[PATCH v11 0/8] rust: Add IO polling

FUJITA Tomonori
2025-02-20T07:10:12Z

Add a helper function to poll periodically until a condition is met or
a timeout is reached. By using the function, the 8th patch fixes
QT2025 PHY driver to sleep until the hardware becomes ready.

The first patch is for sched/core, which adds
__might_sleep_precision(), rust friendly version of __might_sleep(),
which takes a pointer to a string with the length instead of a
null-terminated string. Rust's core::panic::Location::file(), which
gives the file name of a caller, doesn't provide a null-terminated
string. __might_sleep_precision() uses a precision specifier in the
printk format, which specifies the length of a string; a string
doesn't need to be a null-terminated.

The remaining patches are for the Rust portion and updates to the
MAINTAINERS file.

This introduces two new types, Instant and Delta, which represent a
specific point in time and a span of time, respectively.

Unlike the old rust branch, This adds a wrapper for fsleep() instead
of msleep(). fsleep() automatically chooses the best sleep method
based on a duration.

[1]: https://github.com/rust-lang/libs-team/issues/466

v11
- use file_len arg name in __might_resched_precision() instead of len for clarity
- remove unnecessary strlen in __might_resched(); just use a large value for the precision
- add more doc and example for read_poll_timeout()
- fix read_poll_timeout() to call __might_sleep() only with CONFIG_DEBUG_ATOMIC_SLEEP enabled
- call might_sleep() instead of __might_sleep() in read_poll_timeout() to match the C version
- Add new sections for the abstractions in MAINTAINERS instead of adding rust files to the existing sections
v10: https://lore.kernel.org/netdev/20250207132623.168854-1-fujita.tomonori@gmail.com/
- rebased on rust-next
- use Option type for timeout argument for read_poll_timeout()
- remove obsoleted comment on read_poll_timeout()
v9: https://lore.kernel.org/lkml/20250125101854.112261-1-fujita.tomonori@gmail.com/
- make the might_sleep() changes into as a separate patch
- add as_millis() method to Delta for Binder driver
- make Delta's as_*() methods const (useful in some use cases)
- add Delta::ZERO const; used in fsleep()
- fix typos
- use intra-doc links
- place the #[inline] marker before the documentation
- remove Instant's from_raw() method
- add Invariants to Instant type
- improve Delta's methods documents
- fix fsleep() SAFETY comment
- improve fsleep() documents
- lift T:Copy restriction in read_poll_timeout()
- use MutFn for Cond in read_poll_timeout() instead of Fn
- fix might_sleep() call in read_poll_timeout()
- simplify read_poll_timeout() logic
v8: https://lore.kernel.org/lkml/20250116044100.80679-1-fujita.tomonori@gmail.com/
- fix compile warnings
v7: https://lore.kernel.org/lkml/20241220061853.2782878-1-fujita.tomonori@gmail.com/
- rebased on rust-next
- use crate::ffi instead of core::ffi
v6: https://lore.kernel.org/lkml/20241114070234.116329-1-fujita.tomonori@gmail.com/
- use super::Delta in delay.rs
- improve the comments
- add Delta's is_negative() method
- rename processor.rs to cpu.rs for cpu_relax()
- add __might_sleep_precision() taking pointer to a string with the length
- implement read_poll_timeout as normal function instead of macro
v5: https://lore.kernel.org/lkml/20241101010121.69221-1-fujita.tomonori@gmail.com/
- set the range of Delta for fsleep function
- update comments
v4: https://lore.kernel.org/lkml/20241025033118.44452-1-fujita.tomonori@gmail.com/
- rebase on the tip tree's timers/core
- add Instant instead of using Ktime
- remove unused basic methods
- add Delta as_micros_ceil method
- use const fn for Delta from_* methods
- add more comments based on the feedback
- add a safe wrapper for cpu_relax()
- add __might_sleep() macro
v3: https://lore.kernel.org/lkml/20241016035214.2229-1-fujita.tomonori@gmail.com/
- Update time::Delta methods (use i64 for everything)
- Fix read_poll_timeout to show the proper debug info (file and line)
- Move fsleep to rust/kernel/time/delay.rs
- Round up delta for fsleep
- Access directly ktime_t instead of using ktime APIs
- Add Eq and Ord with PartialEq and PartialOrd
v2: https://lore.kernel.org/lkml/20241005122531.20298-1-fujita.tomonori@gmail.com/
- Introduce time::Delta instead of core::time::Duration
- Add some trait to Ktime for calculating timeout
- Use read_poll_timeout in QT2025 driver instead of using fsleep directly
v1: https://lore.kernel.org/netdev/20241001112512.4861-1-fujita.tomonori@gmail.com/

FUJITA Tomonori (8):
sched/core: Add __might_sleep_precision()
rust: time: Add PartialEq/Eq/PartialOrd/Ord trait to Ktime
rust: time: Introduce Delta type
rust: time: Introduce Instant type
rust: time: Add wrapper for fsleep() function
MAINTAINERS: rust: Add new sections for DELAY/SLEEP and TIMEKEEPING
API
rust: Add read_poll_timeout functions
net: phy: qt2025: Wait until PHY becomes ready

MAINTAINERS | 14 ++++
drivers/net/phy/qt2025.rs | 10 ++-
include/linux/kernel.h | 2 +
kernel/sched/core.c | 61 +++++++++------
rust/helpers/helpers.c | 2 +
rust/helpers/kernel.c | 18 +++++
rust/helpers/time.c | 8 ++
rust/kernel/cpu.rs | 13 ++++
rust/kernel/error.rs | 1 +
rust/kernel/io.rs | 2 +
rust/kernel/io/poll.rs | 120 +++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
rust/kernel/time.rs | 155 ++++++++++++++++++++++++++++++--------
rust/kernel/time/delay.rs | 49 ++++++++++++
14 files changed, 402 insertions(+), 54 deletions(-)
create mode 100644 rust/helpers/kernel.c
create mode 100644 rust/helpers/time.c
create mode 100644 rust/kernel/cpu.rs
create mode 100644 rust/kernel/io/poll.rs
create mode 100644 rust/kernel/time/delay.rs

base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d
--
2.43.0