get rid of INT_LIMIT, use type_max() instead

INT_LIMIT() tries to do what type_max() does, except that type_max()
doesn't rely upon undefined behaviour[*], might as well use type_max()
instead.

[*] if T is an N-bit signed integer type, the maximal value in T is
pow(2, N - 1) - 1, all right, but naive expression for that value
ends up with a couple of wraparounds and as usual for wraparounds
in signed types, that's an undefined behaviour.  type_max() takes
care to avoid those...

Caught-by: UBSAN
Suggested-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e654435f16512c122f176d0ab447925ae94f75fc..a384741b1449457bf32499be225ea31ba79a3a69 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1131,9 +1131,8 @@ struct file_lock_context {
 
 /* The following constant reflects the upper bound of the file/locking space */
 #ifndef OFFSET_MAX
-#define INT_LIMIT(x)   (~((x)1 << (sizeof(x)*8 - 1)))
-#define OFFSET_MAX     INT_LIMIT(loff_t)
-#define OFFT_OFFSET_MAX        INT_LIMIT(off_t)
+#define OFFSET_MAX     type_max(loff_t)
+#define OFFT_OFFSET_MAX        type_max(off_t)
 #endif
 
 extern void send_sigio(struct fown_struct *fown, int fd, int band);