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From: Sven Van Asbroeck <thesven73@gmail.com>
To: Carlos <carloscarral13@gmail.com>
Cc: rust-for-linux@vger.kernel.org
Subject: Re: Exposing semaphores
Date: Tue, 27 Apr 2021 06:18:52 -0400	[thread overview]
Message-ID: <CAGngYiUMFuzRmjM5__RUTZsp9N63zr+Y6R7kVuMU5BxRS17wcw@mail.gmail.com> (raw)
In-Reply-To: <YIdUf1C5VtWn/D2G@localhost.localdomain>

Hi Carlos,

On Mon, Apr 26, 2021 at 8:02 PM Carlos <carloscarral13@gmail.com> wrote:
>
> I recently began assessing what functionality from the kernel is missing
> for implementing a basic scull driver.
>
> Semaphores are the first missing primitive that caught my attention, and
> being such an important part of the kernel itself, I will make exposing
> this functionality my first priority instead.

Isn't scull's semaphore used exclusively in mutex mode, i.e.
initialized using init_MUTEX?

If so, prefer "struct mutex" instead. At the time scull was written
(over 15 years ago) it did not yet exist.
A Rust-for-Linux abstraction is already available:
https://github.com/Rust-for-Linux/linux/blob/rust/rust/kernel/sync/mutex.rs

This is before my time, but I believe that the use of "bare" struct
semaphores in drivers used to be a common anti-pattern, often
resulting in buggy code and/or performance issues - most semaphores
have been replaced by conceptually safer, higher-level primitives, and
today one needs a valid excuse to use them in new or even refactored
driver code. But I do not know the full story.

Sven

  parent reply	other threads:[~2021-04-27 10:23 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-27  0:02 Exposing semaphores Carlos
2021-04-27  0:08 ` Alex Gaynor
2021-04-27  0:12 ` Wedson Almeida Filho
2021-04-27  1:43   ` Samantha Miller
2021-04-27 11:00   ` Sven Van Asbroeck
2021-04-27 10:18 ` Sven Van Asbroeck [this message]
2021-04-27 10:58   ` Greg KH

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