Re: [Jfs-discussion] [PATCH] jfs: avoid -Wtautological-constant-out-of-range-compare warning again
From: Dave Kleikamp
Date: Mon Mar 16 2026 - 11:21:10 EST
On 3/16/26 9:42AM, Arnd Bergmann via Jfs-discussion wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>
The comparison of an __s8 value against DTPAGEMAXSLOT is still trivially
true, causing a harmless (default disabled) warning with clang:
fs/jfs/jfs_dtree.c:4419:25: error: result of comparison of constant 128 with expression of type 's8' (aka 'signed char') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
4419 | p->header.freelist >= DTPAGEMAXSLOT)) {
| ~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~
I previously worked around two of these in commit 7833570dae83 ("jfs: avoid
-Wtautological-constant-out-of-range-compare warning"), but now a new one has
come up, so address the same way by dropping the redundant range check.
Thanks. I'm going to remove the comment above it as well, since it really isn't helpful.
Fixes: 119e448bb50a ("jfs: add dtpage integrity check to prevent index/pointer overflows")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
fs/jfs/jfs_dtree.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index 7669e268fe35..a32c78d1c416 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -4415,8 +4415,7 @@ bool check_dtpage(dtpage_t *p)
/* When there are free slots, freelist must be a valid slot index in
* 1~DTROOTMAXSLOT-1(since slot[0] is occupied by the header).
*/
- if (unlikely(p->header.freelist < 1 ||
- p->header.freelist >= DTPAGEMAXSLOT)) {
+ if (unlikely(p->header.freelist < 1)) {
jfs_err("Bad freelist:%d in dtpage\n", p->header.freelist);
return false;
}