On Thu, Jul 3, 2025 at 6:41 PM Tamir Duberstein <tamird@xxxxxxxxx> wrote: > > On Thu, Jul 3, 2025 at 4:36 PM Benno Lossin <lossin@xxxxxxxxxx> wrote: > > > > 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@xxxxxxxxxx> 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@xxxxxxxxxx> 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@xxxxxxxxxx> > > >> >> > Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Custom.20formatting/with/516476467 > > >> >> > Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > >> >> > Reviewed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> > > >> >> > Signed-off-by: Tamir Duberstein <tamird@xxxxxxxxx> > > >> >> > --- > > >> >> > 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!`. > > Yes, such a split could be done - I will do so in the next spin > > > > 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. > > Yes, it probably can. As you say, some subsystems might interact - the > claimed benefit of doing this subsystem-by-subsystem split is that it > avoids conflicts with ongoing work that will conflict with a large > patch, but this is also the downside; if ongoing work changes the set > of interactions between subsystems then a maintainer may find > themselves unable to emit the log message they want (because one > subsystem is using kernel::fmt while another is still on core::fmt). I gave this a try. I ran into the problem that `format_args!` (and, after this patch, `fmt!`) is at the center of `print_macro!`, which itself underpins various other formatting macros. This means we'd have to bifurcate the formatting infrastructure to support an incremental migration. That's quite a bit of code, and likely quite a mess in the resulting git history -- and that's setting aside the toil required to figure out the correct combinations of subsystems that must migrate together.
