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Date: Wed, 25 Mar 2020 17:02:12 +0100
From: Sebastian Siewior <bigeasy@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Documentation/locking/locktypes: Further clarifications and
 wordsmithing
Message-ID: <20200325160212.oavrni7gmzudnczv@linutronix.de>
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On 2020-03-25 13:27:49 [+0100], Thomas Gleixner wrote:
> The documentation of rw_semaphores is wrong as it claims that the non-own=
er
> reader release is not supported by RT. That's just history biased memory
> distortion.
>=20
> Split the 'Owner semantics' section up and add separate sections for
> semaphore and rw_semaphore to reflect reality.
>=20
> Aside of that the following updates are done:
>=20
>  - Add pseudo code to document the spinlock state preserving mechanism on
>    PREEMPT_RT
>=20
>  - Wordsmith the bitspinlock and lock nesting sections
>=20
> Co-developed-by: Paul McKenney <paulmck@kernel.org>
> Signed-off-by: Paul McKenney <paulmck@kernel.org>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

> --- a/Documentation/locking/locktypes.rst
> +++ b/Documentation/locking/locktypes.rst
=E2=80=A6
> +rw_semaphore
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +
> +rw_semaphore is a multiple readers and single writer lock mechanism.
> +
> +On non-PREEMPT_RT kernels the implementation is fair, thus preventing
> +writer starvation.
> +
> +rw_semaphore complies by default with the strict owner semantics, but th=
ere
> +exist special-purpose interfaces that allow non-owner release for reader=
s.
> +These work independent of the kernel configuration.

This reads funny, could be my English. "This works independent =E2=80=A6" m=
aybe?

Sebastian