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

Message

FUJITA Tomonori Feb. 20, 2025, 7:06 a.m. UTC

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/[e-mail]/
- 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/[e-mail]/
- 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/[e-mail]/
- fix compile warnings
v7: https://lore.kernel.org/lkml/[e-mail]/
- rebased on rust-next
- use crate::ffi instead of core::ffi
v6: https://lore.kernel.org/lkml/[e-mail]/
- 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/[e-mail]/
- set the range of Delta for fsleep function
- update comments
v4: https://lore.kernel.org/lkml/[e-mail]/
- 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/[e-mail]/
- 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/[e-mail]/
- 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/[e-mail]/

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