| Message ID | 20240328143051.1069575-4-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | address remaining -Wtautological-constant-out-of-range-compare | expand |
On 3/28/24 9:30 AM, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > clang-14 points out that the range check is always true on 64-bit > architectures since a u32 is not greater than the allowed size: > > drivers/block/rbd.c:6079:17: error: result of comparison of constant 2305843009213693948 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare] w > ~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This is harmless, so just change the type of the temporary to size_t > to shut up that warning. This fixes the warning, but then the now size_t value is passed to ceph_decode_32_safe(), which implies a different type conversion. That too is not harmful, but... Could we just cast the value in the comparison instead? if ((size_t)snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context)) You could drop the space between sizeof and ( while you're at it (I always used the space back then). -Alex > > Fixes: bb23e37acb2a ("rbd: refactor rbd_header_from_disk()") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/block/rbd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c > index 26ff5cd2bf0a..cb25ee513ada 100644 > --- a/drivers/block/rbd.c > +++ b/drivers/block/rbd.c > @@ -6062,7 +6062,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, > void *p; > void *end; > u64 seq; > - u32 snap_count; > + size_t snap_count; > struct ceph_snap_context *snapc; > u32 i; >
On 3/28/24 22:53, Alex Elder wrote: > On 3/28/24 9:30 AM, Arnd Bergmann wrote: >> From: Arnd Bergmann <arnd@arndb.de> >> >> clang-14 points out that the range check is always true on 64-bit >> architectures since a u32 is not greater than the allowed size: >> >> drivers/block/rbd.c:6079:17: error: result of comparison of constant >> 2305843009213693948 with expression of type 'u32' (aka 'unsigned >> int') is always false >> [-Werror,-Wtautological-constant-out-of-range-compare] > w >> ~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> This is harmless, so just change the type of the temporary to size_t >> to shut up that warning. > > This fixes the warning, but then the now size_t value is passed > to ceph_decode_32_safe(), which implies a different type conversion. > That too is not harmful, but... > > Could we just cast the value in the comparison instead? > > if ((size_t)snap_count > (SIZE_MAX - sizeof (struct ceph_snap_context)) > > You could drop the space between sizeof and ( while > you're at it (I always used the space back then). > Agree. - Xiubo > -Alex > >> >> Fixes: bb23e37acb2a ("rbd: refactor rbd_header_from_disk()") >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> --- >> drivers/block/rbd.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c >> index 26ff5cd2bf0a..cb25ee513ada 100644 >> --- a/drivers/block/rbd.c >> +++ b/drivers/block/rbd.c >> @@ -6062,7 +6062,7 @@ static int rbd_dev_v2_snap_context(struct >> rbd_device *rbd_dev, >> void *p; >> void *end; >> u64 seq; >> - u32 snap_count; >> + size_t snap_count; >> struct ceph_snap_context *snapc; >> u32 i; > >
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 26ff5cd2bf0a..cb25ee513ada 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -6062,7 +6062,7 @@ static int rbd_dev_v2_snap_context(struct rbd_device *rbd_dev, void *p; void *end; u64 seq; - u32 snap_count; + size_t snap_count; struct ceph_snap_context *snapc; u32 i;