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Re: [PATCH] rwlock: remove unneeded subtraction
- To: Roger Pau Monne <roger.pau@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Tue, 15 Feb 2022 11:37:45 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 15 Feb 2022 10:37:53 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 15.02.2022 10:39, Roger Pau Monne wrote:
> There's no need to subtract _QR_BIAS from the lock value for storing
> in the local cnts variable in the read lock slow path: the users of
> the value in cnts only care about the writer-related bits and use a
> mask to get the value.
>
> Note that further setting of cnts in rspin_until_writer_unlock already
> do not subtract _QR_BIAS.
>
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
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