linux-kernel - Re: [PATCH net-next v2 4/6] rust: time: add wrapper for fsleep function

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Message-Id: <20241009.222859.1405378592312581525.fujita.tomonori@gmail.com>
Date: Wed, 09 Oct 2024 22:28:59 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: aliceryhl@...gle.com
Cc: fujita.tomonori@...il.com, netdev@...r.kernel.org,
 rust-for-linux@...r.kernel.org, andrew@...n.ch, hkallweit1@...il.com,
 tmgross@...ch.edu, ojeda@...nel.org, alex.gaynor@...il.com,
 gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me,
 a.hindborg@...sung.com, anna-maria@...utronix.de, frederic@...nel.org,
 tglx@...utronix.de, arnd@...db.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 4/6] rust: time: add wrapper for fsleep
 function

On Mon, 7 Oct 2024 14:24:03 +0200
Alice Ryhl <aliceryhl@...gle.com> wrote:

>> +/// Sleeps for a given duration.
>> +///
>> +/// Equivalent to the kernel's [`fsleep`], flexible sleep function,
>> +/// which automatically chooses the best sleep method based on a duration.
>> +///
>> +/// `Delta` must be longer than one microsecond.
>> +///
>> +/// This function can only be used in a nonatomic context.
>> +pub fn fsleep(delta: Delta) {
>> +    // SAFETY: FFI call.
>> +    unsafe { bindings::fsleep(delta.as_micros() as c_ulong) }
>> +}
> 
> This rounds down. Should this round it up to the nearest microsecond
> instead? It's generally said that fsleep should sleep for at least the
> provided duration, but that it may sleep for longer under some
> circumstances. By rounding up, you preserve that guarantee.

I'll round up in the next version.

> Also, the note about always sleeping for "at least" the duration may
> be a good fit for the docs here as well.

I see, will add it.