
        'Catalin Marinas' <catalin.marinas@....com>,
        "'kent.overstreet@...il.com'" <kent.overstreet@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "'Neil Horman'" <nhorman@...driver.com>
Subject: [PATCH 09/13] lib/generic-radix-tree: Check sizeof(_type) when
 defining a tree.

Move the check for the structure type being larger than PAGE_SIZE from every
use to the definition of a tree.

Signed-off-by: David Laight <david.laight@...lab.com>
---
 include/linux/generic-radix-tree.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/include/linux/generic-radix-tree.h b/include/linux/generic-radix-tree.h
index bfd00320c7f3..53149bc1b92a 100644
--- a/include/linux/generic-radix-tree.h
+++ b/include/linux/generic-radix-tree.h
@@ -64,12 +64,14 @@ struct __genradix {
  * to it for casts/sizeof - we also force the alignment so that storing a type
  * with a ridiculous alignment doesn't blow up the alignment or size of the
  * genradix.
+ *
+ * Generates a compile-time error if the item is too large.
  */
 
 #define GENRADIX(_type)						\
 struct {							\
 	struct __genradix	tree;				\
-	_type			type[0] __aligned(1);		\
+	_type type[sizeof (_type) <= PAGE_SIZE ? 0 : -1] __aligned(1);	\
 }
 
 #define DEFINE_GENRADIX(_name, _type)				\
@@ -98,11 +100,6 @@ void __genradix_free(struct __genradix *);
 
 static inline size_t __idx_to_offset(size_t idx, size_t obj_size)
 {
-	if (__builtin_constant_p(obj_size))
-		BUILD_BUG_ON(obj_size > PAGE_SIZE);
-	else
-		BUG_ON(obj_size > PAGE_SIZE);
-
 	if (!is_power_of_2(obj_size)) {
 		size_t objs_per_page = PAGE_SIZE / obj_size;
 
-- 
2.25.1

-
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