| Message ID | 20250301231602.917580-1-ojeda@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] drm/panic: use `div_ceil` to clean Clippy warning | expand |
On Sun, Mar 2, 2025 at 12:17 AM Miguel Ojeda <ojeda@kernel.org> wrote: > > Starting with the upcoming Rust 1.86.0 (to be released 2025-04-03), > Clippy warns: > > error: manually reimplementing `div_ceil` > --> drivers/gpu/drm/drm_panic_qr.rs:548:26 > | > 548 | let pad_offset = (offset + 7) / 8; > | ^^^^^^^^^^^^^^^^ help: consider using `.div_ceil()`: `offset.div_ceil(8)` > | > = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_div_ceil > > And similarly for `stride`. Thus apply the suggestion to both. > > The behavior (and thus codegen) is not exactly equivalent [1][2], since > `div_ceil()` returns the right value for the values that currently > would overflow. > > Link: https://github.com/rust-lang/rust-clippy/issues/14333 [1] > Link: https://godbolt.org/z/dPq6nGnv3 [2] > Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Cc: stable@vger.kernel.org # Needed in 6.12.y and 6.13.y only (Rust is pinned in older LTSs). Cheers, Miguel
On Sun, Mar 2, 2025 at 12:17 AM Miguel Ojeda <ojeda@kernel.org> wrote: > > Starting with the upcoming Rust 1.86.0 (to be released 2025-04-03), > Clippy warns: > > error: manually reimplementing `div_ceil` > --> drivers/gpu/drm/drm_panic_qr.rs:548:26 > | > 548 | let pad_offset = (offset + 7) / 8; > | ^^^^^^^^^^^^^^^^ help: consider using `.div_ceil()`: `offset.div_ceil(8)` > | > = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_div_ceil > > And similarly for `stride`. Thus apply the suggestion to both. > > The behavior (and thus codegen) is not exactly equivalent [1][2], since > `div_ceil()` returns the right value for the values that currently > would overflow. > > Link: https://github.com/rust-lang/rust-clippy/issues/14333 [1] > Link: https://godbolt.org/z/dPq6nGnv3 [2] > Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
On 02/03/2025 00:16, Miguel Ojeda wrote: > Starting with the upcoming Rust 1.86.0 (to be released 2025-04-03), > Clippy warns: > > error: manually reimplementing `div_ceil` > --> drivers/gpu/drm/drm_panic_qr.rs:548:26 > | > 548 | let pad_offset = (offset + 7) / 8; > | ^^^^^^^^^^^^^^^^ help: consider using `.div_ceil()`: `offset.div_ceil(8)` > | > = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_div_ceil > > And similarly for `stride`. Thus apply the suggestion to both. > > The behavior (and thus codegen) is not exactly equivalent [1][2], since > `div_ceil()` returns the right value for the values that currently > would overflow. Thanks, so that's the DIV_ROUND_UP equivalent I was looking for. Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com> > > Link: https://github.com/rust-lang/rust-clippy/issues/14333 [1] > Link: https://godbolt.org/z/dPq6nGnv3 [2] > Signed-off-by: Miguel Ojeda <ojeda@kernel.org> > --- > drivers/gpu/drm/drm_panic_qr.rs | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs > index bcf248f69252..8bb5e52d75cc 100644 > --- a/drivers/gpu/drm/drm_panic_qr.rs > +++ b/drivers/gpu/drm/drm_panic_qr.rs > @@ -545,7 +545,7 @@ fn add_segments(&mut self, segments: &[&Segment<'_>]) { > } > self.push(&mut offset, (MODE_STOP, 4)); > > - let pad_offset = (offset + 7) / 8; > + let pad_offset = offset.div_ceil(8); > for i in pad_offset..self.version.max_data() { > self.data[i] = PADDING[(i & 1) ^ (pad_offset & 1)]; > } > @@ -659,7 +659,7 @@ struct QrImage<'a> { > impl QrImage<'_> { > fn new<'a, 'b>(em: &'b EncodedMsg<'b>, qrdata: &'a mut [u8]) -> QrImage<'a> { > let width = em.version.width(); > - let stride = (width + 7) / 8; > + let stride = width.div_ceil(8); > let data = qrdata; > > let mut qr_image = QrImage { > > base-commit: d082ecbc71e9e0bf49883ee4afd435a77a5101b6
diff --git a/drivers/gpu/drm/drm_panic_qr.rs b/drivers/gpu/drm/drm_panic_qr.rs index bcf248f69252..8bb5e52d75cc 100644 --- a/drivers/gpu/drm/drm_panic_qr.rs +++ b/drivers/gpu/drm/drm_panic_qr.rs @@ -545,7 +545,7 @@ fn add_segments(&mut self, segments: &[&Segment<'_>]) { } self.push(&mut offset, (MODE_STOP, 4)); - let pad_offset = (offset + 7) / 8; + let pad_offset = offset.div_ceil(8); for i in pad_offset..self.version.max_data() { self.data[i] = PADDING[(i & 1) ^ (pad_offset & 1)]; } @@ -659,7 +659,7 @@ struct QrImage<'a> { impl QrImage<'_> { fn new<'a, 'b>(em: &'b EncodedMsg<'b>, qrdata: &'a mut [u8]) -> QrImage<'a> { let width = em.version.width(); - let stride = (width + 7) / 8; + let stride = width.div_ceil(8); let data = qrdata; let mut qr_image = QrImage {
Starting with the upcoming Rust 1.86.0 (to be released 2025-04-03), Clippy warns: error: manually reimplementing `div_ceil` --> drivers/gpu/drm/drm_panic_qr.rs:548:26 | 548 | let pad_offset = (offset + 7) / 8; | ^^^^^^^^^^^^^^^^ help: consider using `.div_ceil()`: `offset.div_ceil(8)` | = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_div_ceil And similarly for `stride`. Thus apply the suggestion to both. The behavior (and thus codegen) is not exactly equivalent [1][2], since `div_ceil()` returns the right value for the values that currently would overflow. Link: https://github.com/rust-lang/rust-clippy/issues/14333 [1] Link: https://godbolt.org/z/dPq6nGnv3 [2] Signed-off-by: Miguel Ojeda <ojeda@kernel.org> --- drivers/gpu/drm/drm_panic_qr.rs | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) base-commit: d082ecbc71e9e0bf49883ee4afd435a77a5101b6