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authorPi-Hsun Shih <pihsun@chromium.org>2019-03-13 21:44:33 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-04-20 10:16:05 +0300
commit40c6d718d78c4efca4bd559adfd4b2b9a64dd6d9 (patch)
tree98a8789e1eed53d216afb994bb8ae09579c6debc
parent48b0309f85ae819da5bbe992b8769729f39c66c7 (diff)
downloadlinux-40c6d718d78c4efca4bd559adfd4b2b9a64dd6d9.tar.xz
include/linux/swap.h: use offsetof() instead of custom __swapoffset macro
[ Upstream commit a4046c06be50a4f01d435aa7fe57514818e6cc82 ] Use offsetof() to calculate offset of a field to take advantage of compiler built-in version when possible, and avoid UBSAN warning when compiling with Clang: UBSAN: Undefined behaviour in mm/swapfile.c:3010:38 member access within null pointer of type 'union swap_header' CPU: 6 PID: 1833 Comm: swapon Tainted: G S 4.19.23 #43 Call trace: dump_backtrace+0x0/0x194 show_stack+0x20/0x2c __dump_stack+0x20/0x28 dump_stack+0x70/0x94 ubsan_epilogue+0x14/0x44 ubsan_type_mismatch_common+0xf4/0xfc __ubsan_handle_type_mismatch_v1+0x34/0x54 __se_sys_swapon+0x654/0x1084 __arm64_sys_swapon+0x1c/0x24 el0_svc_common+0xa8/0x150 el0_svc_compat_handler+0x2c/0x38 el0_svc_compat+0x8/0x18 Link: http://lkml.kernel.org/r/20190312081902.223764-1-pihsun@chromium.org Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--include/linux/swap.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 77221c16733a..7bd0a6f2ac2b 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -155,9 +155,9 @@ struct swap_extent {
/*
* Max bad pages in the new format..
*/
-#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x)
#define MAX_SWAP_BADPAGES \
- ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int))
+ ((offsetof(union swap_header, magic.magic) - \
+ offsetof(union swap_header, info.badpages)) / sizeof(int))
enum {
SWP_USED = (1 << 0), /* is slot in swap_info[] used? */