Benno Lossin
2025-Jul-03 15:08 UTC
[PATCH v13 2/5] rust: support formatting of foreign types
On Thu Jul 3, 2025 at 3:55 PM CEST, Tamir Duberstein wrote:> On Thu, Jul 3, 2025 at 5:32?AM Benno Lossin <lossin at kernel.org> wrote: >> On Tue Jul 1, 2025 at 6:49 PM CEST, Tamir Duberstein wrote: >> > Introduce a `fmt!` macro which wraps all arguments in >> > `kernel::fmt::Adapter` and a `kernel::fmt::Display` trait. This enables >> > formatting of foreign types (like `core::ffi::CStr`) that do not >> > implement `core::fmt::Display` due to concerns around lossy conversions which >> > do not apply in the kernel. >> > >> > Replace all direct calls to `format_args!` with `fmt!`. >> > >> > Replace all implementations of `core::fmt::Display` with implementations >> > of `kernel::fmt::Display`. >> > >> > Suggested-by: Alice Ryhl <aliceryhl at google.com> >> > Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 >> > Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org> >> > Reviewed-by: Alice Ryhl <aliceryhl at google.com> >> > Signed-off-by: Tamir Duberstein <tamird at gmail.com> >> > --- >> > drivers/block/rnull.rs | 2 +- >> > drivers/gpu/nova-core/gpu.rs | 4 +- >> > rust/kernel/block/mq.rs | 2 +- >> > rust/kernel/device.rs | 2 +- >> > rust/kernel/fmt.rs | 89 +++++++++++++++++++++++++++++++++++++++ >> > rust/kernel/kunit.rs | 6 +-- >> > rust/kernel/lib.rs | 1 + >> > rust/kernel/prelude.rs | 3 +- >> > rust/kernel/print.rs | 4 +- >> > rust/kernel/seq_file.rs | 2 +- >> > rust/kernel/str.rs | 22 ++++------ >> > rust/macros/fmt.rs | 99 ++++++++++++++++++++++++++++++++++++++++++++ >> > rust/macros/lib.rs | 19 +++++++++ >> > rust/macros/quote.rs | 7 ++++ >> > scripts/rustdoc_test_gen.rs | 2 +- >> > 15 files changed, 236 insertions(+), 28 deletions(-) >> >> This would be a lot easier to review if he proc-macro and the call >> replacement were different patches. >> >> Also the `kernel/fmt.rs` file should be a different commit. > > Can you help me understand why? The changes you ask to be separated > would all be in different files, so why would separate commits make it > easier to review?It takes less time to go through the entire patch and give a RB. I can take smaller time chunks and don't have to get back into the entire context of the patch when I don't have 30-60min available. In this patch the biggest problem is the rename & addition of new things, maybe just adding 200 lines in those files could be okay to go together, see below for more.> I prefer to keep things in one commit because the changes are highly > interdependent. The proc macro doesn't make sense without > kernel/fmt.rs and kernel/fmt.rs is useless without the proc macro.I think that `Adapter`, the custom `Display` and their impl blocks don't need to be in the same commit as the proc-macro. They are related, but maybe someone is not well-versed in proc-macros and thus doesn't want to review that part.>> > diff --git a/rust/kernel/fmt.rs b/rust/kernel/fmt.rs >> > new file mode 100644 >> > index 000000000000..348d16987de6 >> > --- /dev/null >> > +++ b/rust/kernel/fmt.rs >> > @@ -0,0 +1,89 @@ >> > +// SPDX-License-Identifier: GPL-2.0 >> > + >> > +//! Formatting utilities. >> > + >> > +use core::fmt; >> >> I think we should pub export all types that we are still using from >> `core::fmt`. For example `Result`, `Formatter`, `Debug` etc. >> >> That way I can still use the same pattern of importing `fmt` and then >> writing >> >> impl fmt::Display for MyType { >> fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {} >> } > > Great idea, done for the next spin. It would be nice to be able to > lint against references to `core::fmt` outside of kernel/fmt.rs.I think there was something in clippy that can do that globally and we could allow that in this file?>> > + >> > +/// Internal adapter used to route allow implementations of formatting traits for foreign types. >> > +/// >> > +/// It is inserted automatically by the [`fmt!`] macro and is not meant to be used directly. >> > +/// >> > +/// [`fmt!`]: crate::prelude::fmt! >> > +#[doc(hidden)] >> > +pub struct Adapter<T>(pub T); >> > + >> > +macro_rules! impl_fmt_adapter_forward { >> > + ($($trait:ident),* $(,)?) => { >> > + $( >> > + impl<T: fmt::$trait> fmt::$trait for Adapter<T> { >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { >> > + let Self(t) = self; >> > + fmt::$trait::fmt(t, f) >> > + } >> > + } >> > + )* >> > + }; >> > +} >> > + >> > +impl_fmt_adapter_forward!(Debug, LowerHex, UpperHex, Octal, Binary, Pointer, LowerExp, UpperExp); >> > + >> > +/// A copy of [`fmt::Display`] that allows us to implement it for foreign types. >> > +/// >> > +/// Types should implement this trait rather than [`fmt::Display`]. Together with the [`Adapter`] >> > +/// type and [`fmt!`] macro, it allows for formatting foreign types (e.g. types from core) which do >> > +/// not implement [`fmt::Display`] directly. >> > +/// >> > +/// [`fmt!`]: crate::prelude::fmt! >> > +pub trait Display { >> > + /// Same as [`fmt::Display::fmt`]. >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result; >> > +} >> > + >> > +impl<T: ?Sized + Display> Display for &T { >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { >> > + Display::fmt(*self, f) >> > + } >> > +} >> > + >> > +impl<T: ?Sized + Display> fmt::Display for Adapter<&T> { >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { >> > + let Self(t) = self; >> > + Display::fmt(t, f) >> >> Why not `Display::fmt(&self.0, f)`? > > I like destructuring because it shows me that there's only one field. > With `self.0` I don't see that.And what is the benefit here?>> > + >> > + let mut args = TokenStream::from_iter(first_opt); >> > + { >> > + let mut flush = |args: &mut TokenStream, current: &mut TokenStream| { >> >> You don't need to pass `args` as a closure argument, since you always >> call it with `&mut args`. > > This doesn't work because of the borrow checker. If I wrote what you > suggest, then `args` is mutably borrowed by the closure, which > prohibits the mutable borrow needed for the .extend() call here:Ahh right... Well then it's fine. --- Cheers, Benno
Tamir Duberstein
2025-Jul-03 18:56 UTC
[PATCH v13 2/5] rust: support formatting of foreign types
On Thu, Jul 3, 2025 at 11:08?AM Benno Lossin <lossin at kernel.org> wrote:> > On Thu Jul 3, 2025 at 3:55 PM CEST, Tamir Duberstein wrote: > > On Thu, Jul 3, 2025 at 5:32?AM Benno Lossin <lossin at kernel.org> wrote: > >> On Tue Jul 1, 2025 at 6:49 PM CEST, Tamir Duberstein wrote: > >> > Introduce a `fmt!` macro which wraps all arguments in > >> > `kernel::fmt::Adapter` and a `kernel::fmt::Display` trait. This enables > >> > formatting of foreign types (like `core::ffi::CStr`) that do not > >> > implement `core::fmt::Display` due to concerns around lossy conversions which > >> > do not apply in the kernel. > >> > > >> > Replace all direct calls to `format_args!` with `fmt!`. > >> > > >> > Replace all implementations of `core::fmt::Display` with implementations > >> > of `kernel::fmt::Display`. > >> > > >> > Suggested-by: Alice Ryhl <aliceryhl at google.com> > >> > Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 > >> > Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org> > >> > Reviewed-by: Alice Ryhl <aliceryhl at google.com> > >> > Signed-off-by: Tamir Duberstein <tamird at gmail.com> > >> > --- > >> > drivers/block/rnull.rs | 2 +- > >> > drivers/gpu/nova-core/gpu.rs | 4 +- > >> > rust/kernel/block/mq.rs | 2 +- > >> > rust/kernel/device.rs | 2 +- > >> > rust/kernel/fmt.rs | 89 +++++++++++++++++++++++++++++++++++++++ > >> > rust/kernel/kunit.rs | 6 +-- > >> > rust/kernel/lib.rs | 1 + > >> > rust/kernel/prelude.rs | 3 +- > >> > rust/kernel/print.rs | 4 +- > >> > rust/kernel/seq_file.rs | 2 +- > >> > rust/kernel/str.rs | 22 ++++------ > >> > rust/macros/fmt.rs | 99 ++++++++++++++++++++++++++++++++++++++++++++ > >> > rust/macros/lib.rs | 19 +++++++++ > >> > rust/macros/quote.rs | 7 ++++ > >> > scripts/rustdoc_test_gen.rs | 2 +- > >> > 15 files changed, 236 insertions(+), 28 deletions(-) > >> > >> This would be a lot easier to review if he proc-macro and the call > >> replacement were different patches. > >> > >> Also the `kernel/fmt.rs` file should be a different commit. > > > > Can you help me understand why? The changes you ask to be separated > > would all be in different files, so why would separate commits make it > > easier to review? > > It takes less time to go through the entire patch and give a RB. I can > take smaller time chunks and don't have to get back into the entire > context of the patch when I don't have 30-60min available.Ah, I see what you mean. Yeah, the requirement to RB the entire patch does mean there's a benefit to smaller patches.> In this patch the biggest problem is the rename & addition of new > things, maybe just adding 200 lines in those files could be okay to go > together, see below for more.After implementing your suggestion of re-exporting things from `kernel::fmt` the diffstat is 26 files changed, 253 insertions(+), 51 deletions(-) so I guess I could do all the additions in one patch, but then *everything* else has to go in a single patch together because the formatting macros either want core::fmt::Display or kernel::fmt::Display; they can't work in a halfway state.> > > I prefer to keep things in one commit because the changes are highly > > interdependent. The proc macro doesn't make sense without > > kernel/fmt.rs and kernel/fmt.rs is useless without the proc macro. > > I think that `Adapter`, the custom `Display` and their impl blocks > don't need to be in the same commit as the proc-macro. They are related, > but maybe someone is not well-versed in proc-macros and thus doesn't > want to review that part.Sure, I guess I will split them. But as noted above: changing the formatting macros and all the types' trait implementations has to be a "flag day" change.> > >> > diff --git a/rust/kernel/fmt.rs b/rust/kernel/fmt.rs > >> > new file mode 100644 > >> > index 000000000000..348d16987de6 > >> > --- /dev/null > >> > +++ b/rust/kernel/fmt.rs > >> > @@ -0,0 +1,89 @@ > >> > +// SPDX-License-Identifier: GPL-2.0 > >> > + > >> > +//! Formatting utilities. > >> > + > >> > +use core::fmt; > >> > >> I think we should pub export all types that we are still using from > >> `core::fmt`. For example `Result`, `Formatter`, `Debug` etc. > >> > >> That way I can still use the same pattern of importing `fmt` and then > >> writing > >> > >> impl fmt::Display for MyType { > >> fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {} > >> } > > > > Great idea, done for the next spin. It would be nice to be able to > > lint against references to `core::fmt` outside of kernel/fmt.rs. > > I think there was something in clippy that can do that globally and we > could allow that in this file?I didn't find anything suitable. Do you have one in mind?> >> > + > >> > +/// Internal adapter used to route allow implementations of formatting traits for foreign types. > >> > +/// > >> > +/// It is inserted automatically by the [`fmt!`] macro and is not meant to be used directly. > >> > +/// > >> > +/// [`fmt!`]: crate::prelude::fmt! > >> > +#[doc(hidden)] > >> > +pub struct Adapter<T>(pub T); > >> > + > >> > +macro_rules! impl_fmt_adapter_forward { > >> > + ($($trait:ident),* $(,)?) => { > >> > + $( > >> > + impl<T: fmt::$trait> fmt::$trait for Adapter<T> { > >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { > >> > + let Self(t) = self; > >> > + fmt::$trait::fmt(t, f) > >> > + } > >> > + } > >> > + )* > >> > + }; > >> > +} > >> > + > >> > +impl_fmt_adapter_forward!(Debug, LowerHex, UpperHex, Octal, Binary, Pointer, LowerExp, UpperExp); > >> > + > >> > +/// A copy of [`fmt::Display`] that allows us to implement it for foreign types. > >> > +/// > >> > +/// Types should implement this trait rather than [`fmt::Display`]. Together with the [`Adapter`] > >> > +/// type and [`fmt!`] macro, it allows for formatting foreign types (e.g. types from core) which do > >> > +/// not implement [`fmt::Display`] directly. > >> > +/// > >> > +/// [`fmt!`]: crate::prelude::fmt! > >> > +pub trait Display { > >> > + /// Same as [`fmt::Display::fmt`]. > >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result; > >> > +} > >> > + > >> > +impl<T: ?Sized + Display> Display for &T { > >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { > >> > + Display::fmt(*self, f) > >> > + } > >> > +} > >> > + > >> > +impl<T: ?Sized + Display> fmt::Display for Adapter<&T> { > >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { > >> > + let Self(t) = self; > >> > + Display::fmt(t, f) > >> > >> Why not `Display::fmt(&self.0, f)`? > > > > I like destructuring because it shows me that there's only one field. > > With `self.0` I don't see that. > > And what is the benefit here?In general the benefit is that the method does not ignore some portion of `Self`. A method that uses `self.0` would not provoke a compiler error in case another field is added, while this form would.> > >> > + > >> > + let mut args = TokenStream::from_iter(first_opt); > >> > + { > >> > + let mut flush = |args: &mut TokenStream, current: &mut TokenStream| { > >> > >> You don't need to pass `args` as a closure argument, since you always > >> call it with `&mut args`. > > > > This doesn't work because of the borrow checker. If I wrote what you > > suggest, then `args` is mutably borrowed by the closure, which > > prohibits the mutable borrow needed for the .extend() call here: > > Ahh right... Well then it's fine. > > --- > Cheers, > Benno
Benno Lossin
2025-Jul-03 20:36 UTC
[PATCH v13 2/5] rust: support formatting of foreign types
On Thu Jul 3, 2025 at 8:55 PM CEST, Tamir Duberstein wrote:> On Thu, Jul 3, 2025 at 11:08?AM Benno Lossin <lossin at kernel.org> wrote: >> On Thu Jul 3, 2025 at 3:55 PM CEST, Tamir Duberstein wrote: >> > On Thu, Jul 3, 2025 at 5:32?AM Benno Lossin <lossin at kernel.org> wrote: >> >> On Tue Jul 1, 2025 at 6:49 PM CEST, Tamir Duberstein wrote: >> >> > Introduce a `fmt!` macro which wraps all arguments in >> >> > `kernel::fmt::Adapter` and a `kernel::fmt::Display` trait. This enables >> >> > formatting of foreign types (like `core::ffi::CStr`) that do not >> >> > implement `core::fmt::Display` due to concerns around lossy conversions which >> >> > do not apply in the kernel. >> >> > >> >> > Replace all direct calls to `format_args!` with `fmt!`. >> >> > >> >> > Replace all implementations of `core::fmt::Display` with implementations >> >> > of `kernel::fmt::Display`. >> >> > >> >> > Suggested-by: Alice Ryhl <aliceryhl at google.com> >> >> > Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 >> >> > Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org> >> >> > Reviewed-by: Alice Ryhl <aliceryhl at google.com> >> >> > Signed-off-by: Tamir Duberstein <tamird at gmail.com> >> >> > --- >> >> > drivers/block/rnull.rs | 2 +- >> >> > drivers/gpu/nova-core/gpu.rs | 4 +- >> >> > rust/kernel/block/mq.rs | 2 +- >> >> > rust/kernel/device.rs | 2 +- >> >> > rust/kernel/fmt.rs | 89 +++++++++++++++++++++++++++++++++++++++ >> >> > rust/kernel/kunit.rs | 6 +-- >> >> > rust/kernel/lib.rs | 1 + >> >> > rust/kernel/prelude.rs | 3 +- >> >> > rust/kernel/print.rs | 4 +- >> >> > rust/kernel/seq_file.rs | 2 +- >> >> > rust/kernel/str.rs | 22 ++++------ >> >> > rust/macros/fmt.rs | 99 ++++++++++++++++++++++++++++++++++++++++++++ >> >> > rust/macros/lib.rs | 19 +++++++++ >> >> > rust/macros/quote.rs | 7 ++++ >> >> > scripts/rustdoc_test_gen.rs | 2 +- >> >> > 15 files changed, 236 insertions(+), 28 deletions(-) >> >> >> >> This would be a lot easier to review if he proc-macro and the call >> >> replacement were different patches. >> >> >> >> Also the `kernel/fmt.rs` file should be a different commit. >> > >> > Can you help me understand why? The changes you ask to be separated >> > would all be in different files, so why would separate commits make it >> > easier to review? >> >> It takes less time to go through the entire patch and give a RB. I can >> take smaller time chunks and don't have to get back into the entire >> context of the patch when I don't have 30-60min available. > > Ah, I see what you mean. Yeah, the requirement to RB the entire patch > does mean there's a benefit to smaller patches. > >> In this patch the biggest problem is the rename & addition of new >> things, maybe just adding 200 lines in those files could be okay to go >> together, see below for more. > > After implementing your suggestion of re-exporting things from > `kernel::fmt` the diffstat is > > 26 files changed, 253 insertions(+), 51 deletions(-) > > so I guess I could do all the additions in one patch, but then > *everything* else has to go in a single patch together because the > formatting macros either want core::fmt::Display or > kernel::fmt::Display; they can't work in a halfway state.I don't understand, can't you just do: * add `rust/kernel/fmt.rs`, * add `rust/macros/fmt.rs`, * change all occurrences of `core::fmt` to `kernel::fmt` and `format_args!` to `fmt!`. The last one could be split by subsystem, no? Some subsystems might interact and thus need simultaneous splitting, but there should be some independent ones.>> > I prefer to keep things in one commit because the changes are highly >> > interdependent. The proc macro doesn't make sense without >> > kernel/fmt.rs and kernel/fmt.rs is useless without the proc macro. >> >> I think that `Adapter`, the custom `Display` and their impl blocks >> don't need to be in the same commit as the proc-macro. They are related, >> but maybe someone is not well-versed in proc-macros and thus doesn't >> want to review that part. > > Sure, I guess I will split them. But as noted above: changing the > formatting macros and all the types' trait implementations has to be a > "flag day" change.See above.>> >> > +impl_fmt_adapter_forward!(Debug, LowerHex, UpperHex, Octal, Binary, Pointer, LowerExp, UpperExp); >> >> > + >> >> > +/// A copy of [`fmt::Display`] that allows us to implement it for foreign types. >> >> > +/// >> >> > +/// Types should implement this trait rather than [`fmt::Display`]. Together with the [`Adapter`] >> >> > +/// type and [`fmt!`] macro, it allows for formatting foreign types (e.g. types from core) which do >> >> > +/// not implement [`fmt::Display`] directly. >> >> > +/// >> >> > +/// [`fmt!`]: crate::prelude::fmt! >> >> > +pub trait Display { >> >> > + /// Same as [`fmt::Display::fmt`]. >> >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result; >> >> > +} >> >> > + >> >> > +impl<T: ?Sized + Display> Display for &T { >> >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { >> >> > + Display::fmt(*self, f) >> >> > + } >> >> > +} >> >> > + >> >> > +impl<T: ?Sized + Display> fmt::Display for Adapter<&T> { >> >> > + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { >> >> > + let Self(t) = self; >> >> > + Display::fmt(t, f) >> >> >> >> Why not `Display::fmt(&self.0, f)`? >> > >> > I like destructuring because it shows me that there's only one field. >> > With `self.0` I don't see that. >> >> And what is the benefit here? > > In general the benefit is that the method does not ignore some portion > of `Self`. A method that uses `self.0` would not provoke a compiler > error in case another field is added, while this form would.Yeah, but why would that change happen here? And even if it got another field, why would that invalidate the impl of `fn fmt`? --- Cheers, Benno
Andrew Lunn
2025-Jul-03 21:28 UTC
[PATCH v13 2/5] rust: support formatting of foreign types
On Thu, Jul 03, 2025 at 02:55:30PM -0400, Tamir Duberstein wrote:> On Thu, Jul 3, 2025 at 11:08?AM Benno Lossin <lossin at kernel.org> wrote: > > > > On Thu Jul 3, 2025 at 3:55 PM CEST, Tamir Duberstein wrote: > > > On Thu, Jul 3, 2025 at 5:32?AM Benno Lossin <lossin at kernel.org> wrote: > > >> On Tue Jul 1, 2025 at 6:49 PM CEST, Tamir Duberstein wrote: > > >> > Introduce a `fmt!` macro which wraps all arguments in > > >> > `kernel::fmt::Adapter` and a `kernel::fmt::Display` trait. This enables > > >> > formatting of foreign types (like `core::ffi::CStr`) that do not > > >> > implement `core::fmt::Display` due to concerns around lossy conversions which > > >> > do not apply in the kernel. > > >> > > > >> > Replace all direct calls to `format_args!` with `fmt!`. > > >> > > > >> > Replace all implementations of `core::fmt::Display` with implementations > > >> > of `kernel::fmt::Display`. > > >> > > > >> > Suggested-by: Alice Ryhl <aliceryhl at google.com> > > >> > Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 > > >> > Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org> > > >> > Reviewed-by: Alice Ryhl <aliceryhl at google.com> > > >> > Signed-off-by: Tamir Duberstein <tamird at gmail.com> > > >> > --- > > >> > drivers/block/rnull.rs | 2 +- > > >> > drivers/gpu/nova-core/gpu.rs | 4 +- > > >> > rust/kernel/block/mq.rs | 2 +- > > >> > rust/kernel/device.rs | 2 +- > > >> > rust/kernel/fmt.rs | 89 +++++++++++++++++++++++++++++++++++++++ > > >> > rust/kernel/kunit.rs | 6 +-- > > >> > rust/kernel/lib.rs | 1 + > > >> > rust/kernel/prelude.rs | 3 +- > > >> > rust/kernel/print.rs | 4 +- > > >> > rust/kernel/seq_file.rs | 2 +- > > >> > rust/kernel/str.rs | 22 ++++------ > > >> > rust/macros/fmt.rs | 99 ++++++++++++++++++++++++++++++++++++++++++++ > > >> > rust/macros/lib.rs | 19 +++++++++ > > >> > rust/macros/quote.rs | 7 ++++ > > >> > scripts/rustdoc_test_gen.rs | 2 +- > > >> > 15 files changed, 236 insertions(+), 28 deletions(-) > > >> > > >> This would be a lot easier to review if he proc-macro and the call > > >> replacement were different patches. > > >> > > >> Also the `kernel/fmt.rs` file should be a different commit. > > > > > > Can you help me understand why? The changes you ask to be separated > > > would all be in different files, so why would separate commits make it > > > easier to review? > > > > It takes less time to go through the entire patch and give a RB. I can > > take smaller time chunks and don't have to get back into the entire > > context of the patch when I don't have 30-60min available. > > Ah, I see what you mean. Yeah, the requirement to RB the entire patch > does mean there's a benefit to smaller patches.I often tell kernel newbies: Lots of small patches which are obviously correct. A small patch tends to be more obviously correct than a big patch. The commit message is more focused and helpful because it refers to a small chunk of code. Because the commit message is more focused, it can answer questions reviewers might ask, before they ask them. If i can spend 60 seconds looking at a patch and decide it looks correct, i'm more likely to actually look at it and give a reviewed by. If i need to find 10 minutes, it is going to get put off for a later time. Many reviewers just have a few minutes here, a few there, slotted into time between other tasks, while drinking coffee, etc. Andrew